LFTR Article for "Machine Design"

I was recently invited to write an article for “Machine Design” magazine, and with the help of editor Stephen Mraz, this is what I submitted:

Thorium, a Readily Available and Slightly Radioactive Mineral, Could Provide the World with Safer, Clean Energy

Since I was writing for engineers, I let it get a little more technical, but I hope that people enjoy it.

Comments

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5 Replies to "LFTR Article for "Machine Design""

  • Bryan
    March 17, 2010 (1:53 pm)
    Reply

    A simple calculation to produce a worst-case sustainability estimate*:
    Mr = Estimated mass of available fuel (world)
    Br = Ratio of burnable fuel to total fuel
    Ee = Energy released in one energy-releasing event
    Me = Total mass of one energy-releasing event originating from fuel
    C = Conversion efficiency
    Ec = Power consumed by one individual
    Pe = Projected population of the earth
    T = Time consumption could be sustained

    (Mr * Br * Ee) / (Me * Ec * Pe) = T

    For Thorium:
    Mr = 2,230,000 metric tons
    Br = 1
    Ee = 200.1 MeV
    Me = 234 amu (232-Th + 2n)
    C = 0.5
    Ec = 12,000 kWh / year (1.3 kW)
    Pe = 10 Billion

    T = 226.06 years

    For LWR:
    Mr = 3,338,300 metric tons
    Br = 0.015
    Ee = 202.5 MeV
    Me = 236 amu (235-U + n)
    C = 0.35
    Ec = 12,000 kWh / year (1.3 kW)
    Pe = 10 Billion

    T = 3.54 years

    Crude oil (by comparison, using methane as best-case combustion profile):
    Mr = 1250 billion oil barrels * 0.790 g/cc
    Br = 1
    Ee = 799 kJ / mol
    Me = 16 amu
    C = 0.35
    Ec = 12,000 kWh / year (1.3 kW)
    Pe = 10 Billion

    T = 6.38 years

    * Worst case: 10 billion people consuming at US consumption rates (apx 12MWh/y), and all world's energy produced by cited technology alone.

  • Bryan
    March 17, 2010 (2:02 pm)
    Reply

    Ooh, no sooner than I post that am I corrected! Current average *worldwide* consumption of all energy is ~23MWh/year, or about 2.7W. 1.3 kW was intended to be about double the world average, but is only electrical consumption – only half of all energy consumption, apparently.

    Adjusting figures now. Will also provide T's for stasis population estimates as well.

  • Bryan
    March 17, 2010 (2:30 pm)
    Reply

    A simple calculation to produce a worst-case sustainability estimate*:
    Mr = Estimated mass of available fuel (world)
    Br = Ratio of burnable fuel to total fuel
    Ee = Energy released in one energy-releasing event
    Me = Total mass of one energy-releasing event originating from fuel
    C = Conversion efficiency
    Ec = Power consumed by one individual
    Pe = Projected population of the earth
    T = Time consumption could be sustained

    (C * Mr * Br * Ee) / (Me * Ec * Pe) = T

    Cases (50 year projection):
    Worst case: high population growth with all users consuming current US levels
    Ec = 91 MWh / year (10.381 kW)
    Pe = 11.5 Billion
    Average:
    Ec = 42.5 MWh / year (4.848 kW)
    Pe = 9 Billion
    Best: low population growth with moderate increase in worldwide per capita consumption
    Ec = 32.75 MWh / year (3.736 kW)
    Pe = 7 Billion

    For Thorium:
    Mr = 2,230,000 metric tons
    Br = 1
    Ee = 200.1 MeV
    Me = 234 amu (232-Th + 2n)
    C = 0.5

    T = 43.204 years, 118.2 years, 197.22 years

    For LWR:
    Mr = 3,338,300 metric tons
    Br = 0.015
    Ee = 202.5 MeV
    Me = 236 amu (235-U + n)
    C = 0.35

    T = 0.39 years, 1.05 years, 1.76 years

    Crude oil (as comparison, using methane as best-case combustion profile):
    Mr = 1250 billion oil barrels * 0.790 g/cc
    Br = 1
    Ee = 799 kJ / mol
    Me = 16 amu
    C = 0.35

    (0.35 * (1250 billion oil barrels * 0.790 g/cc) * 1 * 799 kJ amu / g) / (16 amu * 3.736 kW * 7 billion)

    T = 0.72 years, 1.99 years, 3.325 years

  • Geoff
    March 17, 2010 (3:24 pm)
    Reply

    As a manufacturer, I'm intrigued by the possible migration from mega projects like traditional reactors to small distributed units. From a cost standpoint it's recognised that continuous flow has it's advantages versus batch production, (not to mention one-offs).

    I'd be interested to hear more about the anticipated manufacturing challenges of building these reactors.

  • Alex P.
    March 17, 2010 (9:28 pm)
    Reply

    " A LFTR’s gas cooling, on the other hand, rejects heat from about 100°C down to about 30°. In properly built heat exchangers, the waste heat could be used to distill seawater into fresh water "

    Have you ever considered the possibility to slightly increase that reject heat temp to, say, 100-150 °C to produce hot water for district heating/cooling or steam for the production of sustainable (cellulosic ?) ethanol or biofuels (~ half of the total energy input of the final products) ?


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