Low Temperature Geothermal Power

The ABC recently had a report on plans to power north-west Queensland with low temperature geothermal power using hot water from the Great Artesian Basin.

A Brisbane-based company says it could supply geothermal power to all of north-west Queensland. Clean Energy Australasia wants to build a $50 million geothermal power station near Longreach. But it has now also revealed plans to build a pilot geothermal project near BHP's Cannington mine at McKinlay, south of Cloncurry. The company's Joe Reichman says the Mount Isa region needs about 500 megawatts of power a year and geothermal resources could easily provide that. "It'll change the region into a powerhouse," he said. Mr Reichman says the company has applied for federal and state government grants and has support from the major mining companies in the region. If the projects proceed they would be the first geothermal power plants in Australia.

Low temperature geothermal power is a relatively new (and very low profile) form of extracting energy from geothermal sources that provides yet another option for meeting our energy needs cleanly and sustainably.

Low Temperature Geothermal Power

When geothermal power is mentioned, people usually think of traditional high temperature geothermal power stations using water from volcanic areas, such as those found in Iceland, New Zealand, the US and elsewhere around the ring of fire.

More recently, interest in enhanced / engineered geothermal systems (EGS) - also known as hot dry rock (HDR) or hot fractured rock (HFR) geothermal power - has been high, with a number of experimental projects underway in Australia and Europe.

Low temperature geothermal power is also starting to attract significant interest, as lower temperature water resources are common in many countries (for example, waste hot water produced by oil and gas wells - in Texas alone, more than 12 billon barrels are produced, with oil companies usually re-injecting the waste water into the earth) and new technologies are beginning to appear that allow these resources to be developed commercially.

UTC Power has developed a low-cost Rankine cycle system that can convert temperatures as low as 195 °F (91 °C) into electricity. The technology is similar to a steam engine, with steam or hot water vaporizes a hydrofluorocarbon refrigerant that drives the turbine (it has been compared to a "refrigerator compressor running backwards").

Geothermal Power In The Great Artesian Basin

The Great Artesian Basin provides the only reliable source of water through much of inland Australia. The basin is the largest and deepest artesian basin in the world, covering a total of 1,711,000 square km. It underlies 23% of the continent, including most of Queensland, the south-east corner of the Northern Territory, the north-east part of South Australia, and northern New South Wales. The basin is 3000 metres (10,000 ft) deep in places and is estimated to contain 64,900 cubic kilometres of groundwater.

Most recharge water enters the rock formations from relatively high ground near the eastern edge of the basin (in Queensland and New South Wales) and very gradually flows towards the south and west. Because the sandstones are permeable, water gradually makes its way through the pores between the sand grains, flowing at a rate of one to five metres per year. Discharge water eventually exits through a number of springs and seeps, mostly in the southern part of the basin. It takes up to two million years for water to travel to the springs in the Lake Eyre area.

Temperatures of the artesian groundwater (which is generally of a very good quality) range from 30o to 100o C at the well heads. As the groundwater is too hot for town water supply and for stock to drink, it needs to be cooled down before consumption. That is why cooling towers can be seen throughout the region.

The ABC report's claim that the Longreach plant would be Australia's first geothermal power plant is incorrect.

A small (120 kW) power station (pdf) has been in operation at Birdsville in western Queensland since the early 1990's - one of the few low-temperature geothermal power stations in the world. The plant derives its energy from the near-boiling (98 degrees C) water taken from the Great Artesian Basin (at a depth of 1230m) that provides a water supply for the town. Operation of this geothermal power station reduced the town's diesel consumption by about 160,000 litres per year.

The Victorian town of Portland (in the Otway Basin) also operated a district heating scheme using water from geothermal sources for about 20 years, though this did not generate power.

Geothermal Power In The United States

The UTC plant has been trialled at the Chena Hot Springs in Alaska, with the first plant going online in July 2006. A second unit began operating later that year. Together, the two power units are contributing to the resort owner's goal of making Chena the first totally renewably powered and fueled community in the United States. The Chena experience is motivating other cities in Alaska, including Anchorage to investigate setting up larger scale geothermal plants.

UTC installed more production systems at another location in New Mexico in August this year.

Utah company Raser Technologies is looking to build a range of geothermal power plants throughout the western United States using Rankine cycle systems, with their first plant going live in Utah earlier this month.

Some oil fields also produce hot water which can be used to drive Rankine cycle power plants, with trials being performed in Wyoming.

Geothermal Power In Germany

Germany is interested in deriving significant amounts of energy from both EGS / HFR and low temperature geothermal sources. There are already four small geothermal power plants successfully operating in Germany, albeit supplying only a tiny amount of electricity.

The first geothermal plant to start operating in Germany is situated in Neustadt-Glewe in the north-eastern part of the country. The 230-kW combined electricity and heat power plant started up in 2003 and extracts water with a temperature of 97 °C from a well 2250 meters under the ground. It supplies 1,300 households with heat and a further 500 households with electricity.

Other plants now operating are the 3.5-MW plant at Unterhaching close to Munich, in Bavaria which is the first geothermal plant in Germany to use Kalina cycle technology. At that plant water is extracted at a temperature of 122 °C from a well 3,500 meters deep. Another 2.5-MW plant in Landau taps water of 150°C that is located 3,000 meters beneath the ground. Another 550-kW plant is due to go into operation in Bruchsal shortly, extracting water at temperatures of 128°C from a well 2500 meters deep.

More plants (as big as 8-10 MW) are due to go into operation in 2009-2010 in Sauerlach, Dürrnhaar, Riedstadt, Speyer, Gross Schoenebeck and Mauerstetten. By 2015 there could be more than a hundred plants operating - around 150 geothermal power plant projects are in the pipeline according to the German government. One major constraint on expanding the program has been shortages of drilling equipment.

Geothermal Power In New Zealand

While New Zealand already generates a significant portion of its power using traditional geothermal sources, the country is also conducting a NZ$2.6 million research program into low temperature geothermal power.


Low temperature geothermal power has the advantage of being clean, continuously available energy that can be generated in a wide variety of locations.

Plants will likely to continue to be relatively small-scale, making it a classic distributed energy generation alternative (like biogas and solar PV), with growth probably remaining low profile for some time.

In the long run, I expect we'll see a useful and significant amount of our energy needs being produced using this technology.

Cross posted from Our Clean Energy Future.


I have been posting about distributed geothermal power for a very long time, mostly to yawns and a smattering of denials.

One of the best places to see a successful low-temperature installation is in Husavik, Iceland, of all places. Heat is added to the low temperature geothermal water by a garbage-burning facility. This was also the first implementation of the Kalina cycle in a geothermal power plant. The 3MW plant furnishes all the power needed by a small, isolated village.

Thank you very much.

Thanks for the comment and for the mention of the Husavik plant - I wasn't aware of that one (I assumed all Icelandic geothermal power is the hot type).

More here :


The kalina cycle sure is cool, and 3MW is a nice tidy way to power an out of the way piece of nowhere; But the notion that Geothermal power has anything to offer in terms of energy generation just doesn't hold up to scrutiny; Wind, nuclear, solar all of these are scalable up to the terawatt range. Geothermal... not so much.

TerraWatts would be difficult. But hundreds of GW looks more feasible. Which is still a lot of power. Qualifies as 'significant' in my book. And since it's clean (at least the modern binary plants) and cost effective (Raser has a power purchase agreement for $ 78/MWhe even for a small plant) anything we can get is welcome. If the hydrogen fraction drilling thing works out, a TW might be feasible.

Sorry, I accidently downrated your comment. I had a quick look at the MIT report and it sounds wonderfully encouraging. Thank-you.

What about the rate of heat exhaustion? Will power plants have to relocate to a higher quality site over the heat resource (reserve?) after some decades, centuries, millenia?

Yes. I took a class with Professor Tester, and he explained that the primary issues are flow rate, governed by the permeance of the fractured rock. Where you are mining for heat, you will create a local cool pocket, which will take a long time to regenerate due to natural processes. So, if the area you drill in is made up of very dense non-porous rock, the volume of accessible water around the mine may be limited. He taked about it in terms of a "decades" lifespan for a typical mine, but I would assume that the lifespan would be more than linearly decreased as the power drawn increases.

Thanks for your response. Are there studies comparing the energetic and material costs of construction, maintenance and operation of these power plants with other 'non-polluting' power systems? Any leads?

There was a considerable program on Geothermal in the U.S. back during the last energy crisis. The Hot Dry Rock program got a lot of attention, but there were some significant drawbacks. There were, at the time, lots of reports; I must have dumped at some stage several drawer fulls (Moving offices). Sadly it was before digital records of such things, and the old reports may not be widely available any longer.

mit and google links discuss EGS which stands for Enhanced Geothermal System. Neither article is a refereed technical report. So I cannot determine what makes it 'enhanced' in a technical sense. There is, of course, no existing geothermal energy industry. Only existing geothermal installations. Each installation appears to be uniquely designed for its peculiar location.

