amazngdrx always has opposed geothermal “because it injects fresh water into underground rock faults and uses the resulting steam, losing most of the water in the process.” Furthermore, there is the “possibility of contaminating aquifers with mineral bearing sulphate rock leechate from escaping steam.”
That so much water is lost with conventional, utility-scale, geothermal power was news to me. It is my understanding that such consequences could be severe with another geodynamics project, i.e., the still experimental, commercial development of Hot Dry Rock / Hot Fractured Rock (HFR) power.
Given that water goes for tar sands processing and tertiary loop for nuclear reactors, not to mention the sludge hitting the rivers, it still seems like amazng “is taking the high moral ground.” Yet the advocacy of amazngdrx is generally thoughtful, so it did give me pause to reconsider my mild (as compared to a strong advocacy of ground source heat pumps) advocacy of utility-scale geothermal.
Photo: David Calvert / Ormat Technologies Inc.
Ormat Technologies’ geothermal power plant in Reno, NV.
Such development of sustainable, utility scale, energy supply occurs in geologically active locales scattered throughout the Western and Southwestern United States, and in:
This blog has relayed several reports from the Peak Energy blog about geothermal power and further development certainly is underway. For instance, this blog recently noted that Raser Technologies, Inc. had increased their total holdings for geothermal, surface and other rights to over 300,000 acres in five states. “It is imperative to our country’s energy independence and for the health of the environment,” claimed Raser senior VP Dick Clayton, “that these geothermal resources be developed as rapidly as possible to meet growing energy demands.”
Somewhat gratifying was amazng’s acknowledgment of an idea that I previously considered, i.e., to combine geothermal with solar thermal power.
A brilliant commentator in Gristmill [Editor's Note: Not this brilliant commentator, some other brilliant commentator] came up with a new idea.
He suggested teaming hot rock steam with solar furnace steam. That way the rocks get to rest and recuperate when the concentrating solar plant is powering the turbines. Molten salt storage could use solar even at night, cutting the time/heat needed from the hot rocks. The rocks lose their heat after 10 years of constant operation, this symbiotic design cures that.
The beauty is that the turbines are powered by both sources.
All water would need to be recycled from both solar and hot rocks, a closed loop of pipe would be needed, to deal with high water use objections. Furthermore extra power produced that can't be used by the grid should go for waste water filtration and desalinization, actually making this system a big net water producer.
The design could use long drill pipes going down into the hot rock, then a smaller spray pipe that goes down the center. The water would spray on the hot pipe and the steam would come up into the turbines, then be recondensed with ground source cooling. Recycled 100%, barring a leak here or there.
The ground source cooling loop could heat a greenhouse or factory or mall, storing the heat seasonally under the building. Cool desert climate like Colorado might use this.
The big plus is that this combined system provides a stable base load, something to count on in case of wind or solar dips. And it provides huge peak surpluses that can go to stored heat/cold in building mass and fresh water production. That water is renewable energy stored as a valuable commodity, vastly enhancing the financial model. And shortening the payback period.
This feature would attract capital from desert nations especially, think oil rich nations. Water is the oil of this century. That justifies over building wind and solar energy capacity. It can always be used profitably to reclaim waste and sea water.
4 Comments
Writing the Peak Energy Blog, His Toothiness, the Big Gav notes in a recent post some of the pros and cons to further development of utility-scale geothermal power.
As long as we are looking for clever places to put concentrating solar power stations the most obvious, and most ignored is belly up to existing coal-fired power plants. This isn’t as insane as it sounds. We want electricity, which we get by spinning generators, attached to turbines, propelled by the expansion of hot gases, usually steam. We produce the steam by burning coal.
CSP plants produce steam but only for partial days. Installing turbines, grid connections, voltage converters and so forth is probably a significant portion of the cost of a new CSP plant. If we could eliminate that half of the cost, even at a loss of 30% efficiency, we’re ahead. The combined plant could operate like this:
Solar/Steam+Coal/CO + CH4(producer gas) boilers OR gas
turbines OR gas-to-liquids electricity.
But since we have a rail head and we don’t want to produce coal ash we also have the option of this:
Solar/Steam+biomass/CO + CH4 boilers or gas turbines or gas-to-liquids electricity. or Solar/Steam + biomass + pressure CO + CH4 + biochar boilers or gas turbines or gas-to-liquids electricity + carbon sequestration/soil amendment.
With the producer gas stored in low pressure tanks for several days supply suddenly your dirty coal plant becomes a LOT more efficient any day the sun shines or any day that a supply of urban green waste can be secured. Existing infrastructure is retained instead of duplicated or abandoned. Coal usage is decreased by the amount of sunlight that can be collected and the CSP plant trades siting efficiency losses for use of existing grid ties, rail heads, turbines and trained staff.
The, stupid, 24/7/365 objection to solar power supplies simply gets tossed. Producer gas can be made with sewage sludge and low temperature steam should the sun hide for a week, simply at an efficiency loss. If all else fails in a weather emergency one could always burn some coal.
Of course, you have to use big government to confiscate and operate the power plant but the capitalism myth is getting crunched under the hobnail boots of reality anyway. There is that factor that coal plants come in gigawatts while CSP plants come in megawatts but since the production of the CSP units could be steam OR producer gas a string of plants along a rail line could pipe gas and/or steam down to the turbine plant depending upon proximity.
Why shut down the coal plants when we can use them as solar plants?
Great minds think alike: "http://my.epri.com/portal/server.pt/gateway/PTARGS_0_237_317_205_776_43/http%3B/uspalecp604%3B7087/publishedcontent/publish/epri_to_evaluate_adding_solar_thermal_energy_to_coal_plants_da_625473.html" rel="nofollow">
EPRI TO EVALUATE ADDING SOLAR THERMAL ENERGY TO COAL PLANTS
(picked up at Democratic Underground) and "http://www.lowcarboneconomy.com/community_content/_low_carbon_news/4246" rel="nofollow">
Biogas From Waste Could Heat Half Uk Homes (ibid) It makes me
wonder if I’m a genius or a very slow telepath with bad focus.
New York City Treehugger George Spyros relays from the “We” Campaign a new ad that calls for Clean Energy. Such investment will help the vital transition for America to lead the way by stopping Dirty Coal and reducing our dependence upon foreign oil. The new national TV ad program calls for continued major investment in solar energy.
Says WE:
This blog and the NYC treehugger agree with out president who acknowledges that while the United States invented and developed solar technology, we have fallen behind countries like Germany and Japan in production. President Obama is repeating a challenge from ex Vice President All Gore, who said that it is time for America to lead again.