Last year, Kirk Dorius and I travelled to London to participate in the kickoff of the Weinberg Foundation, an advocacy group for thorium energy. I am pleased to announce with them the formation of an “All-Party Parliamentary Group” or APPG that contains members of both the House of Commons and House of Lords, to consider the potential of thorium as an energy source.
In a word, “Duh.”
Here’s the thing folks, when you boil it all down — thorium is a no-brainer when it comes to a nuclear fuel and fuel cycle, assuming you want power and not bombs. It also is the enabling pathway to petroleum independence without changing the consuming end of the pipeline.
Many “green” evangelists are all ga-ga over electric cars. But they forget that while chargers are quite efficient (~80-85%) and electric motors are too (~85% for the best of what we can offer today) the fact remains that batteries have a crap energy density (meaning the amount of energy the contain per unit of both mass and volume is poor), they have a poor energy acceptance rate (how quickly you can charge said battery, requiring hours .vs. minutes to fill a fuel tank) and in addition they simply shift where the energy production takes place (to the coal plant behind the undesirable neighbor’s house.) In other words they simply move the exhaust pipe instead of getting rid of it.
Indeed when you stack the inefficiencies electric cars don’t look so good. A typical gasoline or diesel car is somewhere around 30% efficient end-to-end (that is, the number of BTUs of energy that go into the fuel tank .vs. the amount of energy that actually moves the car.) The rest is lost as heat in some form or fashion, whether out the tailpipe, rejected by the radiator or as friction somewhere in the middle.
But neither do electric cars. When we stack efficiencies we see the problem quite quickly:
30% (conventional nuclear or coal) to 50% (combined-cycle such as natural gas) at origin. 90% efficiency in transmission (transformers, loss on the electrical line, etc) 85% efficient (battery charger) 80% efficient (battery itself, assuming 50% charge state — much less at 85%+ of full charge, perhaps as little as 50%) 85% motor, controller and gearing (in the car) ===== 15.6 – 26% end-to-end
Oops; that’s no better and if you start with 30% gross at the generating end it’s actually worse!
So the argument for “energy efficiency” doesn’t work in favor of electric.
Why does this mean we should use thorium?
Simple — thorium reactors can be run not on pellets of fuel as conventional reactors using water as both a moderator and coolant, but rather with the fuel dispersed in a molten salt used as the working fluid and a fixed moderator in the reactor chamber.
This is a huge win for a number of reasons:
- The reactor runs at much higher temperatures. Typical operating temperatures are in the 550-650 Celsius range as opposed to water-cooled reactors which are limited by the critical point (374 Celsius); beyond that temperature irrespective of pressure water does not remain liquid. This means that the heat of vaporization is zero, which in turn limits the useful working temperature of the coolant. The other problem with water is that to approach the critical temperature requires containment at extraordinary pressures; 217 atmospheres to be exact (over 3,100 psi!)
- LFTR reactors run at normal atmospheric pressure. A big part of the danger with conventional reactors comes from the properties of water at high temperature. In order to keep it liquid you must hold it under extraordinary pressure. Everything is much more difficult from an engineering perspective and any failure of that pressurized state is catastrophic as the water instantly flash-boils to all steam, resulting in the reactor having no coolant! This is also why a conventional reactor requires uninterrupted power all the time; you cannot allow the coolant temperature to go over the critical point and since the fuel produces decay heat after shutdown you therefore must provide continual coolant flow until that heat is extracted. The failure of that continual flow is what led to the Fukushima disaster. LFTRs do not suffer from this problem as they do not operate under high pressure. If all power is lost at a LFTR plant the coolant containing the fuel can be allowed to drain by gravity into tanks where, with no moderator present, the reaction stops and it simply cools over time on its own. This passive safety was tested and proved effective in the United States in the test plant operated at Oak Ridge some 40+ years ago!
- You can use the higher process heat level, up to 650C, to directly convert any carbon source to liquid hydrocarbons. Coal happens to be a convenient source of both thorium and carbon, but in point of fact carbon can come from any source — including atmospheric CO2. The Germans figured out how to turn coal into liquid synfuel during WWII and we have refined that process since then.
- Reprocessing is continuous and online in form; the reaction products are thus nearly all consumed over time, producing a waste footprint that is a tiny fraction of conventional nuclear plants. Conventional uranium-fuel-cycle reactors only have ~5% of the fuel material in the reactor that is actually fissile; the rest is bombarded over time. Some turns into plutonium that can then be reprocessed and burned up, but a large amount of the remainder winds up as highly-radioactive byproducts that are dangerous for enormous lengths of time. A commercial LFTR would be built with “online” reprocessing to separate out the neutron poisons (specifically Xenon) and introduce more thorium as the fuel is consumed. The result is that most of the reaction byproducts remain in the reactor until they are reduced to less hazardous (or non-hazardous) elements and compounds; the decay heat released in this process also is harvested to produce useful energy instead of being dispersed in big cooling pools.
This is not necessarily a “cheap” oil replacement, but “cheap” is relative. Can we produce $20/bbl equivalent oil products with this technology? No. Can we match $100/bbl oil? Probably, and that’s the point — we can both produce electricity and 100% independent liquid hydrocarbons to fuel our buses, trucks and cars.
In addition we would be using a far safer technology than we use today for nuclear power.
I highlighted this alternative in Leverage for a specific reason — behind every unit of GDP is a unit of energy. If we are to ever rationalize our federal government spending on all things, including most-particularly our military, we must become energy independent.
We proved that these reactors can work in the 1950s and 60s at Oak Ridge. This is not “pie in the sky” technology or the subject of science fiction. It is a matter of science fact that we can, if we’re willing, exploit to resolve our domestic energy requirements.
It appears that Britain is going to join China and India in heading down this road, leaving America behind.
We cannot afford to be left behind.