Both articles appear to equate 'better' and 'high grade' with higher temperature, so BGs report concerns something out of the box of ordinary thinking. A well known technical problem with geothermal is that the thermal fluid is water. Water is a polar liquid. Hot water has a great capability to desolve naturally occurring minerals, which then flow a short distance in the drill pipe, cool a bit, and deposit out of solution. This clogs the pipe rather quickly. This phenomenon is unknown in petroleum wells, but is a big problem for geothermal wells. Neither article describes or discusses this issue to my satisfaction.

Two short quotations from the mit article:

1) Of particular importance is to demonstrate that EGS technology is scalable and transferable to sites in different geologic settings.

2) The shallow, extra-hot, high-grade deposits in the west should be explored and tested first.

Scalability has not been established. The feasibility of EGS is dependent on local geological conditions. There is no mentioned of how it being enhanced affects its feasibility.

BigGav's new information is about a new idea (new to me, anyway) that deliberately targets low temperature heat. This has the possibility of keeping the wells unplugged longer. It has the down-side that thermodyanmic efficiency is much smaller. But if, in Australia in this artesian basin, they can get EROI that keeps them in business, then good for them.

Sorry - the EGS links were in response to the question of geothermal (in all its manifestations) being able to provide terrawatts of power.

I haven't seen any information on how far low temp geothermal can scale (or at what price points it becomes competitive with other forms of energy).

But the German and Australian experiences and plans show that it could certainly fill a useful niche for providing our future power needs.

Regarding price, Raser gets a $ 78/MWh power purchase agreement. That's just for a small plant (10 MW electrical), perhaps bigger ones will be a tad more cost effective. Even though these systems are modular, large plants should have less overhead costs per MWh.

Do we need centralized power generation ? The power blackout a few years back in Eastern USA/Canada & the Eastern Canadian ice storm demonstrated what happens when the grid is centralized (and improperly maintained). Regional power generation would stop country wide blackouts but would admittedly require more maintenance and not work on economies of scale.

Power also goes down even when the problem is regionalized or localized. To the extent that the individual cannot do without power for any length of time, local backup must be installed.

My worry about Low Temperature geothermal is that the air temperature in Australia is too high to allow much Carnot efficiency. The Iceland project appears to use cold water as the heat sink on the low temperature side. Unless there is a pool of water which is unlikely in Australia I don't know how this will be done.

Currently I am working on the design of the Geodynamics project to be built at Innamincka and there, air will be used to cool the hot steam. This is high temperature steam so the temperature gradient is much larger than for hot water geothermal. Clearly it can and does work in Australia, Birdsville being the proof, but I cant think that air is the best method of cooling but in most of the outback it will be the only method. I know that the output of NZ geothermal stations is air dependent, the cooler the air the more electricity generated.

However in Australia the maximum demand will come at the time of highest temperatures unlike NZ which is the opposite.

Well - it gets pretty cold out there at night and in winter - so its a good match for winter peak demand. But not so good for summer, as you point out.

Even if we don't have optimal conditions, it certainly beats burning diesel for those areas off the grid (whether or not it could compete with solar CSP combined with some form of energy storage is another matter of course).

Mica Creek at Mount Isa currently uses gas for generation although it was coal in the past. There is also talk of a HVDC link from Stanwell to the Isa - Google "IsaLink". Regarding CSP it would complement the Geothermal being talked about. It is just that the efficiency that worries me. Let's say the water is 100C and the air is 0C. That is OK. But is the water is 100C and the air is 50C then that is barely worth bothering with. Of course on a 50C day there would be plenty of CSP.

Mokai geothermal in NZ gets 10MW more generation on its secondary (hot water) cycle at 0C than at +20C ambient air temperature.

The cold side for a geothermal plant can be the wet bulb temperature, which will closer to 0C than to 50C in Australian interior. In any case, the people working this project must have done the thermo calculations and surely have them ready to show to any investor who has the sense to ask for them.

But the cooling towers that they need to get a good bottom temp. may produce local changes in climate, make the desert bloom sort of thing. Still the idea deserves consideration. Maybe Aussies would like to have that desert bloom.

Making the deserts bloom is an age old Australian dream.

I doubt low temp geothermal would make large areas bloom, but it might help create a few oases :-)

Either way, bloom, or not, low temp. geothermal seems a good thing for the Artesian Basin. I'm happy for you having it. Too often a seeming good idea has some killer unintended consequence.

My other halfs father is constantly talking about the old 'plans' to 'turn the rivers inland' and make the desert bloom (how they'll accomplish this in what is little more than sand, I don't know). It'd be an unmitigated disaster for already stressed ecosystems as well (we don't need those Bilbys, do we?).

I like the desert just the way it is.

That's the Bradfield Plan. Turn back the Tulley, Herbert and Burdekin rives (all of which flow into the Coral Sea) to flow into the Thomson River then Coopers Creek which goes in to Lake Eyre. Interestingly it would have passed near where the Geodynamics plant is being built.

The main drawback of the Bradfield scheme is that it requires a lot of tunneling, pumping water uphill (never a good idea for irrigation) and a lot of evaporation losses.

A much better idea was the Reid scheme. It involved taking the rivers that flow into the Gulf of Carpentaria and diverting them over the watershed near to Hughenden. This is better because the water would flow by gravity only and no tunnels would be required. I strongly doubt this scheme would ever be built because it would only irrigate a tiny area of land.

As a final nail in the coffin, the only project that does divert a river inland, the Snowy scheme is currently reversing this diversion to some degree.

Yes but don't you need lots of water for this to spray in the bottom of the cooling tower? There is likely to be very little water around hence the need for air cooling.

If you have an indirect dry cooling system you can take advantage of near wet bulb temperatures for thermodynamic efficiency, while not wasting water up the cooling tower as it's chemically closed loop. The tradeoff is you have to use some mechanical fan power to dump the heat into the atmosphere, but the parasitic load isn't large even in hotter areas, and is mostly compensated by the water saved (in areas where water is scarce, water cooling prices are typically higher). Using a direct dry cooling system (bunch of plumbing with cooling fins and some big fans) has the disadvantage of cooling near ambient temperatures, and still needs mechanical fans to be effective, so typically loses more power than an indirect dry cooling system.

This is not just a concept. There are many GWe of indirect dry cooling systems installed (eg Heller dry cooling systems). They keep getting better too, while conventional wet cooling is not strongly developing anymore, at least not in cost-effectiveness.

No reason you couldn't have a combined solar/geothermal plant. All you need to add would be the collectors.

Moreover, you could add afterburners. For a small fuel price you could raise the steam temp for more efficiency.

Exactly. The gaps and peaks would fill out reasonably with proper system sizing (how much solar thermal capacity for geothermal capacity, ballpark figures, I wonder? Depends on the grid probably). Sharing turbines saves cost. Afterburners are really cheap. Alternatively, water based thermal storage could be added for diurnal storage for the solar thermal part. Unpressurized storage systems for water are low cost and about as simple as it gets.

Since low temperature geothermal has greater site flexibility, there could also be better match with water availability (near large waterbodies) for cooling.

The low efficiency of the power block would hurt the economics of the solar field, although lower temperature collectors are a bit less expensive. They can use unpressurized water just below boiling point as HTF.

TJ, your on exactly the right track. CONFLUENCE.
"No reason you couldn't have a combined solar/geothermal plant."

Or a combined solar/geothermal/wind system. With backup from recaptured methane gas from waste or propane, or methanol from combined carbon recapture and hydrogen produced by renewables. What we have yet to see is the confluence of the emerging technologies, all under control of advanced computer and software control. This is an industry that has a century and more of development in front of it.

The other day, I was looking at a photo of the original Benz patent wagen, the car that birthed the gasoline automobile industry in 1885. A few hours later I had the opportunity to read a review of a Porsche 911 GT2: Zero to 120 miles per hour in 10.9 seconds, it goes faster in it's first 3 seconds of movement than the Benz wagon could ever have dreamed of moving! I wonder if the originators of the first gas powered cars could have ever imagined that such a thing would one day be possible based on their early work? It seems to be physics defying even today.

A twenty year old who lives to a ripe old age will get to see things tomorrow that we today would have thought completely impossible, technical advances that will seem to defy the laws of physics, IF and this is the big IF, if we have the will to begin today. Our generation has seen great wonders. The generation just starting out today can see wonders, if they choose, that will make our technology look like dirty wasteful primitive toys.


