The Energy From Thorium Foundation » LFTR Article for "Machine Design"

Mar 17, 2010

by Kirk Sorensen

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.

5 Comments

Bryan March 17, 2010 at 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 at 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 at 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 at 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 at 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) ?