Welcome to the Energy Blog

  • The Energy Blog is where all topics relating to The Energy Revolution are presented. Increasingly, expensive oil, coal and global warming are causing an energy revolution by requiring fossil fuels to be supplemented by alternative energy sources and by requiring changes in lifestyle. Please contact me with your comments and questions. Further Information about me can be found HERE.



After Gutenberg

Clean Break

The Oil Drum


Blog powered by Typepad

« Applied Materials Aquires HCT and Introduces Integrated Thin Film Production Line | Main | Volvo Introduces Plug-in Concept »

September 07, 2007


Rick Adair

A note of clarification re: CO2. The Glitnir report says geothermal emits 35 times less CO2 than coal-fired plants. This statistic refers to geothermal plants that generate power by directly using steam (rarely) or flash some of the geothermal brine to steam (much more common). Plants using binary-cycle technology, which is a closed-loop system that returns the brine to the geothermal resource after extracting the heat with a heat exchanger, release no CO2.

From a 2004 U.S. Department of Energy geothermal primer, the average CO2 emission from flash plants is 60 pounds per megawatt-hour. For “new” coal and gas plants built since 2002, it lists 2,069 lbs/MWh for coal, and 850 lbs/MWh for combined-cycle natural gas. The coal-to-geothermal ratio is 34.5, or about 35. (A pdf of the primer may be found here, and the emissions portion with hard-to-read charts can be found here.)

David Grenier

Plus - though its outside the scope of this article - geothermal heating and cooling on individual homes/businesses can help vastly reduce the demand for energy - whether its heating oil in the Northeast, electricity for AC throughout much of the country, or even natural gas. I'm not sure how much crossover there is between the two technologies, but I can only hope that more investment in one technology will lead to improvements that will generally make the other more accessible.


It is great to see this investment being made in a clean energy source. However, I think they had to dig to find a chart showing geothermal costs less per kwh than hydroelectric. I guess they are only considereing "small" hydro sources here. They also conveniently ommited nuclear which is cleaner and cheaper. This report looks a little biased. Still it is good to see geothermal is getting a large investment.

Kit P.

Geothermal is a good way to make electricity. I would not consider geothermal as either cleaner or more environmentally friendly than say coal.


Hi Kit,

Gee, I thought geothermal was rather clean. I suppose if the process releases steam from underground reservoirs it carries elements into the air. I searched for more information about this specific process but found little. Perhaps the best attribute is it does not use fossil fuel even though it adds CO2 and other elements “pollutants” to the atmosphere.

Rick Adair

Kit, don't know why you would think geothermal isn't cleaner than coal.

For starts, with lower temperature geothermal resources, binary-cycle technology, which is closed-loop, has no emissions of any kind, so all the emissions are from flash-steam geothermal.

Comparing this and newer, more efficient coal plants (average emissions; see previous post for reference):

Coal = 2,068 lbs/MWh
Geo = 60 lbs/MWh
ratio ~ 35

Coal = 3.6 lbs/MWh
Geo = 0.35 lbs/MWh
ratio ~ 10

Coal = 3.0 lbs/MWh
Geo = none
ratio ~ infinite

Geothermal looks a lot cleaner than coal to me.

Thomas Blakeslee

I'm glad to see that somebody is finally going to put up the money to really put geothermal on the map. The latest US energy budget reduces spending on geothermal to zero! Ormat (ORA) is an experienced, profitable company with a market cap of $1.5 billion but they are very conservative. They pay as they go and even pay a dividend. Somebody needs to get aggressive and start spending some real money on this promising technology. It is reliable, clean and has no fuel costs.

Kit P.

Johnbo, most are for renewable energy because they are against coal or nukes while the environment impact of renewable energy. Hot water from deep in the earth is going to carry all the dissolved minerals. It is a huge leap to consider CO2 a pollutant. Start a list of things that are bad for people or the environment, then list the impact.


"It is a huge leap to consider CO2 a pollutant. "
Yeah right. And the arctic ice isn't at record low levels....

But he is correct that most renewable supporters don't like Nuclear -Or even Carbon-Capture and Storage. The later is estimated to add $.03KWhr to the cost of coal derived energy (but we haven't tried to do it on a large enough scale to have that pinned down). So Kit if you want to boost coal, just take Coal plus CCS, as a baseline cost to compare against renewables, I don't think the economics will be too unfavorable for keeping old King Coal in the mix.

From a climatologist's perspective any zero or low CO2 emmisions method, whether it be solar, wind, wave, geothermal, nuclear, or CCS is very nearly equal. I hope we can develop all of them.


