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Are Thorium Reactors the Carbon-free Answer?

RP Siegel | Wednesday August 24th, 2011 | 8 Comments

Let me make one thing clear from the outset. I have never been a proponent of nuclear power plants. I think there are as many different reasons to avoid them as there are to avoid eating meat. (i.e. medical, political, social, environmental, and economic)


  • They are dangerous today (e.g. Fukushima)
  • The waste problem will be enormous for many tomorrows to come
  • The are incredibly expensive
  • They are not carbon free
  • They can lead to harder stuff—like nuclear weapons
  • They substitute one limited fuel for another

I strongly believe that we need to address our impending energy and climate crisis by dramatically improving efficiency and reducing demand, while at the same time bringing more and more clean and safe renewables online, preferably in a distributed manner.

But there is no guarantee that we are going to be able to navigate a smooth transition from our current wasteful, high-intensity economy to a more sustainable one on a timetable that is swift enough to adequately address our rapidly deteriorating climatic stability. As new fast-growing economies come online, pouring more and more carbon dioxide into the atmosphere, there seems to be little inclination on anyone’s part to stop for a few decades to give the atmosphere a chance to digest what’s already up there. So the CO2 levels continue grow, even as we have already crossed the maximum safe threshold of 350 ppm.

So, despite my aforementioned bias, when a friend told me about a little-known alternative nuclear energy source, that purportedly addresses all of the above-mentioned concerns and could conceivably become widely available in a short time, I thought this might be something worth considering as an interim solution.

We could use a bridge of 20-50 years to allow our existing fossil infrastructure to be gracefully decommissioned while the new efficiency and renewable supply regime develops and matures.

The use of thorium as an energy source for nuclear power plants was first demonstrated at the DOE’s Oak Ridge National Laboratory (ORNL) in the early 1960’s. The main reason it was outgunned by uranium as the fuel of choice was because it did not produce plutonium as a byproduct, which, at the time, the DOD needed, in large quantities, to fuel our emerging nuclear weapons program.

There is widespread consensus among scientists that thorium is as “a safer, cleaner and more abundant alternative fuel,” when compared to uranium. It is less radioactive and more proliferation resistant. Its reaction in a molten-salt reactor (MSR) does produce U233 but that is apparently not a weapons-grade material. Thorium is about four times more abundant in nature than uranium. The largest reserves are in Australia, India, and the US.

The modern version of the MSR is the Liquid-Fluoride Thorium Reactor (LFTR). This design is considered especially safe because of its inherent properties. The reactor core is not pressurized. Any increase in temperature results in a reduction in power, thus eliminating the problematic runaway meltdown scenario. If the fluid should get too hot, a salt plug at the bottom of the tank simply melts dumping the entire mess in to a storage vessel directly below the reactor.

The waste scenario is also quite encouraging. Thorium produces about a thousand times less waste throughout the supply chain than uranium. Then it is almost entirely consumed in the reaction. Of the remaining quantity, which is quite small (I’ve been told it’s  about the size of a coke can for every billion kilowatt hours), 83% is safe within ten years and the rest (17%) requires 300 years of storage before it becomes safe. While that is still a long time, it is far more manageable than the 10,000 years required for today’s spent fuel.

There are no other known issues. The technology is still unproven and questions remain about the economics and the specific turbine-generators that would mate with these reactors have yet to be designed. It is expected to cost far less than conventional reactors and  because of its simplicity, it can be scaled down to the point where one can be carried on the back of a tractor-trailer and used in a distributed manner.

Of course, if we look from life-cycle analysis perspective, thorium power, like all forms of nuclear power, is not truly carbon free. A good deal of carbon must be used in construction, transportation, maintenance and disposal. I’ve not seen such an analysis done, but it does appear to have a footprint that is considerably smaller than that of uranium.

While this technology was invented in the US, it is China and India that are pursuing its commercialization most aggressively. Earlier this year China announced its plan to press forward with Thorium at the Chinese Academy of Sciences. While the US DOE set up an international collaborative R&D initiative called Generation IV Nuclear Energy Systems, China has made it clear that, seeing the tremendous opportunity here, they intend to go it alone.

While I see a considerable niche for this technology as an interim solution, I do not believe that this or any other energy source should be considered the long term panacea to our societal challenges. Unlimited energy would only continue the trend of unlimited consumption on what is still a fundamentally limited planet. Land, water, raw materials and waste repositories will all eventually be exhausted unless we learn to curb our consumption and live within our means.

[Image credit/kmichiels/Flickr Creative Commons]

RP Siegel is the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water.  Like airplanes, we all leave behind a vapor trail. And though we can easily see others’, we rarely see our own.

Follow RP Siegel on Twitter.


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  • http://reserveenergy.blogspot.com/ Corey Barcus

    An important additional benefit which you omitted is that LFTR’s high temperature of operation allows it to be cooled without water, which safeguards our aquifers, rivers, and shorelines. If we pursue this technology, no other source of electricity generation can come close to competing. That alone makes this a long-term solution- for thousands if not millions of years. We need this technology now in order to drastically improve on the net energy available from power generation. Renewables essentially make us “farm” for energy because the density is so low, and this in turn affects the cost. Without very low-cost electricity, it will not be feasible to synthesize the carbon-neutral fuels and fertilizers that we need going forward, nor will we be able to economically sequester a century’s worth of carbon from the atmosphere.

    But growth has its limits, and we’ll have to confront the waste heat from power generation sooner rather than later. One ethical way to deal with this problem is to limit population growth through education.

