Just how much geothermal potential is in the US?
This is a question bandied about frequently in geothermal circles. Recently, a panel chaired by Jeff Tester from MIT set out to answer that question and they presented their results at the 32nd Stanford Geothermal Conference yesterday.
Let’s first setup the measurement system, it’s in exa-joules (EJ.) A kilowatt hour is approximately 3.6M joules. An exa-joule is 10 to 18th power joules, or 1,000,000,000,000,000,000 joules. The entire US electric consumption for a year is around 100 EJ. Now that this is a nice easy way to think of it, 1 EJ = 1% of annual US electricity consumption, I’ll tell you what they discovered.
That if only 2% of the US geothermal potential was tapped, we would be able to access some 28,000 EJ in electric power generation. This statement is grand and requires some explanation. There are two flavors of geothermal power, hydrothermal and enhanced or engineered geothermal systems. This combines the output of both methods and predicts that resources at deep as 10km will be exploited over the next 50 years.
Even if this estimate is wrong by two orders of magnitude, it’s still 28x our current annual electricity consumption for the entire country. That is sufficient to cause even the most jaded person to stop and think. What could we achieve if we diligently work to tap and harvest this resource inside our own borders, with no carbon emission, and maintain our energy system with baseload power? What’s the impact of simply displacing old coal plants with new geothermal plants?
The study goes on to say that they believe 100,000 MWe (generation capacity) is entirely feasible by 2050, which is only 10% of the current electricity consumption per year in the US. There’s now a nice article posted on the MIT website that references this study available here.
I’ve said it before and I’ll say it again, each megawatt hour of electricity generated by burning coal yields a ton of carbon and 14 kg of SOx and NOx into the atmosphere. To produce a new “clean” coal plant is a $1B+ investment. Fuel cost of coal has increased 35% over the past 6 years. Our ability to transport new coal in the US is constrained by railroad capacity, which is at capacity. Why invest in coal now?
Why not invest in clean power generation where the fuel is free and local. Nothing gets vented into the atmosphere (in a closed system) and start solving our dependence and climate impact. This isn’t rocket science….
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Technorati Tags: Geothermal | Potential | EGS
You know what? Even I understand that. Good break down bro. Keep up the good work.
Makes perfect sense.Tthat’s why it will not happen unless people like you step up. Keep up the great work!
Mike, the 2 percent, 28,000 EJ figure is a *very* conservative estimate of heat that is recoverable through EGS methods, not an amount of generated electrical energy.
If you have access to the report PDF, read pages 16-17 of Chapter 1 for the context of Figure 1.7, which has the numbers you cite.
Somewhat confusingly, the figure has the total US consumption of energy in 2005, without qualification of what that means.
In fact, it is there to provide an apples-to-apples comparison. That number, which is available from the U.S. Energy Information Agency (see, e.g. http://www.eia.doe.gov/emeu/aer/txt/ptb0101.html), gives the total consumption of energy regardless of use – gasoline, heating with natural gas, electricity generation, etc.
EIA gives it as “99.89 quadrillion btu”, which the google unit conversion “99.89 quadrillion btu in exajoules” will tell you is closer to 105 EJ, rather than 100 EJ of the figure. But 100 is a nicer number to work with.
To go from heat to electricity, you need to specify flow rates, water temperatures, and some power plant details. These would be site specific.
Using a back-of-the-envelope approach outlined in Section 3.5 of the report, the 2 percent recoverable heat estimate would yield about 1,250,000 net MW of electricity. A still conservative 20 percent recoverable heat would yield about 10 times this.
These numbers give the amount of electricity that can be generated at any cost. This is a very, very important point to understand. Regardless of altruistic tendencies, cost drives pretty much everything in this show. For the EGS program to succeed, it absolutely must be cost-competitive with other kinds of electricity generation.
Regulated utility purchases of power must be deemed “prudent” in order for state regulators to allow them (ie, to allow utilities to pass the cost on to ratepayers), which generally means it’s a relatively low-cost item.
Along the West coast – in California, Oregon and Washington – utilities are bringing to the regulators plans for meeting future power needs that include a cost of greenhouse gas generation tacked onto fossil-fuel-based generation – typically $5 per ton of gas – in anticipation of future national regulation along these lines. This makes renewables (mostly wind, at the present) cost competitive with natural gas and coal-fired generation in the long run, and allows regulators to sign off on making renewables part of the generation mix .
It is in this spirit that the report forecasts 100,000 MW of net electrical generation from EGS by 2050 *** at cost-competitive prices ***. This is *not* the amount that is feasible, which as we saw above is much higher. It is the amount that regulators would have no problem deeming prudently priced. In fact, in only 11 years after getting funded, the report says EGS would reach “parity” with market prices (by exploiting the easier portions of the resource, I think), a point when 240 MW of capacity would have been built out (pages 43-44 of Chapter 9).
The report also touches on the concept of “energy parks,” where combined heat and power can be provided by the same resource, an additional value from developing the resource.
Great comment, thanks Rick. I haven’t read the 400 page report as I don’t yet have access to it, I wrote this entry from the 30 minute presentation given by Jeff Tester a couple of days ago at the Stanford Geothermal Conference.
Even with the prodigous detail in your comment, geothermal has got to be at the forefront of our energy portfolio and policy. The major cost factor in geothermal systems is drilling, not all of these resources require EGS and not all of them are “deep.” The point about cost competitiveness is absolutely spot on. The average operations and maintenance costs for geothermal plants is around $0.02/kwh – competitive with fossil. Transmission is identical. Fuel prices add additional cost to fossil plus the deleterious environmental effects.
The only difference remaining is capital cost to construct. The cost of a clean coal plant is now over $1B – or around $2M per MWe. The cost for geothermal on average is $2.5M per MWe. Over the long term due to fuel cost alone, geothermal must be more cost effective for the rate payer. While there are synergistic and desirable environmental benefits, the move to geothermal in a Manhattan Project type way is in the public’s best interest from a cost and climate perspective.
You can get the full, 14.1 MB, report, from NREL:
http://geothermal.inel.gov/publications/future_of_geothermal_energy.pdf
Thanks for the pointer Rick. I guess the sign-up sheet for access to the report posted here was a ploy to get mailing list fodder!
I think I remember seeing you at the Stanford meeting. I was sitting in the back right of the main room, near a power outlet because my “laptop” battery lasts only 45 minutes.
Cool, didn’t know you were there – of course, I don’t know what you look like 🙂 Sorry we didn’t get a chance to talk in person.
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