Energy cheaper than from coal

Births vs income

When economic well-being measured by the gross domestic product exceeds a threshold, birthrate drops sharply.

Global warming now threatens irreversible climate damage, ending glacial water flows needed to sustain food production for hundreds of millions of people, and shrinking the polar cold water regions of the ocean where algae start the ocean food chain. Atmospheric CO2 dissolving into the ocean acidifies it, killing corals and stressing ocean life. Demand for biofuels increases destruction of CO2 absorbing forests and jungles.

Burning coal for power is the largest source of atmospheric CO2, which drives global warming. Airborne coal soot causes 24,000 annual deaths in the US and 400,000 in China. We seek alternatives such as burying CO2, or substituting wind, solar, and nuclear power.

The world population growing from 6.7 to 9 billion will increase resource competition, exacerbating environment stress. Yet the OECD nations, with adequate energy supplies, have birthrates lower than needed for population replacement. Nations with GDP per capita over $7,500 have sustainable birthrates. Electricity for water, sanitation, lighting, cooking, refrigeration, communications, health care, and industry contributes to economic development. Those nations with per capita electricity of 2,000 kWh/year (1/6 US use and an average power of 230 W) do achieve GDP of $7,500 per capita, which leads to sustainable birthrates.

Taxing carbon seeks to encourage energy sources that do not emit CO2, yet this has not been effective in Europe. Developing countries will not agree to carbon taxes and forgo an advantage they perceive led to prosperity in OECD nations. Alternatively, a source of energy cheaper than from coal would dissuade all nations from burning coal, without imposing tariffs or taxes that reduce economic productivity. Affordable electric power can also help developing nations reach modest levels of prosperity and lifestyles that include sustainable birthrates.

The objective for energy cheaper than from coal is $0.03/kWh and a capital cost of $2/watt of generating capacity. How can the liquid fluoride thorium reactor produce energy cheaper than from coal?

Fuel costs. Thorium fuel is plentiful and inexpensive; one ton worth $300,000 can power a 1,000 megawatt LFTR for a year – enough power for a city. Just 500 tons would supply all US electric energy for a year. The US government has 3,752 tons stored in the desert. US Geological Survey estimates reserves of 300,000 tons, and Thorium Energy claims 1.8 million tons of ore on 1,400 acres of Lemhi Pass, Idaho. Fuel costs for thorium would be $0.00004/kWh, compared to coal at $0.03/kWh.

Capital costs. The 2009 update of MIT’s Future of Nuclear Power shows new coal plants cost $2.30/watt and PWR nuclear plants cost of $4.00/watt. The median of five cost studies of molten salt reactors from 1962 to 2002 is $1.98/watt, in 2009 dollars. The following are fundamental reasons that LFTR plants will be less costly than coal or PWR plants.

Pressure. The LFTR operates at atmospheric pressure, without a massive reactor vessel pressurized to 160 atmospheres, and without a large containment dome needed to contain any accidentally released radioactive materials propelled by pressurized steam. One concept for the smaller LFTR containment structure is a concrete building below grade, with a concrete cap at grade level to resist aircraft impact.

Safety. PWRs are safe because of defense in depth – multiple, independent, redundant systems engineered to control faults. LFTR’s intrinsic safety keeps such costs low. A molten salt reactor can’t melt down because the core is already molten — its normal operating state. The salts are solid at room temperature, so if a reactor vessel, pump, or pipe ruptured the salts would spill out and solidify. There is no explosion potential because the pressure in the reactor is atmospheric. If the temperature of the salt rises too high, a solid plug of salt in a drain pipe melts and the fuel drains to a dump tank; the Oak Ridge researchers turned the reactor off this way on weekends.

Heat. The LFTR safely operates at high temperatures. Salt remains liquid below 1400°C; internal graphite core structures maintain integrity even above this. Molten salt heat capacity exceeds that of the water in PWRs or liquid sodium in LMFBRs, allowing more compact heat transfer loops. The molten salt heat exchange loop components of high-nickel metals such as Hastelloy-N are qualified up to 750°C.

Helium gas (green) is successively heated by 700°C molten salt (red) from a LFTR heat exchanger as it passes through high, medium, and low pressure turbines (T). The gas cycles back through three successive compressors (C), cooled by fluid (blue) that transfers rejected heat externally. The recuperator (R) transfers some energy from the compression cycle back to the expansion cycle. The generators (G) produce electricity. (Diagram courtesy of Per Peterson of UC Berkeley.)

Brayton Cycle. The triple reheat closed cycle Brayton turbine achieves a 45% efficiency of conversion from thermal to electric power, compared to 33% typical of existing nuclear and coal power plants using traditional Rankine steam cycles. The Brayton rejected heat to power ratio is thus 1.2 (55/45) rather than Rankine’s 2.0 (67/33) so the cooling requirements are nearly halved, reducing cooling tower costs and making air cooled LFTRs practical in arid regions where water is scarce. This compact Brayton turbine machinery is a quarter the mass, suggesting a similar cost reduction.