    There really isn’t anything to keep us from aggressively pursuing the Thorium Race for Green Nuclear technology, which has now become a key to our survival.

  • http://reserveenergy.blogspot.com/ Corey Barcus

    Concerning weapons proliferation:

    I believe this is a complete non-issue for energy development because it is the lack of sufficient energy which is a primary driver for the desire for nuclear weapons. Any modern industrial power has the energy necessary for nuclear materials production. If we solve the energy crisis, it will become far easier for us to create these things, provided we are motivated to do it- which should be a significantly smaller problem with energy security.

    LFTR can be designed to be “resistant” to proliferation, but it cannot be made in such a way as to make it impossible. Our hope, which is very well founded scientifically, that by providing adequate energy for civil security, the risk of war (let alone nuclear) will be greatly reduced.

  • Rolf Westgard

    Nuclear plants do not provide weapons grade nuclear fuel. Our 104 nuclear plants are the safest industry in the US. Nuclear is also very low cost power, especially compared to renewables. And the spent fuel storage is difficult but manageable. Nuclear ignorance is rampant among bloggers and legislators.

  • http://www.facebook.com/people/Colin-Megson/100001496541664 Colin Megson

    Jonathan Mariano writes: “Good news, for the first time, renewable energy usage surpasses nuclear energy”. This article argues that LFTRs are an interim solution. Overall it seems you think renewables can do the trick, providing “we learn to curb our consumption”. Wishful thinking on both counts: it’s impossible for affordable renewables to supply future energy needs at the rate of developing world progress; airheads driving SUVs will still be airheads when SUVs are finally banned.

    LFTRs are unique reactors that can safely and cheaply supply all of the energy needs (including carbon-neutral liquid fuels, nitrate fertilisers and potable water) for everybody on the planet forever.

    • http://www.facebook.com/people/Colin-Megson/100001496541664 Colin Megson

      I Blog on “LFTRs to Power the Planet”: http://lftrsuk.blogspot.com/

      Please join me in the battle to preomote LFTRs.

    • http://www.triplepundit.com/author/bob-siegel/ RP Siegel

      Forever is a long time. So is 20-50 years these days, plenty of time to develop newer and safer alternatives without any radioactive storage requirements or consumable fuels. As far as curbing our consumption goes, if we don’t, then it’s only a matter of time before we run out of something we can’t replace. I’ll stick with LFTR as a possible interim solution, thank you very much.

      • http://www.facebook.com/people/Colin-Megson/100001496541664 Colin Megson

        It’s not just me who thinks ‘forever’! Alvin Weinberg, inventor and patent holder of LWRs thought so too. The Enrico Fermi Award is an award honoring scientists of international stature for their lifetime achievement in the development, use, or production of energy. 1980 – Alvin M. Weinberg.

        Truly, Alvin Weinberg was a doyen of the nuclear power world and the work done on Molten Salt Reactors (MSRs) at Oak Ridge National Laboratory (ORNL) was done under his Directorship in the 50s, 60s and 70s. In his autobiography, Weinberg opined: “I became obsessed with the idea that humankind’s whole future depended on the breeder. For Society generally to achieve and maintain a standard of living of today’s developed countries depends on the availability of relatively cheap, inexhaustible sources of energy.”

        By ‘Breeder’, Weinberg meant the breeding of fertile Th230 fuel to the fissile U233 energy source, in an MSR (now known as LFTR). U233 transmuted from Th230 is the inexhaustibly availabile thorium.

        Only price will curb our consumption; under any price conditions the airheaded attitude towards energy, of the public at large, will ensure energy demand is always ‘maxed out’. Forget voluntary curbs; forget political curbs – curbs and votes will never be bedfellows.

  • Ronald


    Excellent discussion and comments.

    For Further information on LFTR see

    Energy From Thorium

    Nuclear Green Revolution

    Thorium Remix Youtube Video

    I do agree that the implementing the LFTR Technology will not be Carbon Free.

    If you and your readers were to read the Nuclear Green Revolution blog you will see that

    Solar, Wind, Ethanol and other Bio-fuels are Material and Energy intensive to develop and exploit. The Concrete and Steel needed to produce each Megawatt of Electric Power for Wind power compared to Gas Turbine or Proposed LFTR is staggering.

    The Intensity of Carbon Produced in Steel and Concrete manufacture is quite high.

    The Advantages of Nuclear Green LFTR is the High Energy Density in the Fuel and it’s use. A Gigawatt sized LFTR has a tiny land footprint compared the land required for the same amount of power of the former. Gigawatt LFTRs would easily fit in the Parking Lots of any Coal Plant.
    Small 200 MW LFTRs can be placed near the cities and towns they serve doing away with High Voltage InterState Power Lines.

    The Jevons Paradox shows that efficiency will not lower the consumption of energy.
    Cheaper Fuel and Higher Gas Mileage for cars encourage more driving. More efficient Air Conditioning/Furnace encourages a lower/higher Thermostat setting.


    The Beauty of LFTR is it’s ability to Supplant Dirty Coal and bring Electrical Power and Industrial Process Heat to all the Developing Countries to aid in their economic development. China, India and New Industrialized Countries such as Brazil and Turkey will not wait, but will continue develop their Energy and Transportation infrastructures.

    Another way of stating the problem. The Wind and Sun are free. The Sun doesn’t always shine and the Wind doesn’t always blow. Wind and Sun cost a lot of money and material to exploit it for energy. Thorium is abundant and when exploited in a LFTR is relatively “Carbon Free” in construction and operation.