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Welcome American Scientist readers

Thursday, July 1st, 2010

American Scientist Cover

The July/August 2010 issue of American Scientist magazine has a ten-page article, Liquid Fluoride Thorium Reactors, by Robert Hargraves and Ralph Moir. The article ends with a link to this web site, so welcome to you and other newbies.

This redesigned site is rich with information; here’s a guide for those with inquiring minds. Start at the very top of the page at the eight links in lower case separated by bars. Click on “about” for a short introduction to thorium, the research history, and a graphic representation of the liquid fluoride thorium reactor, LFTR.

Click “msrp” to read the summary of the molten salt research program at the Oak Ridge National Laboratories in 1958-1976, where these nuclear reactors ran. Click “plan” to read Kirk Sorensen’s vision of a deployment strategy that starts up a global fleet of LFTRs using up the fissile material from spent fuel “waste” and excess weapons.

In the right hand column under “Pages” are a timeline, a LFTR fuel cycle summary, and a plea to save the DOE’s U233 slated to be destroyed.

Under “Top Links” is the cited online forum, where engineers and scientists openly exchange ideas about LFTR technology. If you would like to contribute your knowledge, spend some time reading the posts in your area of expertise, register, and post.

Also under “Top Links” is the rich “PDF Document Repository” which is an index of all the LFTR R&D done by Oak Ridge National Laboratories, plus many recent papers by current researchers worldwide.

Scroll down to explore more of the right hand column links, pausing at “Archives” to peruse earlier posts to this blog.

Welcome to American Scientist readers and all newbies at Energy from Thorium.

Energy Cheaper than from Coal

Tuesday, March 23rd, 2010

I look forward to presenting Liquid Fuel Nuclear Reactors talk at the Thorium Energy Alliance symposium at the Googleplex next week. Part of that talk will remind us that the liquid fluoride thorium reactor is capable of producing energy cheaper than from coal.

Cap and trade and carbon taxes have faded from public attention. No agreement was reached in Copenhagen because the developing nations would not accept taxes that limited their potential for economic growth. From their point of view, the OECD nations achieved their wealth from cheap energy, from burning coal.

A way to dissuade nations from burning coal is to provide an economically superior alternative. If the LFTR can undercut the economics of coal, nations will build LFTRs and stop burning coal — all this without punishing carbon taxes and fraud-prone carbon credit trading. In the US the average cost of coal delivered to a utility is $40/ton, which works out to 2 cents/kWh just for the coal fuel. Depreciation and operating expenses double this. In China electric power is delivered at 5-7 cents/kWh to the industrial and commercial centers; I suppose [coal] power generation costs are half that. I propose a target for LFTR power of $0.03/kWh, from the power plant. This is an ambitious, achievable target, because of its unique, low cost attributes of compactness, intrinsic safety, and high temperature. I’ll present these next week.

Overpopulation, global resources, and wars over them are as critical to civilization survival as is climate change. Population is projected to climb from 6 to 9 billion people. Nations refuse to protect the few tuna left in the oceans. Mid-east wars over oil are fresh in memory.

Yet population growth is stable in the wealthy OECD nations; children are born at less than the population rate. Analyzing data from the CIA World FactBook shows that prosperity stabilizes population. At a GDP of $7,500 per capita, birthrates fall below the replacement rate. Fewer people competing for scarce global resources will stabilize the earth’s civilization.

Energy is a critical element of achieving prosperity. Prosperity also depends on food, education, health care, rule of law, a stable financial system, and good government. Consider the importance of electric power. It is essential to water distribution, sanitation, lighting, cooking, heating, refrigeration, communications, health care, and machinery. Prosperity helps people spend more time in productive jobs, becoming more educated, and having some leisure time to enjoy life. Freeing women from constant toils of everyday life allows them time to become educated, contribute to the paid workforce, and make choices about bearing children,

Providing power at $0.03/kWh makes energy affordable to developing nations. Another unique attribute of the LFTR is its ability to be produced in small sizes at affordable investment levels — $200 million for a 100 MW LFTR will meet the $0.03/kWh target. The CIA World FactBook data above shows that 2,000 kWh per capita per year suffices for modest prosperity. For comparison, the US uses 12,000 kWh per capita per year.

Energy cheaper than from coal is critical to civilization for two reasons: (1) stopping CO2 emissions from burning coal is a big step to controlling climate change, and (2) affordable electric power is key for developing nations to achieve modest prosperity and the lifestyles that include stable birthrates.

How to save $46 billion per year

Saturday, October 24th, 2009

I attended the Thorium Energy Alliance meeting in Washington DC last week to present my submitted response to the ARPA-E, August 31, Request for Information about energy ideas such as “disruptive new approach to…thermodynamic power cycles.” I have to publicize this myself because DOE promised not to respond to submissions! I believe the responses help DOE plan and budget future Requests for Proposals, where money is actually granted. So get your grant writing hat on.

The illustration above is from the DOE Annual Energy Review for 2008. It’s a bit busy, so I extracted the interesting numbers, below.
The diagram above illustrates how electricity is produced from thermal sources such as coal, natural gas, and nuclear power. Note that the thermal/electrical power conversion efficiency for the US is just 30%.
Engineers know that efficiency is limited by the Carnot theorem to (Tin-Tout)/Tin, so raising the temperature of the fluid entering the power conversion turbine can raise efficiency to 50% or more. High temperatures are an advantage of the liquid fluoride molten salt reactor, and also the high temperature gas reactor, concentrated solar, and the molten salt cooled pebble bed reactor. In a power plant the thermal/electrical power conversion system can cost as much as the heat generation system itself.

The triple-reheat closed cycle Brayton turbine power conversion system has been proposed to utilize high temperature fluids and create electrical power at efficiencies >> 30%. It can achieve 45% at 700 C, over 50% at 900 C.
The problem is that the triple reheat closed cycle helium gas Brayton turbine has not been demonstrated at power plant scale. The test rig at Potchefstroom, South Africa, was supposed to be the first such unit, but the pebble bed modular reactor project has been scaled back because PBMR Pty Ltd has run out of funds. Rolls Royce was a contributor to this work. Many theoretical papers have illustrated the value of this technology, with contributions from Oak Ridge National Laboratory, Sandia, and Idaho National Laboratory, for example. The rub is that there is no demonstration plant for this technology.
The GE LM6000 turbine above is just one of hundreds of examples of commercial gas turbines that utilize the Brayton thermodynamic power conversion cycle. But these are all open cycle turbines. The technology experience can be transferred. The closed cycle turbine should be easy because it operates at a lower temperature, without internal combustion and its products. It’s harder because it needs a input heat exchanger, a rejected heat exchanger, and a helium gas reservoir and polishing system. Alternatives to helium include nitrogen or carbon dioxide.
Investing $500 million could save $23 billion per year
A SWAG development cost might be $500 million. Organizations that could contribute to this work include GE, Pratt & Whitney, UC Berkeley, NASA, MIT, Sandia, INL, ORNL, and Rolls Royce. The savings result from reducing rejected heat. This technology can HALVE the rejected heat in the US, by raising thermal/electrical conversion efficiency from 30% to 46%. Rejected heat for the US in 2008 was 26 quads. Creating this heat would cost $46 billion if it came from coal, or $183 billion if from natural gas.
The liquid fluoride thorium reactor is a thermal source that enables this savings. I advocate that the DOE fund development of the triple-reheat Brayton cycle closed helium gas power conversion system because it supports LFTR and other technologies as well.
So be prepared to write proposals when the DOE issues its next Request for Proposals.