Boeing, producing one $200 million airplane per day, is a model for LFTR production.

Mass production. Commercialization of technology leads to lower costs as the number of units increase. Experience benefits arise from work specialization, new processes, product standardization, new technologies, and product redesign. Business economists observe that doubling the number of units produced reduces cost by a percentage termed the learning ratio, seen in the early aircraft industry to be 20%. Today Moore’s law in the computer industry illustrates a learning ratio of 50%. In The Economic Future of Nuclear Power University of Chicago economists estimate the learning ratio is 10% for nuclear power reactors. Boeing, producing one $200 million airplane per day, is a model for LFTR production. Reactors of 100 MW size costing $200 million can be factory produced. Manufacturing more, smaller reactors traverses the learning curve more rapidly. Producing one per day for 3 years creates 1095 production experiences, reducing costs 65%

Research. Cost reductions are presaged by current engineering research. Compact, thin-plate heat exchangers may reduce fluid inventories, size, and cost. Possible new materials include silicon impregnated carbon fiber with chemical vapor infiltrated carbon surfaces and higher temperature nickel alloys. Operating at 950°C can increase thermal/electrical conversion efficiency beyond 50%, and also improve water dissociation to create hydrogen for manufacture of synthetic fuels such as methanol or dimethyl ether that can substitute for gasoline or diesel oil, another use for LFTR technology.

In summary, LFTR capital cost targets of $2/watt are supported by simple fluid fuel handling, high thermal capacity heat exchange fluids, smaller components, low pressure core, high temperature Brayton gas turbine power conversion, simple intrinsic safety, factory production, the learning curve, and new technologies already under development. A levelized $2/watt capital cost contributes $0.02/kWh to the power cost. With plentiful, inexpensive thorium fuel, LFTR can generate electricity at <$0.03/kWh, underselling power generated by burning coal. Producing one LFTR of 100 MW size per day could phase out all coal burning power plants worldwide in 38 years, ending 10 billion tons of CO2 emissions from coal plants now supplying 1,400 GW of electric power. Low LFTR costs are vital to this coal replacement strategy, achievable if this goal is maintained during every design choice. Inexpensive electric power can also assist developing economies to improve prosperity, encouraging lifestyles with sustainable birthrates.



17 Replies to "Energy cheaper than from coal"

  • David Archibald
    July 11, 2010 (5:10 pm)

    Kirk, love your work, but there is no need to demonise carbon. The oil price rise we will see over the next few years will make coal too valuable to burn in power plants. At US$120/bbl, it will be worthwhile to close coal-fired power plants to free the coal for coal-to-liquids, with the coal generation replaced by nuclear. If you email me your postal address, I will send you a book on climate I just published.

  • IceTrey
    July 11, 2010 (10:05 pm)

    Huh? You just read a whole article about how LFTR is better than PWR. Why replace coal with conventional nuclear? This entire site is dedicated to replacing both.

  • Alex P.
    July 12, 2010 (6:28 am)

    Mr. Hargraves,
    have you got a favourite LFTR configuration ? For example, a moderator free, epithermal LFTR brreder is more compact than a graphite moderated version, avoiding the need of the graphite and allow to produce it in factory, and not on site installation, at power size in the range of 300-400 MWe against only 100 MWe as you proposed

    Second, if we are successfull to operate the reactor with an outlet temp > 700 °C, I think that even with supercritical steam cycle we can aproach efficiencies of 45-50 %

  • Robert Hargraves
    July 12, 2010 (7:54 am)

    Alex P,
    The favored configuration operates with thermal neutrons, allowing a smaller fissile inventory. Smaller, 100 MW reactors permit smaller at-risk investments by utilities; this is the reason for new products by NuScale, Hyperion, B&W, and others.

  • Al Fin
    July 12, 2010 (2:19 pm)

    As long as government holds the noose / collar over the necks of energy developers, energy entrepreneurs will have to go begging to government bureaucrats for a moment of their precious time.

    David, Mr. Hargraves has to speak in the language of carbon hysteria whether he believes it or not, because that is the language which the regime in power understands. Unfortunately, the regime is solidly behind big wind and big solar, which leaves society with very little real energy to work with.

  • Alex P.
    July 13, 2010 (6:13 am)

    Personally, I don' t like the idea a nuclear reactor is too small, I think the optimal size is that of nat gas CC, i.e. in the range of ~400 MWe; however, are you really sure that a graphite moderated 100-200 MWe core is so smaller than an epithermal moderator free 300-400 MWe core ? The fissile start up is not so bigger, as far I remember less than one tonn per GWe vs a few tonnes at max per GWe – a LWR, in contrast, needs about 5 tonns of fissile uranium – but an epithermal version can be smaller and avoid the use of graphite as final waste

  • Robert Hargraves
    July 13, 2010 (6:53 am)

    The French R&D groups have been studying epithermal. Any size difference will be insignificant compared to the large LWR.

