Saturday, February 21, 2009

How much would an all renewables electrical system cost?

The Gore plan, the Google plan, the energy writings of Joe Romm, the views of the Internet site Gristmill, and other self proclaimed energy authorities, all maintain the view that an all renewable grid is possible.  Some time  ago I attempted to evaluate the theory of reliable wind suggested by Mark Z. Jacobson.  Jacobson argued, based on empirical data from 17 sites in the southwestern Great Planes, that wind generation could be made reliable by building grid links between those sites.  Jacobson found that the linked sites could be expected to produce at least 20% of their rated capacity 80% of the time.  Jacobson further argued that this reliability approached that of base generated electricity.  My analysis, using a 2008 wind cost estimate of $2500 per KW, and evaluating the Google energy plan, found that the 380 wind GWs called for by the Google plan would cost $900 billion to install,    This estimated installation cost did not include the expansion of the grid that would be needed to transmit the electricity from the windmill array to consumers.   I found that the linked wind array could be counted on to produce about 80 GWs of electricity 80% of the time.  The linked wind system, however, had a serious flaw.  It could not deliver power on hot summer days when electrical demand peaked.  

I undertook a comparison between the Google wind proposal and  an alternative scheme to build nuclear reactors at the same combined cost as the wind array.   I estimate at $900 Billion dollars would purchase 112 one GWe reactors.  At a .90 capacity factor, the reactors could be counted on to deliver 101 GW of electricity at any time.  Or a little over 20% more electricity at any given time than the wind array.  Unlike the wind array, the reactors could be counted on to deliver electricity at close to maximum capacity on hot summer days.  

In addition I offered evaluations of the cost of wind with three energy storage plans.  The use of batteries, to store wind generated electricity, the use of pumped storage, and the use of Compressed Air Energy Storage (CAES).  My CAES study was in turn based on  "The Economic Impact of CAES on Wind in TX, OK, and NM," by Ridge Energy Storage & Grid Services L.P, for the Texas State Energy Conservation Office. in 2005. I assumed .40 wind capacity factor and that 40% of the energy output from the CAES system would come from the burning of natural gas, a standard assumption for CAES systems. The Ridge Energy study showed that electricity could reliably dispatched on a 24 hour a day basis from a CAES system on a 24 hour a day basis, even during low wind summer days, demonstrating the viability of a Wind-CAES system, However, the energy output of CAES systems is .80 of energy inputs. This suggests that there are considerable in efficiencies in the use of wind generated electricity by the wind CAES system, and that at least 30% of the electrical input is lost to system inefficiencies. Ridge Energy estimated that the capital cost of a CAES system would run @$765 per KW, an exceedingly modest sum, but one which should be examined. The capital cost for source wind array combined with the CAES system is in fact much higher.

I stipulated a cost for new West Texas wind of $2250 per name plate KW in 2009. This price was at the low end of 2008 windmill costs in North America. Since the capacity factor of West Texas runs around .40, the adverage output West Texas wind producer can expect to pay $5625 for every KW of electrical producing capacity. Since only 70% of the electricity entering the CAES facility reaches the consumer, the wind producer must increase his wind generating capacity by 30% to compensate for the energy loss. Thus the price of the wind generated electry entering the CAES facility must compensate the wind producer for something like a $8000 capitol investment for every average KW sold by the CAES facility. When added to the $765 per KW capital investment in the CAES facility, and the cost of natural gas used with CAES technology, we get a very ugly picture, of the cost of wind generated electricity.

In my pumped storage study, I reviewed the cost of the Northfield Mountain Pumped storage facility in New England. I calculated the cost of the 1080 MW facility at 3.7 billion 2008 dollars using the 1972 cost and a standard conversion table. I noted that an estimated 2008 cost for a reactor of similar capacity would be around $5 billion. The pumped storage facility had the ability to deliver power for 10 hours at a tome, while the reactor could be expected to deliver power continuously at least 90% of a year.