Nicely put bigTom for a climatologist’s point of view, however you left out hydroelectric. From an energy efficiency viewpoint hydroelectric and nuclear are the winners. Each of these pays back 50 or more times the energy required to build and maintain them over their life. I believe we green folks should support all of them. JohnBo

Kit P.

The most irritating thing about environmentalists is their collective ignorance of the environment. And no, artic ice is not at record low levels. It is however a huge leap of logic to blame CO2.

Many environmentalists like to put insignificant environmental impacts like climate change, radiation, PCBs, and mercury at the top of their lists.

It Glitnir hired me to do ‘due diligence’ on a geothermal plant, I would want to know how the plant is handling ground and surface water contamination, arsenic as an industrial safety issue, and piping corrosion as an economic issue.

My list starts with real environmental impacts. If the project can economically produce electricity while protecting the environment then start the PR campaign that discusses air emissions.

I think the bankers at Glitnir are in for a rude awakening. Just because geothermal is environmentally friendly in Iceland does not mean the US NIMBYs will not try to stop projects.

Again, Geothermal is a good way to make electricity.


Kit and I disagree on climate, but we do agree that geothermal is a good energy source. And yes the NIMBY stuff often stops some good projects. Too often environmentalists see only the local impacts, ignoring the global impact of having another less clean energy source being built elsewhere to take up the demand not satisfied by the local project.

JohnBo: I meant to have hydro on the list. Now large scale hydro can have some serious impacts due to the flooding of land, and methane emmisions from decaying drowned vegetation. Large scale hydro, may actually liberate more GreenHouse gases (mainly Methane) than it displaces. Of course knocking down existing dams is different, we have already paid for their environmental cost, and it would usually be best to continue producing power.

Incidentally quibbling about the few percent (of Coal) carbon emmisions of these alternatives is really pretty silly. In the worst case the small amounts liberated could be handled by free-air capture without hugely impacting the cost.


Hi bigTom,
I have no evidence but intuitively it would seem that methane release from man made lakes would be minuscule compared to all other natural bodies of water. This seems like a poor argument for not making more power-producing dams. JohnBo

Marshall Ralph

I appreciate Kit P's admirably skeptical concern with material performance (dissolved mineral emissions, piping corrosion, etc.) of geothermal power plants. As it happens, most geothermal plants (the binary and flash ones) do pretty well on the dissolved mineral handling score, since the resource fluids containing the dissolved minerals are nearly all injected back into the ground, typically into the periphery of the formation they arose from, minus some heat and, in the case of flash plants, the fraction of water that is "boiled off" in separation. Dry steam and geothermal plants typically emit water vapor and varying fractions of noncondensable gases such as CO2, CO and H2S. Piping corrosion and scaling are generally handled in fairly pedestrian ways. There are some few areas that pose interesting exceptions to typical practice sketched above – areas where the brine is exceptionally rich in dissolved stuff: silica and some metals. These operations can yield some thought-provoking waste products that would rightly pique Kit P's interest. But in the U.S., these tend to be anemable to standard industrial and environmental practices.

Kit P

“But in the U.S., these tend to be anemable to standard industrial and environmental practices.”

Well said! This is why geothermal is a good way to make electricity but creating hazardous waste requiring health physics supervision takes out of the realm of clean energy.

Marshall Ralph

Kit P, you make a fine point, and I thank you for your rigor in looking at performance rather than fashion. I am a partisan of geothermal, so I'll gently urge you to consider that most geothermal plants don't end up with masses of precipitates on the surface. That's kind of a rare situation, so maybe a quantitative lookover of a bunch of different plants and processes would temper your conclusion. That would be an interesting paper. I also suspect that there is some growing maturity (and more solid capitalization) in the geothermal industry in the past decade that has resulted in better housekeeping practices incorporated in new plants. New plants I've seen look pretty tight. That wasn't always so, I blush to admit. I will now STF up. Thanks for your thoughts.

Kit P

Marshall, I completely agree and I too am a partisan of geothermal. Making electricity is a dirty dangerous job and it takes good design and operation to deliver a product safely with minimal environmental impact.

My 'dirty' geothermal data point comes from one of the worst managed utilities in the US. One of the places that no one claimed to eat off the floor.

I would enjoy some more recent geothermal info if you have it.

ambit energy

Amazing blog and very interesting stuff you got here! I definitely learned a lot from reading through some of your earlier posts as well and decided to drop a comment on this one!

NFL shop

I would like to thank you for the efforts you've made in writing this posting.

Core Drilling Machine

Thanks for sharing the information with us..it is worth reading..And i completely agree with your point..

The comments to this entry are closed.

. .

Batteries/Hybrid Vehicles