Our technology is dirty, wasteful, primitive toys. ;) :(

Wouldn't solar contentrators serve more effectively to super-heat the water? Since peak-demand is usually during the middle of the day, this would match perfectly to the peak power of the sun. Fuel-based afterburners should only be needed at night.

Just a thought....


Hmm, geothermal as pre-heater. That would solve the low temp conversion inefficiency disadvantage. Economics would depend on the cost of drilling the geothermal well versus the cost of the solar collectors.

Don't know about burning natural gas at night though. Competing with lowest cost baseload isn't going to be attractive with expensive natural gas. I'd suggest to only use the natural gas backup during prolonged cloud cover during the day. Some thermal storage could be added to the solar collectors if morning/evening demand is substantial.

It appears there are dozens of variants of these fuel/geothermal/solarthermal hybrids that could make sense. An interesting area for further studies.

Actually (sad to say) gas is used for baseload power generation in Oz now - coal seam gas having become popular for this purpose pretty rapidly in recent years.


Its better than burning coal but far from optimum.

I'm not sure if there is an overlap between GAB geothermal prospects and Queensland coal seam gas fields, but they are certainly not that far away from one another.

A lot of current CSP plants in the middle east are combined gas / solar too, I might add.


Here in the Netherlands there's also a lot of natural gas baseload. Much of space heating needs are also done by natural gas. This is also far from optimal.

The mild climate is particularly suited for affordable air source heat pumps. Geo heatpump systems are more expensive but make sense for bigger buildings, especially when it can be coupled to seasonal energy storage in ground wells. Replacing the natural gas burners in buildings with high efficiency heat pumps saves a lot of natural gas, even if the electricity is 100% generated by natural gas (which it isn't). So this would reduce natural gas demand a lot and provide greater energy portfolio flexibility (electricity is flexible). Important since domestic supplies are dwindling and importing more gas from Russia does not sound like a very enticing prospect to me. Add a mandatory passive solar design on all new builds and we're almost there.

Politicians here are suggesting more natural gas imports from North Africa. This idea belies the conservative energy politics in the Netherlands. Disappointing really. And then they want to build several GWe of new coal fired capacity, propagandizing the 'conventional wisdom' that we really need a lot of fossil fuels, in fact they think it's terribly clever to use a lot more of it. Efficiency scores reasonably well but the policy measures aren't anywhere near agressive enough either. A comprehensive energy saving plan has been made but delayed for years. There is an almost complete lack of vision when it comes to the long term energy portfolio.

Well - it gets pretty cold out there at night and in winter - so its a good match for winter peak demand. But not so good for summer, as you point out.

Perfect for powering lights, solarpanels without storage would actually be worthless for that purpose. Then you turn on the light the f---ing sun is gone.

It's called a battery. You only need a few kWh worth of storage to power a household overnight. This can be achieved with a handful of old-tech lead-acid batteries, or a micro-hyrdo installation, or one of the new-gen 'banded' flywheels, if you wanted to get fancy.

Flywheels will work in a house. No worries about your house suddenly dropping into a pothole at 60MPH. Well, unless you live in California or someplace seismic. Most houses are based in stable areas.

Generally thermal plant gets to temperatures of say 600C or about 900K and the working fluid is cooled to say 40-100C or around 300-350K. This gives a good Carnot efficiency (delta T)/(max abs T) in practice up to 40 or 50% before parasitic losses such as pumping fluids through thin condenser tubes. That puts low temperature thermal behind the eight ball from the start. It's alleged the mixed working fluid (water + ammonia) of the Kalina cycle can beat this limit but results seem mediocre so far.

A point that should be made about Artesian water used on reverse refrigerators like the one at Birdsville is that the water is once-through, not recycled. The need for closed loop or re-used water away from that area is due firstly to lack of top-up water if the upper sandstone layer is dry. Secondly water passing though the radioactive granite below it contains radon which should not be inhaled. Even the air cooled Kogan Ck high temperature coal fired steam station in Queensland is allowed to 'vent off' its radiator water. They also spray water on the condensers from the nearby Proserpine River during heatwaves, not so easy in the desert.

There's plenty more problems with HFR geothermal. I suggest drilling a 4km deep hole in sandstone and granite incurs an energy debt of say 200 megawatt hours. Could be why the Feds helped out with a $50m subsidy. When the granite cools or doesn't fracture properly or the cracks 'heal' due to plastic creep the whole shebang has to be moved sideways. More energy penalties.

I think hfr geothermal is best suited to warming hothouse tomatoes in subpolar regions. I predict only volcanic geothermal will ever produce meaningful amounts of electricity.

Generally thermal plant gets to temperatures of say 600C or about 900K and the working fluid is cooled to say 40-100C or around 300-350K.

What about putting low temperature generation units at the end of conventional steam powered plants to extract additional energy from the waste stream?

I wonder about the general quality of thermal hot water sources. Very often hot water extracts large amount of minerals from rocks including toxic metals in unfavourable locations leading to serious disposal problems. Excessive mineral content in the hot water can also damage generation equipment very quickly too.

What about putting low temperature generation units at the end of conventional steam powered plants to extract additional energy from the waste stream?

You could do that, bleeding off steam from the low pressure part of the main turbine. But it requires increases in the steam outlet regime so loses a bit of electrical efficiency in the main turbine. If the extra electricity generated by the new bottoming cycle is substantially bigger than the losses in the main turbine, it could make sense.

I wonder about the general quality of thermal hot water sources. Very often hot water extracts large amount of minerals from rocks including toxic metals in unfavourable locations leading to serious disposal problems. Excessive mineral content in the hot water can also damage generation equipment very quickly too.

These binary cycles are pretty much closed loop chemically. At the end of the field's useful life, just pump the water back into the well.

I think what they meant was to use something like a freon turbine (or some low boiling temperature working fluid) or the low temperature generation process (<100C) mentioned previously in The Drumbeat. For the former, if cooling temperature is the limiting factor, then little or nothing can be gained by a secondary stage.

There's a difference between condensation temperature and low pressure turbine exhaust temperature. The latter is much higher than it could be because steam turbines are pretty crappy at converting lower temperature steam. The organic working fluids are much better at that, so leaves room for improvement. What you do is you bleed off steam from some lower pressure turbine part and use that to vaporize the organic working fluid for use in the new bottoming cycle. Bunch of valves, pipes and vents basically.

To be really effective, this needs wet cooling at the condenser, but for an existing plant retrofit it actually saves a bit on cooling water due to increased overall electrical efficiency. However, an indirect dry cooling system would work well enough too and doesn't use up cooling water.

Not sure I follow, but what I was suggesting is using the condenser from a typical steam turbine as the boiler for an organic working fluid turbine, similar to this approach.

Well I suppose you could do that too. The thing with steam is, in order to have decent pressure for mechanical energy conversion, you need to have high temperatures. After all, water only starts boiling @ 100 degrees C and pressure only builds up relatively slowly with temperature rise beyond that point. So basically the lower temperatures are pretty crappy for generating motion (and subsequent electricity via generators); the high and intermediate pressure stages is where most of your power comes from. So if you're going for the freon bottoming cycle anyway, you might as well go up a few stages back into the turbine and bleed the steam off from there, to get more power from the total plant, since the freon (or other ORC - no not those green creatures!) is more efficient at these temperatures. For a new powerplant, this will make even more sense as you could ditch some low pressure sections in the steam cycle, so as to save equipment and probably cost.

There may also be practical problems with maintaining a near vacuum in the condenser if you want to adequately transfer heat to the organic fluid while still cooling effectively. If you bleed off the steam from a few sections up in the turbine, you get a bit higher pressure which is helpful.

I'm not sure why you would want to use brine. The lower freezing point isn't really necessary but there is some advantage in thermal properties for heat transfer. Not really a huge advantage, and if not designed properly, the salt will give you trouble. I like ORC bottoming cycles because:

- they're simpler than steam cycles (there is no condensation of the organic working fluid on expansion in the turbine)
- they can substantially improve overall thermal powerplant efficiency (favorable vapor pressure and low heat of vaporization, unlike water which has an absurdly high heat of vaporization that hurts system exergy).
- we can build a lot of retrofits to existing powerplants quickly and cost-effectively (only add another turbine).

Perhaps the gov't can help with a fund to pay for unproductive drillings to reduce the risk of drilling (resulting in more drilling for geothermal heat fields). They have something like that here in the Netherlands although it's for low temperature low depth fields for space heating coupled to heat pumps.

A Carnot ideal efficiency operating between 100 deg C
and 20 degree sink has a low efficiency=1-(293/373)= 21%, but practically it is probably closer to 12% efficency at best.