In order to produce electricity for the pump storage facility, a wind generating array would have to be built. The cost of that array would be paid for when electricity from the pump storage facility was sold. Pump storage operates at 75% efficiency. That is 25% of the energy input is lost before electrical output. Thus assuming a very generous West Texas capacity factor of .40 for the wind array with a rated output of 1400 MWs operating 24 hours a day would be required to fill the pump storage facility. Lets assume costs at the low end of the 2008 range for windmills, say $2250 per KW. Thus the wind array required to fill the pump storage facility full would cost $3.150 billion. That would give us a figure of close to $7 Billion to be financed by the sale of peak electricity from the pumped storage facility. Seven billion dollars is a l;arge investment for electricity that would be only available for 10 hours a day. Since as reactor capable of producing a similar amount of electricity 24 hours a day could be had in 2008 for 2 billion dollars less, the reactor is the better deal.

Finally, I examined battery storage with wind. Battery storage appears to be the most expensive electrical reliability/storage systems. After producing an estimated cost of Wind + battery storage, i then looked at the cost of a non-storage backup system for wind, a conventional nuclear reactor. The reactor was actually less expensive than a combination windmill battery backup system In addition the nuclear system would be so reliable that wind generation could be dispensed with and the system rely entirely on nuclear power.

Post-carbon electrical generating systems require reliability. During the last few months I have produced 4 case studies of the cost of making wind generated electricity reliable through the use of different technologies. Renewable advocates often complain that nuclear power is too expensive. My assessments show that reliable wind capital costs would more expensive than the capital costs of nuclear generated electricity in any of the noted cases. Facility costs for PY and ST power would be considerably higher per KW than wind in any of the noted cases. Given that the capacity factor for Southwestern Solar is not much higher than .20, it seems likely that reliable solar would be even more expensive than reliable wind, however, since I have not studied the economies of solar storage systems this is impossible to confirm.

My current research has not focused on other hidden cost of renewables generation. These include the cost of new transmission lines that are required by renewable generation systems, to be born by rate payers, the cost of federal and states tax based subsidies, the cost of keeping grid voltage stable. None of my case studies would support the contention that the cost of reliable wind would be competitive with conventional nuclear as a source of reliable electricity.

My conclusions have been acknowledged by some of the more sober minded supporters of the renewables paradigm. It is my contention then conventional nuclear power will cost less than reliable renewable electricity in a post carbon grid, and that National energy priorities ought to be rethought in light of the evidence that conventional nuclear power is the lower cost option. If conventional nuclear power is too expensive, then renewables are even more expensive. Thus we need to find a lower cost electrical generation option.


Bill said...

Have you run the numbers for solar thermal with storage? How to Use Solar Energy at Night (Scientific American) claims

"All told, that means thermal energy storage at Andasol 1 or power plants like it costs roughly $50 per kilowatt-hour to install, according to NREL's Glatzmaier. ... Electricity from a solar-thermal power plant costs roughly 13 cents a kilowatt-hour, according to Glatzmaier, both with and without molten salt storage systems."

bobcat said...

At least here in Southern California, solar thermal plants will be used for generating electricity when it is needed the most, which is during the day. So they will not be competing against nuclear energy but natural gas instead. Depending on the economics, which I am sure Charles will soon be running the numbers, solar thermal energy will complement nuclear energy, not supplant it.

A nuclear/solar economy will drive the greens crazy. That in itself would be enough to pursue that option.

Bill said...

Bobcat: "So they will not be competing against nuclear energy but natural gas instead."

Yeah, I made that point in a discussion on the New York Times:
Wind and solar compete with gas;
nuclear and geothermal compete with coal.

donb said...

Charles Barton wrote:
The Gore plan, the Google plan, the energy writings of Joe Romm, the views of the Internet site Gristmill, and other self proclaimed energy authorities, all maintain the view that an all renewable grid is possible.

Perhaps Al Gore, Joe Romm, or some other prominent person who makes such a claim would be willing to live it. Simple enough: Select (for example) a group of wind turbines near the volunteer's home. Monitor the generation of those wind turbines, and make available (via a Smart Grid device!) an amount of power to the home proportional to the generation of that source. When it comes time for billing, the charges would be equal to the feed-in tariff for the wind turbines PLUS any wind generation subsidy.

If the intermittant nature of the power is not acceptable, the volunteer can install his own batteries, or be charged for the additional electricity at a rate equal to the generation costs via renewable, plus the storage costs.

Somehow, I don't think these folks will be standing in line to sign up.


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