  • Alex P.
    July 13, 2010 (11:42 am)

    Actually, I guessed that Grenoble group choiced a very fast spectrum LFTR (even if not like a sodium fast breeder), I rather prefer an intermediate-energy spectrum solution (epithermal) like the tube on tube suggested by David LeBlanc, where the fissile start-up is no more than a few tonnes per GWe and avoids the use of graphite eventually discharged as waste, but to be honest I don't know all details and drawbacks in terms of feasibility and engineering complexity

  • Alex P.
    July 13, 2010 (5:04 pm)

    However, if we have to follow the graphite moderated reactors route, then I' d prefer to prioritize the quite simple and quick to develop denatured MSR configuration,
    it's not a "real" breeder, only a reactor with a very high conversio ratio, but has anyway pratically all the advantages of a thorium breeder, including a very low transuranic waste production (in the range of only few tens of grams per GWyear)

  • Dave Narby
    July 13, 2010 (9:47 pm)

    Hey what's up with this?

    Thorium imports jumped in 2006, along with the price!

  • DocForesight
    July 14, 2010 (4:54 pm)

    Along the lines of David Archibald, what is the average pH of the oceans now and what does "acidifying" 70% of the earth's surface take?

    Seems to me, climate alarmism is unbecoming of nuclear power advocates. LFTR and all others can stand on their own merits as far superior to any other base-load generator.

  • Robert Hargraves
    July 14, 2010 (8:48 pm)

    Dave Narby,
    The thorium consumption illustrated in your links are very small. Although there is plenty in the US, demand is so low that it's not mined here. Consumption is shown as negative in the last year, evidencing a high noise-to-signal ratio in the data — because the market is so small.

  • Robert Hargraves
    July 14, 2010 (8:53 pm)

    DocForesight and Dave Archibald,

    My postal address is 7 Cuttings Corner, Hanover NH 03755.

    Doc is right in that LFTR power can be justified even without considering global warming. 24,000 deaths/year in the US are due to coal-plant sourced small particulates in the air we breath — hundreds of thousands in China — over a million worldwide.

    Energy cheaper than from coal also has a substantial economic productivity benefit, including advancing developing nations' lifestyles to included lower birthrates, reducing global competition for finite global resources.

  • DocForesight
    July 16, 2010 (4:41 pm)

    Thank you for your response. First, I am not a nuclear physicist – merely involved in the health care field – but have come to recognize the vast superiority of nuclear power to meet the needs of most societies. Your graph gives a visual representation to what many of us understand intuitively.

    From Rod Adams' blog I ran across this site with a number of excellent articles:
    While they don't mention Thorium, they strongly advocate for nuclear power plants to pull the 2+ billion people who don't have basic electricity.

    Keep up the good work, sir.

  • Matt Musson
    July 19, 2010 (8:39 am)

    Most people who are against Nuclear energy have an emmotional arguement against it. Rarely can you overcome emmotions with facts. Ask any guy who fights with his girlfriend.

    That is why I believe Thorium has a better chance of being accepted by the general population. When the tree huggers freak out you can point out that all their objections are against uranium reactors. But, Thorium is different.

    I believe Thorium and Sub-critical uranium reactors have the best chance of being accepted by the public. (And, government regulators.)

  • Scottar
    July 31, 2010 (2:59 pm)

    Global Warming ended in 1998. I'm for any viable energy alternative that is cost effective and cleaner than coal or oil. Nuclear is on that list. It's getting past the scaremongering of the 70's and getting the right engineering, technology and design that is the problem.

    Investing in ENRON technologies like wind and solar farms that are driven more by subsidies then real profits is a crime as well as a scam.

    LFTR sounds even better than the High Temperature Gas Reactors but I don't believe in a cookie cutter approach. A reasonable amount of diversification would be prudent as you just don't know what future breakthroughs will occur, even with renewables.

  • Luciano Miceli
    August 2, 2010 (12:56 am)

    Finally an exciting option for producing energy. The time has come for taking the raps off of Thorium and get the show on the road because the need is there and with the passing of time that need will become more critical. Our energy independence is already at stake, so lets get moving, put pressure on the politicians and educate the general population on how we will benefit by it. For one I do not believe the global warmists, they're wasting huge sums of hard earned money that would be far better spent on getting the ball rolling and start building thorium power plants and increase related research. Thorium will have the last laugh unless we shoot ourselves in the foot and competing economies leave us eating their dust.

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