Here's an 8.6% efficient organic rankine cycle plant in Chena, Alaska(150 degree F hot springs water) produces 210 KW of power with a 530 gpm 'boiler' pump and a 1614 gpm 'cooling tower' pump. That's a lot of water!
The project was judged successful because it displaced the fuel for a cheap diesel power plant.


Excellent article, Gav. Not only does Australia have substantial geothermal power potential, but so does North America and Europe, for starters. This is a vast untapped resource that could be the replacement for coal-burning power plants (and gas power plants in the EU).

Thanks Will - nice maps.

It looks like Turkey should be considering pumping geothermal power into the European grid - it might help wean people off Russian gas imports somewhat.

Turkey does look like a real sweet spot, also because it's adjacent to the ocean which provides a stable and cheap heat sink (air cooling would lose a lot of power for a relatively low temp heat source in warm Turkey). Cheap labor for installation and operations too (a benefit when exporting to countries with higher wages).

Maybe this will prove a bargaining chip for Turkey to join the EU?

Offshore geothermal looks huge on the westcoast of the US and Mexico. Ocean floor is relatively thin, drilling through water is easier than granite.

Geothermal drilling rigs, better than oil rigs.

Cost would be quite high though I'd imagine.

I understand why the Applacians are a cold zone (dead faultline), but I would have expected a lot more heat at the boundry between the north and south american plates...
Lot of heat in the Pacific basin as well.

I think enhanced geothermal is the most underestimated of all energy technologies. Maybe this is because all is hidden below the ground and as the industry is still in its infancy.

But as soon as this has become cost competitive the resource potential is huge. This technology is no more restricted to the wold's hottest spots it can be applied in large parts of the planet. For example a 2007 MIT report suggests that 100,000 megawatts (MW) of electrical generation capacity could be met through EGS by 2050 with a modest investment in Research & Development (R&D).

Another study showed that it could supply half of Germany's electricity demand.

The special issue is that enhanced geothermal has many simlarities to advanced oil techology (drilling, fracking, resource engineering...). So it is possible that as soon as the oil fever has cooled down these will be the new hot jobs for petroleum engineers.
However at present this is also one of the handicaps of geothermal, as both are competing for drilling rigs, personnel et cetera.

Seeing as how MIT have promised that geothermal is a goer I presume it will now get the same big bucks as carbon capture and storage. After moon shots and cancer cures the mysterious underground must be our last remaining frontier. The Mayans threw people down the well at Yucatan to appease the gods. It seems we're about to throw many millions at geothermal and CCS in the hope the underground gods will smile on us.

...maybe eventually cynics like you will be thrown down as well...

Maybe the Mayans did rain dances to help the crops grow. The cynics built dams.

According to the Geothermal Energy Association (2007)


Enhanced Geothermal Systems currently generate 0.37% of the electric power in the U.S. New projects in 12 states will double this amount to total nearly 6,000 Megawatts of power in several years.

A 2007 study by MIT, "The Future of Geothermal Energy,"


concludes that by 2050 the U.S. could increase this amount by 100,000 MW, thus generating about 10% of the nation’s electric power.

Hence, EGS power will not make significant reductions in the use of oil and natural gas in producing electric power for at least several decades.

As oil production declines in the coming years, the highways will fail due to a lack of maintenance (high oil costs/gas stations closed and).

Then, the electric power grid will fail due to a lack of maintenance. The highways carry maintenance trucks/crews for repairs/replacements, enormous transformers, high tension cable, and pylons.

There are no indications that power companies are buying trucks that will run on electric power, and even if they had such equipment, it won't be able to function when the highways collapse.

There are no indications that state governments are buying trucks that will run on electric power (for highway maintenance), and they don't have funds to make such major purchases. Even if they did, electric powered trucks have a very short range: 100 kilometers without hills.

The time for this collapse is approaching rapidly.

Time to plan for Peak Oil impacts.

The only thing that I want to see collapsed is your Ph.D.

Hi cj. I've been in the transportation industry, both air and ground, for over 30 years. Like you, I'm concerned about our transportation infrastructure. I agree alternatives to liquid fuels are going to be too little and too late in the short term without major changes. However, alternatives to liquid fuels will be the solution in the long term, perhaps starting around the mid 2020s. The question we desperately need to answer is how do we keep our transportation infrastructure from failing during the short-term transition period (the next 15 years)?

There is only one way; a huge amount of demand destruction. I like to think of demand destruction in three parts; voluntary, involuntary, and technology.

1. Voluntary demand destruction is conservation.

2. Involuntary demand destruction is forced reductions in liquid fuel use.

3. Technology destruction is improved efficiency in vehicles using liquid fuels.

I believe the data will show we can squeak by. It won't be pretty, but we should be able to prevent a downward reinforcing cycle that cripples our transportation network to the point where the far reaching consequences are unthinkable. For now, I'm just setting the stage for future discussions which will include data to support my belief.

Hi Priority X,

No one has any open pond or ocean grown algal biodiesel out of the R & D phase, so there are no liquids on the horizon that will fill the gap.

The Energy Watch Group (funded by the German Parliament) concludes in a current report titled: “Peak Oil Could Trigger Meltdown of Society:”

"By 2020, and even more by 2030, global oil supply will be dramatically lower. This will create a supply gap which can hardly be closed by growing contributions from other fossil, nuclear or alternative energy sources in this time frame."


Cliff Wirth


BioProcess Algae expects to produce algae at Green Plains' ethanol plant in Shenandoah, Iowa, sustained by the plant's recycled heat, water and carbon dioxide.

200 (at present) plants producing heat, water, and carbon dioxide. Makes sense to me. If it's gonna work anywhere, this seems like the place.

Cliff announces that soon he will produce enough energy from old bubble gum to avert any Peak Oil crisis. All is well.

The world is saved! Ronald Reagan was right, not to worry.

Not disagreeing with this report. There will be a gap. But it's a long sight from a "gap" to a total collapse. We could cut our demand in half literally in a year and still keep our current society relatively intact. This is actually very likely to happen (but not in a single year).

What would it look like? Probably something like this:

1. No new construction-- or very little, only the most essential
2. Carpooling (not hard to cut commuting miles in half, or more)
3. Lots of demand destruction for wasteful consumption of goods and energy
4. Prioritization of energy for the essentials: food, water, basic maintenance
5. Increased efficiency emphasized across the board

There is enough time, if measures like this are taken (willingly or by force of the market), to build up a suitable renewable energy infrastructure. Nothing that will provide us with the excessive lifestyles of today, but enough to provide our needs.

Is this going to be an easy transition? Hell no, but is it impossible? No.

I've asked several times, but don't seem to be able to get concrete answers.

1. Why is it so inevitable that the highway system (along with practically everything else) will totally collapse? What good reasons are there for the Olduvai Last Blackout theory, other than it just sounds logical to a mind already reeling from the thoughts of the (real) effects of Peak Oil? Peak Oil provides a reason for plenty of problems in the short- to medium-term, but nothing that will necessarily cause a collapse. Humans can and do cause royal foul-ups, and that is the biggest risk here, not some fundamental drop off some imaginary energy cliff, which cannot be avoided no matter what we do.

2. How rapidly is this total collapse approaching? I keep hearing it's "near", "approaching rapidly", etc. Any idea of time frame, even an order of magnitude estimate? 1 year? 5 years? 10? 20? 30?

"I've asked several times, but don't seem to be able to get concrete answers."

1. If you get a concrete answer to your collapse question depends on what you consider "concrete" and what you consider Collapse:
I think the main issue of any "collapse" question is that there is no Yes/No answer to it - which might be what you consider concrete. Unless you are thinking of an Apocalypse in religious terms (which cannot be resolved scientifically) in complex systems like e.g. world economy there is no such thing like a sudden switch from "everything fine" to "total doom" but myriads of situations that are "worse" or "better" than others. So for example the the collapse of the Soviet Union meant several pretty hard years for the Russians, but this was still nothing compared to the recent history of places like Iraq or Afghanistan.

2. The peak of global oil production may be a major tipping point. Of course nobody can *know* when this will happen (or has happened). Some say oil has already happened (e.g. in July 2008), others like the IEA stick to the infinite improbability that OPEC will be keen to keep oil cheap as long as possible, pushing peak oil back to after 2030. And there are still a few industrials left that assure that due to the market's invisible hand and the incredible speed technical progress there will never be a peak of anything.
Apart from the oil peak other tipping points are probable, e.g. peak phosphorous or water shortages due to climate change.
All this can have a serious effect on the world population and their life quality. For example before the "oil age" a hundred years ago earth was inhabited by only 1,7 billion people. And before artificial fertilizers (phosphorous!) was introduced one century earlier this planet only supported 1,3 billion humans.
So if you ask me if a collapse to such levels is possible my simple reply is: yes. My more complex answer is: this may be more complex:

3. A decline in human life quality and quantity doesn't necessary mean a collapse must be forever. I can well imagine that at least as soon as policymakers and consumers realize that there IS a supply issue they will speed up to develop more sustainable fossil-free solutions like renewables, recycling and efficiency.
Of course with this will be hard under the conditions of the economical downward spiral - just like the situation the oil industry is facing now. I think that there will still be humans on this planet after the fossil age and that eventually they'll have found ways to lead a good and healthy life.
But the decades until this is achieved can be pretty tough.

100GW of geothermal capacity in 40 years is 2.5GW additional capacity per year. This is enough additional electricity to power 5million new electric vehicles(one third of new vehicle sales in US). Another one third can be powered by todays additions of wind capacity(7.5GW/year). Not sure how the other third will be powered but society is not going to collapse if only 10million new vehicles are sold per year.

"Then, the electric power grid will fail due to a lack of maintenance."

I have asked you before to give an estimate of oil used by electric grid maintenance. Is it 2,000 boe, 20,000 boe per day?? In 30 years state governments will have to replace most of today's vehicles, they will replace with ICE using diesel if oil is still available or CNG or biodiesel or electric depending upon whats available in 2040.

"The time for this collapse is approaching rapidly".

Give us your best estimate and how much oil will be available the year of collapse and why this will not be enough to keep police, fire, medical, electricity rail and other infrastructure in working order?

It takes energy to get energy, and energy is getting more expensive.

Gasoline and diesel may be cheap today, but most know that oil prices will rise again, and so too will the cost of producing/extracting any other energy.

Oil is the great enabler of all other energies.

As the price of oil/future oil increases, it costs more and more to produce/extract any energy; thus energy companies, investors, and bankers look askance at projects that may not be profitable.

The energy inputs are more than most think. There is the energy used directly in extracting, processing, refining, and transporting, plus all of the salaries of all employees which are spent and use oil, natural gas, and coal, plus part of the salaries of the employees that supply services and parts (it's a lot) which are spent and use oil, natural gas, and coal, plus all of the oil used in transporting all of the employees and the parts and equipment. All of this energy is necessary to get some energy into an automobile gasoline tank, for example.

We are beginning to see the limits of "Complete EROEI," or C-EROEI. This is why the collapse will come sooner than many think.

Meanwhile, back at the ranch. Because profits are not certain, private investors will balk, and there will be some delays with energy production/extraction.

This will be followed by great public clamor for "more, more, more --- energy, and more of the good life, and "drill, drill, drill," and such stuff..

The government will respond with programs/subsidies. This will continue even after the C-EROEI is less than one.

The government will subsidize solar/wind, even though investors know we will have spare electric power as the gourmet coffee stores, plazas, factories, big box stores, and offices close.

Our dreams and illusions have real limits.

Here come "the saw teeth," from TOD folks, "The 2008 IEA WEO - Oil Reserves and Resources," November 22, 2008:

Davebygolly: given the retreats in energy investmenst seen recently, I would think that a lot more of the remaining reserves will remain forever in the ground than was thought - the 2500 gb isn't real in that sense. The energy industry is highly capital intensive. I don't know how many blows like the current one it can withstand. So maybe there will be a few more reruns of the present crisis on the downslope, but maybe very few and not so far in between.

Like everyone else, just guessing. But we know where we are and we know where we'll end up. Just don't know the shape of the downslope. Linear? Naw. Vertical drop? Naw. Exponential dacay? Naw. Sawtooth down? Has to be, of one sort another, having excluded all else. How many teeth? A lot is not that much different from linear. Not so many and then a downward plunge as the world's infrastructure no longer can support the energy industry's ability to get ever arder to get at stuff.

Rockman: "I agree Dave. I've worked in the oil patch for 33 years and have lived on that saw tooth ride everyday of it. In the past, the aberrations we're caused by excessive production, economic down turns and growth spurts and a combination of these components. It seems we are now entering a period were those factors are still effective but have now added a new dynamic: inability to supply demand (at sustainable prices) during periods of growth in the global economy. I think it's becoming apparent that even as we slide down the PO slope we'll still experience the saw teeth. And those teeth will exact even more damage to mankind's ability to sustain itself in an orderly fashion."

Cjwirth: "Hey Rockman and Dave,

I like your saw tooth theory. The big saw tooth comes when the high price or lack of oil reduces the ability of states to maintain the highways.

[Google: state highway government budget cuts]

Then the power grid goes out and nothing modern works, including heating systems and transportation (electricity power pumps diesel and gasoline).

This will reduce the population of many cities, which provide the organization and finance for extracting and distributing energy. There could be smaller of such saw teeth when there are power grid failures in sections of the U.S. for weeks or months, or for a short duration nationally.

Another saw tooth is when gas stations are closed and people can't get to work to do the jobs required for oil or gas extraction.

When your car runs out of gasoline it stops. When the industrial machine doesn't get enough oil, something stops, and then that stops something else, I call this the 'gridlock effect.' " [credit here to Chris Shaw: http://www.onlineopinion.com.au/view.asp?article=5964 ]

Aangel: "One more sawtooth: when the cost of transportation gets so high that it is no longer worth it for a minimum wage worker to go to work."

Humpty Dumpty sat on a wall.
Humpty Dumpty had a great fall.
All the king's horses and all the king's men
Couldn't put Humpty together again.

Peak Oil is here now >>> Four years on a plateau of crude oil production, despite very high oil prices and increasing demand.

Cliff Wirth

We are beginning to see the limits of "Complete EROEI," or C-EROEI. This is why the collapse will come sooner than many think.

Your 'C-EROEI' is still EROEI, you just purport to dig a little deeper than others. If we take this to the (il)logical extreme, we have to go all the way back to the Big Bang, conclude everything is pointless, and top ourselves now to get it out of the way.

Hi Bellistner,

Yes I invented the C-EROEI stuff as some were not looking at all required energy inputs to get gasoline to your car or wind turbines delivering electricity etc.

No you don't have to go back to the Big Bang, only to that human activity that uses energy related to that use of energy that is necessary to produce/extract energy. So, if someone drives to work at a parts factory that makes equipment for a drilling rig, a portion of that gasoline for transportation must be counted. I say a portion, because the parts factory makes unrelated parts. They must be paid to work and they use oil when spending the pay, so that gets counted. Because there are so many confounded energy input variables, it is not possible to measure them. But this is what goes into decisions about whether drilling for oil is profitable.

In the future, governments will provide more and more subsidies to drill for oil, and will do so after the C-EROEI is less than one.

Thus we will be drilling ourselves faster and faster into depletion. Thus "drill, drill, drill" will equal "deplete, deplete, deplete."


Cliff Wirth

I have challenged you a few times; " how much oil is required to maintain the US electricity grid".
Not how much energy is required, not how much oil, power network employee's girlfriends or children use NOW, not how much tar is needed to repair ALL the roads in US, HOW MUCH OIL is needed to directly maintain just the electricity grid including roads to access 4 WD vehicles!
I will help by giving my estimate; less than 20,000 barrels/day(<0.1%).

Now tell me why this amount of oil will not be available in next 20, 30 years?

Hi Neil,

When the gas stations are closed and people can't get to work, that's it, there goes highway maintenance and the power grid. When state governments don't have revenues to put highway crews out in trucks that use gasoline and diesel, that's it, etc. etc.

4 wheel vehicles need open gas stations with gasoline/diesel to get out there. 4 wheel vehicles do not carry huge transformers, pylons, or cable all from hundreds or thousands of miles away. The transformers, for example come from Germany or South Korea.

No one is going to plan ahead as you are to figure out how to overcome these problems.

Governments are totally ignorant of what is happening and they are not planning.

I have personally been in communication with a colleague from grad school who works for a state FEMA agency. He ignores everything about Peak Oil.

I taught government officials for 30 years in 3 MPA programs until January 2008 where I retired from the Univ of NH, and I have many friends in government who I communicate with regularly. Government is my life. Most do not want to hear about Peak Oil, and most run from it like it is the plague.

Will the National Guard come to the rescue. Yes, when it is too late, and they too need gasoline stations open in order to function.


Cliff Wirth

Yes, infrastructure is a problem - and the thing we are mostly running out of is time.
So maybe for remote locations that will risk to get "cut off" from the grid it may be worthwhile to consider an "energy island" approach: village electrification systems like in rural places in China or India. In those places now often photovoltaics is used to provide electicity for basic needs, as it is cheaper and more reliable than for example diesel generators.

The highways carry maintenance trucks/crews for repairs/replacements, enormous transformers, high tension cable, and pylons.

I hardly think the current highway system is a prerequisite to transport heavy items. We did it for years with railways, and the Russians have some very nice (robust!) off-road Heavy Vehicles that can be used for the 'last mile'. :) UNIMOGs look like they have potential as well.

In more good news that could be applied to this tech:

Electricity from Waste Heat

Factories, data centers, power plants--even your clothes dryer--throw off waste heat that could be a useful source of energy. But most existing heat-harvesting technologies are efficient only at temperatures above 150 °C, and much waste heat just isn't that hot. Now Ener-G-Rotors, based in Schenectady, NY, is developing technology that can use heat between 65 and 150 °C.

It's been done already. Power output is minimal, though.

Low temp heat engine

Geothermal maps for the Western US

A question for some of you geothermal experts out there:

With regard to low-temperature geothermal, is there any rule-of-thumb that is commonly used to correlate a unit amount of power produced (let us say gross power inlet to a heat engine, not net electrical power produced) to i) the amount of required surface area of subsurface piping, and ii) overall temperature differential between heat source and sink?

What I have in mind is some range of values in terms of say the amount of pipe surface area required per megawatt of gross power delivered to the surface for a given temperature differential.

I would imagine that a low-temperature geothermal systems starts out with a very high rate of heat transfer when first installed, but then settles back down to some lower steady-state level after a temperature gradient becomes established between the subsurface piping system the surrounding ground. It is that rate of heat transfer that I would like to get a handle on.

Dry rock has very poor thermal conductivity. Collecting heat by having a pipe containing a heat collector fluid penetrating a mass of dry rock is an absolute non-starter. To gather heat, the fluid must leave the pipe and flow through the rock, and then be collected again in another pipe. For this to happen, the rock must be porous, or, perhaps hydro-fractured. The heat collection effectiveness depends critically on how porous. And on whether the rock is soluable in the fluid. The economics depend critically on the fluid being cheap so that one doesn't need 100% recovery to make a profit (don't think of circulating hydrocarbons (oil) to collect the heat).

None of this has actually been done in enough different places to have any engineering experience on which to base rules of thumb.

geek7 -

Thanks for your comments.

So, in actuality it sounds like the most workable scheme would involve a grid of injection wells and a similar grid of recovery wells, the fluid (no doubt water?) flowing from the injection well, through some distance of a porous formation during which time it becomes heated, and then back up the recovery wells and thence to the heat engine. Close?

If such is the case, I can see why it might not be all that easy to apply any general rules-of-thumb regarding typical heat transfer rates. I can also envision potential problems with mineral precipitation eventually plugging up the pores of the formation.

If you have porous/brittle sediments, you can force water down under very high pressures to create and artificial well. That's the main idea behind EGS isn't it? There are various other problems. For example, the artificial water well has to be large enough to have enough orb surface area for heat transfer, but not too large as that may decrease the temperature in the well too much. Since there's little experience with this, learning must be done the hard way by trial and error.

One of the hassles which has happened in Europe will be unlikely to cause problems in most of the sites in Australia due to the low population in the relevant areas - subsidence and earthquakes.
One of the biggest other issues is that it is difficult to predict how well the rock will fracture, which lead to one of the sites only working at half power as one of the bores to pump in water did not do anything - I do not know if they subsequently overcame this.
Regardless of this, geothermal is a genuinely hopeful source of power, and in the Australian context where high daytime temperatures often reduce thermal efficiency should perhaps best be regarded as an alternative to back-up storage for solar energy, since the efficiency of the geothermal plants would be greatest in the cool of the night, just when solar power is not available.

Considerations of water supply perhaps present the most severe constraints on siting in the Australian context.

Water supply = Great Artesian Basin.

EGS in Australia is supposed to be closed loop in any case - net water consumption is expected to be low.

Indeed. That is why I mentioned it as a constraint to siting. This is some distance from many of the main population centres, and so power would have to be transported some distance for really major use.
Not that I consider this to be show-stopper - it is just that the location is constrained by this, just as it is in Europe by the positioning of fault zones and cities.

One of the most important elements of solving our energy problems is an expanded, smarter grid.

Australia can go 100% renewable by building a few HDVC links and tapping just a small portion of our immense solar, geothermal, wind, wave and tidal power resources (no doubt supplemented by coal seam gas for a few decades).

Geothermal (and solar) in central australia is right on the key routes - thus the locations are good.

How does that best get communicated to the Rudd Administration?

Well - first you have to remove the influence of the coal industry - at the moment we have people in government pretending large scale 'clean coal" is the solution (and coal seam gas - which is real - rapidly making inroads into east coast power generation).

There is an energy white paper being prepared right now I think, so presumably here is (or was) a submissions process - we may even have blogged about it at TOD ANZ, but there have been so many government enquiries into energy and climate over the last 2 years I've lost track.

This may be achievable, - Australia running on renewables- and certainly Australia is in a very favourable position to do so relative to other countries.
However, the extent of the readiness of renewables to do the job right now at reasonable cost is not yet entirely clear.

Geothermal looks very hopeful, but this is in no way the same as saying that more advanced systems than those use in traditional situations are fully ready to roll out at large scale.
In particular hot dry rock resources may be more expensive or less practical than is presently envisaged, as the fractioning of rocks does not seem to be entirely predictable.

I would like to make clear that the chances of it working out fine seem good to me, as likewise do the chances of solar PV and thermal being widely available at a reasonable cost. However, we still do not know this for sure, and measures we do know how to do are the ones to really push, with vigorous research and pilot plants in the other fields to clear up the remaining uncertainties.
For instance, to take a small example residential solar thermal can make a massive contribution to Australian energy requirements but is still not being rolled out at very large scale, I understand.

In the context of solar thermal, Cyril R has answered my questions regarding the cost of dry cooling:

It is very pleasing that the costs seem reasonable, and so the many favourable locations in Australia for this sort of energy can be utilised without unduly stressing water resources.

By residential solar thermal do you mean solar hot water heaters ?

I'm not sure how much market penetration they have, though when I grew up in Perth (a couple of decades ago) they were pretty common.

There has been plenty of incentives given to these in recent years, but they seem rare in inner Sydney - not sure how prevalent they are in the western suburbs.

Its certainly something we should hopefully see on every rooftop in the longer run - one of the quickest and most effective ways of cleaning up the energy supply.

Solar hot water heaters are practical even in the UK, and operate at a high efficiency since you are not altering the state of the energy.
If Aus is anything like the UK though, the costs are probably still high, with large profits being taken at every stage.
Even in winter at latitudes at a distance from the equator they can contribute, and for areas with a lot of sun should do most of the job of water heating.

Huge amounts of energy can also be saved in other ways by proper design adjusted to the climate.

One area that I would be very interested in were I based in Australia would be air source heat pumps - they are wonderful for heating, I have not researched how they do for cooling.

There is also potential to use refrigeration units as heat stores to compensate for the variability of wind:


My approach tends to be very practical, based upon what can be done right now with current engineering, and it is clear that considerable advances could be made without going outside of the envelope of what is established engineering.

Greenroof technology and the use of greywater could transform Australia's impact without needing any new technology at all.

If you're in the UK it will probably make more sense to install one of those ecocute heat pump water heaters. Ideally, you'd have a passivhaus as you've talked about before, and use the ecocute unit on the colder days, for high efficiency space heating. Now airconditioning is something you'd rarely need in England but running the heat pump in reverse can do that too. High efficiency heat pumps feeding into integrated floor and wall heating systems are really the best for new builds, but unfortunately very costly for existing buildings.

I think it was Pitt who pointed out that the delta of putting in a heat pump in a very energy efficient house make it not worthwhile.
I've got similar reservations about the plans for British zero carbon homes, as they tend to rely on very inefficient and dinky local wind turbines, solar PV which are insane in the British climate where you have a grid connection and so on.
Any criticisms I have made about the economics of off-shore wind pale against the cost per Kwh of this sort of measure.
Someone, Windspire, has actually carried out some impartial measurements of the energy generated:

As can be seen in the graphs given, at about $5,000 for 1.2 kw installed, most areas will be lucky to get 500kwh or so of energy a year, at the height these things are.

If I were off-grid then it might make sense, and I would trust these guys more than most of their competitors, as the presentation is fair, and at least the damn thing isn't installed on the roof to possibly cause structural damage and isn't noisy.

By the time you have installed batteries etc though unless you live in a very windy area indeed the cost doesn't bear thinking about.

In present financial circumstances, getting the job done roughly seems the way to go, rather than spending a fortune on gold-plated perfect solutions, so you just try to improve things as much as you can as cheaply as you can.

I am a believer in KISS - the UK Government has allocated £100 million to insulation, which will do 60,000 houses at a cost of around £1,666 each.

In the UK there are 3 million houses in the lowest insulation band, with almost no insulation, and 9 million in the band just above, out of a total housing stock of 24 million.

The money that is being dished out on a VAT reduction etc, around £20 bn, could have paid to insulate all those houses to a basic standard, and would have employed a lot of out of work builders.

We have made such a cock of securing energy supply that it seems to me that our best bet may be to go for 'virtual watts', as we simply don't have the time to build the needed plants.

Air source heat pumps can be mass produced, so you would basically build two, and install one in a French home and one in a British home - the French have an installation program which aims to install 50,000 a year, from memory, and the efficiency ranges from 2.5 in an existing building to 4 for a new build.

You would also need more transmission for the power, but it would provide very low carbon power very speedily simply by using the existing French nuclear build more efficiently.

The installation needed would also employ some of the laid off workers.

Most heating in the UK is done by very efficient combi boilers, and given the present relative costs of gas and electric most would not save anything - except I doubt that the gas will remain available, and if it does will be at a higher price.

Around 60% of household energy bills are spent on heating water and space heating, but I am not clever enough to work out what the cost per kilowatt would be to buy and install two or more air pumps as an alternative to building more power plants.

Anyway, it is a thought, albeit a somewhat desperate one.

I think we are going to freeze.

Good points, although I wasn't talking about zero carbon houses with wind turbines, just buildings with very tiny space heating requirements due to passive solar construction. Really simple contraptions like solar walls are very cost effective even in colder climates (from the builtitsolar website). Of course good insulation helps a lot too and is often very cost effective.

Does Pitt realise that there would still be hot water needs in a passivhaus? That's where the synergy is. You could use the same heat pump system for heating up your shower/bath/washing water for some extra space heating when it gets colder/cloudier for the passive solar design to work. Or run it in reverse as airconditioning when the ambient temperature gets too high. The system would only have to be slightly oversized due to the excellent insulation performance of the passivhaus (low heat load). I've linked to PDFs before that show this is cost effective for a low space heating requirements.

I really like your virtual capacity concept. Should be really easy in Europe with the reasonably interlinked national grids and markets.

Hi Cyril.
I believe some designs along the lines of Passivhaus use solar thermal water heating.
I was really commenting on British ZED plans, which specify that the house, or at least a small locality, should be entirely carbon neutral, and hence need relatively expensive micro-generation

Solar PV arrays on the grid in any case rely on the grid for power in the winter at British latitudes, and so the cost effectiveness is even worse.

A heat pump for a block of houses might work in a cost effective way with very energy efficient houses, used for the hot water - in a lot of regions of Europe the hot water is plumbed in from CHP units etc.

Cyril, I wonder if you could or would fadge up some rough figures on the costings per kw or kwh of virtual generation by the installation of heat pumps where the electricity source is nuclear?
It is well beyond me - I would be bound to loose several decimal places - they are tricky little devils, and slip out of my pockets!

There is actually a 2GW line installed from France at the moment, and the energy could be used more efficiently, but the complication is that the electricity would not usually be used for space heating in the UK as gas is usually used for that.

The key to Britain's energy future is the European supergrid proposal.

Once you've got large scale north sea wind power and north african solar feeding the continent, the problem will be largely solved.


I feel that you are overstating your case.

I consistently support solar power, and it is clear that in hot areas where peak demand occurs in the daytime, or near to it, that a very large contribution to power needs can be expected from solar.

At the end of the day though, we only know what we can do and at what cost after experience is gained, and the actual state of play at the moment for anything like that which you suggest is very far from being an engineering reality.

To summarise the difficulties which you are saying we will be able to overcome, you are sacrificing most of the things which are bringing solar power to cost comparability, and even at it's best it is nowhere near that yet.

You are shipping the power from North Africa to Europe, which has maximum demand in the winter, and the solar resource even in the parts of North Africa which are reasonably proximate to Europe are far less than in the summer.
Here are the figures for Cairo, which at 30 degrees north is at a comparable latitude to most of the areas in question:
See figure 1.6

It is clear from this that both the shorter hours of daylight and the reduced power of the sun significantly affect the power available.
Of course this can be moderated to a degree by strategies in placement and alignment - thanks Cyril, for information on this - but just the same the basic problem remains that you are getting the least power when you need it most.

You also have the not insignificant obstacle of building a transmission infrastructure.

Here is the actual state of play on building a thermal solar power array and shipping the power to Europe:

The plant will be a hybrid, using both sun and natural gas to generate 150 megawatts. Of that, 25 megawatts will come from giant parabolic mirrors stretching over nearly 2 million square feet -- roughly 45 football fields.


As can be seen, this is basically a gas burning plant topped up by a little solar power.
It should also be noted that this is a relatively inefficient use of the gas, as in the UK if it were shipped directly here instead of being burnt in situ it would be used in the very efficient gas boilers.

They are not burning the gas for arbitrary reasons, but because storage of solar thermal energy is still in it's infancy, and to use the power equipment efficiently you need to keep it running to amortise the cost, and as stated previously the contribution of solar also decreases in the winter.

Can we do better in the future? Sure thing, but none of us know just how much better, and it is simply far, far too early to come out with statements such as that solar power from North Africa will be powering Europe.

Similar difficulties apply to wind power from the North Sea.

All these things always work out on the basis of cost, and even if one ignores nuclear power it might be that the cheapest way will be to use ocean currents, or whatever.

The technology is too immature to pronounce it a winner.

The prospects for both wind and solar power are far better in Australia.

I'm in favor of a substantial nuclear buildout for countries that already have nuclear power (at least doubling of current capacity - france can act as virtual capacity hub). But I don't think the annual variation will be a serious impediment for solar. There's not a lot of annual variation in plant output in places like Tamanrasset. They're even better in this regard than most US soutwest locations. And why would the annual aggregated grid load curve be much different for a combined European grid than for a combined USA grid as hypothesised the Ausra PFDs? It appears to me that the effective load carrying capacity over the year is better than baseload nuclear so there's solar has no weakness there.

In general, most of the predictions I've seen regarding solar cost do appear very plausible, but perhaps a bit too optimistic on the timeline at which they can achieve it. This doesn't make all solar techs winners but it's highly likely that several of them will be very cheap in the future; before we run into the more serious intermittency issues, there will be many more iterations on the learning curve.

We don't really have a lot of options. Dirty coal is unacceptable and all that cleanish coal with CO2 abatement (CCS or olivine sequestration) has proven is to be not cheap at all. The clean coal optimism is basically at odds with the solar optimism. It's a moot argument. Future nuclear cost aren't clear at all. We just have to live with greater uncertainty than ever in power markets. One of the biggest challenges, then, is devising a flexible policy framework with good dynamic cost effectiveness. Grand plans don't fit into that easily, but some things, like a substantial cost (tax) on fossil carbon, and agressively pursuing conservation and efficiency, are no regrets and should begin immediately. It pains me that the EU is stalling more agressive energy policy, for no good reason. Credit crunch? All the more reason to stimulate the structural economy like energy equipment and infrastructure. Waiting for the next US administration next year? Not necessary. Waiting for China? Bad idea.

They haven't built an integrated grid in the US either yet.
My point is not that substantial future progress may not be made in solar power, but that at the moment we are struggling to get it competitive in the most favourable circumstances, and it is far to early to say confidently that it can power all of Europe, or the US for that matter.
The 'Grand Plan' outlined in the 'Scientific American' in fact relied on massive burn of natural gas when you dig through it.
I therefore outlined some of the substantial remaining obstacles to doing things that way.
It is not clear if they can be overcome at any affordable cost.

I'm happy to use as much solar power as is available as it becomes competitive.
However firm plans should in my view be based on what we currently know how to do, mixed with support for developing new resources.

Yeah, afraid the US grids are strongly balkanized. Europe has better perspective for stronger integration of national grids on the short term. However, US grids tend to be antique and need major refurbishment anyway. Extending and aggregating grids is probably a good idea anyway.

I've got some reservations about relying to heavily on nuclear fission as well. Costs aren't proven for gen3+ reactors, one could easily argue that they are also struggling to get competitive. Whether this is a first of kind plant cost we don't know; historic learning curves suggest nuclear fission will continuously increase in cost and the new plants being built confirm those expectations rather than the industries claims of faster build times and much reduced cost. Exponentially scaling it up looks tricky in today's setting, with a largely comatized workforce and industry. It will take time to wake the nuclear construction companies up for large scale contributions. Also, the relatively slow innovation cycle of nuclear is kind of a problem for advanced concepts like LFTR. If you use the criterion of using only what we know how to do on sufficient scale, a supposed nuclear renaissance looks no less grim to me than the renewables revolution. I do see this as a reason to have strategical planning on these issues, not as an anti-nuclear argument. However, the nuclear absolutism promoted by some is too risky for me to accept. Huge grids fantasies, nuclear dominance, reality is not an all or nothing thing, but everyone has their favorite (and un-favorite) technology I suppose.

As the saying goes: planners are condemned to use yesterday's solutions to today's (or tommorow's) problems.

It is going to take some time to get a nuclear build going. EDF puts present European capacity at 1 reactor a year, and hopes to build that up to about 3 reactors a year over the next few years.
A lot of expertise was allowed to rundown.

Just the same, in the 70's France was able to build 5 reactors a year, and the difficulties are of a different, lower order to building a totally new system such as really large use of solar thermal.

We have thousands of reactor years of experience in running reactors, and the new Areva design for instance does not differ fundamentally from prior designs.

Difficulties have been overcome speedily in China, and the Westinghouse design there has been building on time and budget.

Most of our problems in the West seem to be institutional rather than fundamental, with complex and multiply redundant authorisation processes and so on.

The same goes in spades for new reactor designs.

That is not to say that there are not real difficulties, chief amongst them financing something which takes so long to come on line.

Even with the worst figures available though, using those for the Finnish reactor, I can't make the cost anywhere near as great as for offshore wind:

At $6billion for a 1.6GW plant, if you assume a 80% capacity factor which is much lower than most current practise, you come out to something like $5 million MW, whereas estimates for wind, bearing in mind that costs change almost daily, are around £80 billion for a nominal 40GW:

Even with a healthy chunk of 7GW of this being the far cheaper on-shore wind, that is £2 million MW.
If you allow a capacity factor of 35%, that is around £5.7 million MW, or at current exchange rates $8.5 million MW

To get it that close I have made every assumption which is negative for nuclear, and all positive for wind.
In practise a series build for nuclear and a trained workforce will surely reduce costs, as the French found in their last nuclear build.

That is not the same as running costs, but off-shore wind is going to be much more expensive to maintain than on-shore, so it cuts both ways.
There are also substantial extra transmission costs and back-up needed for wind, although of course some back up is needed for nuclear.

I've got no objection to off-shore wind, if anyone can figure out how to reduce the costs from the stratospheric.

I always find it amusing that nuclear power advocates claim solar isn't competitive even though it is significantly cheaper than nuclear power when decommissioning costs are included.

Nuclear power is a dead end that is best forgotten.

Grid technology is proven and there is no technical impediment to building super-grids.

They will be cheaper and more effective over any sensible time frame and we should commence work on them now.

Thankfully grid modernisation and expansion seems to be top priority for the incoming Obama administration in the US.

That is not so amusing as some solar advocates pushing for it's use where it is not sunny.

I prefer to stick with discussing things that we actually know how to do, which include solar for residential hot water in most climates, solar thermal likely enough where it is needed for peak use and it is very sunny, and nuclear where it isn't.
As different power sources are proved at a reasonable scale that is when proper consideration can be given to their more widespread use.

A whole country, France generates most of it's electricity from nuclear, and there is precisely nowhere that is running extensively on solar thermal, so you are merely presenting unconfirmed hypotheses, which is not very useful when serious attempts to provide power are needed.

The European supergrid proposal with substantial north african solar inputs meets the requirements (for Britain as well as sunnier locations), can be built today and is far superior to dirty, expensive nuclear power.

You need to move beyond the visions of the 1950s (I know - you can't and you probably get paid to do nuclear PR and thus have no wish to try).

Porosity and dissolved minerals are not so much the problems for the current Australian test sites. They are are heat reservoirs of radioactive granite overlain by insulating sandstone cap rock. I suspect the natural convective heat flux of the granite is of the order of a watt per square metre which will be the steady state after the heat pool is 'mined'.

I think the proposal is to have two 'upholes' within a few hundred metres or so of every 'downhole'. At depth the water pathway is created by hydrofracturing, thus making an analog to the firetube type of boiler ie fluid pipes through a hot chamber. The 'steam' is more akin to froth from an expresso machine.

A major non-development is that a high profile project was supposed to be running by late 2008 which is now. It was supposed to light up a small outback roadhouse town which doesn't have artesian water below it. So far zilch.

The Cooper Basin pilot plant is due for completion in February and to be operational on March 31. Geodynamics have also received funding to build a plant in the hunter Valley, with completion due in 2012.


Geodynamics have a bunch of new holes well underway in preparation for larger scale plant construction in the Cooper Basin (see their ASX announcements page on their web site for progress reports).

Petratherm are planning to start construction of their SA plant in May.


The first US test is expected to start soon, near Reno Nevada :


Petratherm is within half an hour's drive of Beverley and Four Mile in situ uranium leaching sites. How come the anti-nuclear crowd doesn't object?

Partial answer; hot rocks are radioactive decay, nukes are fission. Both potential health hazards though.

Geothermal cycles mildly radioactive water through a closed loop to generate power. The water never leaves the site.

Nuclear power involves mining uranium, transporting it, concentrating it and putting it through a reaction that creates far more dangerous isotopes like plutonium, which then need to be stored somewhere.

The 2 aren't remotely comparable in terms of hazard, which is why the vast majority of people support geothermal power and oppose nuclear power.

Of course some plutonium ends up as the ionising source americium in smoke alarms, perched inches above peoples heads as they watch telly.

When geothermal produces 20% of a nation's electricity (outside of Iceland) we'll know it's ready for prime time. Meanwhile we'll just burn billions of tonnes more coal.

New Zealand ? Indonesia ? The Phillipines ?

I believe NZ electricty generation is about 7% geothermal but that was before Kawerau opened. I think the demand for power in NZ is about 4500MW averaged over the year. The figure banded about for available capacity of NZ geotehrmal seems to be 1500MW. I belive that at the moment it is about 380MW installed plus the 90MW of Kawerau. Of course NZ will always have hydro and wind as well. The Labour goal of 90% renewable generated electricty in NZ was very achievable.

The Philipines may be about 22% geothermal.

The USA average power draw is more like 450,000 MWe. Yet it has substantial geothermal capacity installed, something like 3000 MWe. Which offers perspective on the scale of the problem; percentages won't cut it. We need hard NegaWatts and then hard GigaWatts. Cutting US average draw to 400,000 MWe for starters will make a 100,000 MWe average geothermal production count for 25% of US electric needs. For NZ it's much easier to get a larger percentage geothermal.

The sustainable geothermal heat flux is less than 0.1 Watt/square meter at the earth's surface on average. So the sustainable geothermal resource isn't huge. However there is a huge amount of geothermal heat stored over many millions of years. When viewed as a non renewable but very clean transitional energy source, the geothermal potential is massive.

... it sounds like the most workable scheme would involve a grid of injection wells and a similar grid of recovery wells, the fluid (no doubt water?) ...

D.W. Brown says CO2 could work.

It wouldn't dissolve so much stuff.

--- G.R.L. Cowan (How fire can be tamed)

Sounds promising, but you'd have to be absolutely sure no large scale leaking of the CO2 occurs. CO2 in high concentrations is highly lethal.

Would nitrogen be suitable as well?

I suspect that the flow losses for nitrogen would be too high.

Just a note on this:

(it has been compared to a "refrigerator compressor running backwards").

The turbine in question is also used as a vapor compressor for a refrigeration system (see Wednesday at Clean Tech 2007, search for UTC).  It isn't comparable, that's exactly what it is!

Yeah, this uses off the shelf refrigeration equipment in modular assemblies. Pretty cool eh :)

One promising near term market for low temperature geothermal would be as a preheater in fossil fuel fired baseload powerplants, heating up the feed water leaving the condenser, just before it enters the boiler for re-heating. Saves fossil fuels directly without the cost of the low temperature power cycle and cooling equipment. Plus there's powerplant personel readily available so O&M should be cheaper. Considering the constant output, integrating 10% or more shouldn't be a problem. For smaller fossil fired plants the limit would be the smaller portion of preheating compared to the boiler heating requirements. For very large fossil fired plants the limit would probably be the heat extraction rate from the geothermal well.

This could be a very lucrative method of increasing the know-how and experience with drilling and maintaining geothermal wells, improving the prospects for more advanced (eg deep) geothermal in the future.

It also looks like the Purecycle can be used as bottoming cycle for existing higher temperature geothermal plants. The Geysers in California should be very suitable. Existing nuclear powerplants also look very suitable for bottoming cycle upgrades. As an added benefit, less cooling water is used.

Hopefully we do something useful with the 'waste' water. We're already going around and capping free-flowing GAB wellheads because the GAB is losing too much water.