Can Nuclear Power be Green ?

Can Nuclear Power really be Green?
Patrick Arnesen, Vancouver BC, July 2009

Environmentalists dismiss Nuclear power as a dirty, dangerous and expensive technology that's incompatible with a green future. In fact many organizations such as Greanpeace dismiss it outright as a green power solution. However if you look at their arguments you'll notice that when they use the term "Nuclear Power" they are really referring the technology behind today's conventional fission reactors. I believe that many environmentalists are arguing from ignorance. They are simply not aware of the other available forms of nuclear power such as Liquid Fluoride Thorium Reactors (LFTR), which offer solutions to virtually all of the problems put forward as arguments against nuclear power. This is a terrible shame. By not distinguishing between conventional nuclear technology and other options such as LFTR, environmentalists are campaigning against the very technology that could most readily bring about the green future they long for.

I believe that LFTR offers the greenest available power solution. It's greener than solar and it's greener than wind. Here's why: To properly compare LFTR to wind and solar, you need to look at the full impact of converting our energy industry over from today's oil, coal and natural gas infrastructure to the new technology. You can't just look at a single windmill or a power station and weigh the pros and cons. You have to consider the whole infrastructure you need to build up around it. When you do that, LFTR wins.

Grid Comparison

Lets begin by considering what a mature LFTR and a mature wind/solar power grid would look like. A LFTR based power grid would be a simple affair. Most of the reactors would be in the 50 to 200 MW power output range and could be located close to where power is needed such as towns and factories. LFTRS can increase or decrease power in real time to meet changing demand, so that they can reliably handle peak demand periods. On a hot summer day when thousands of buildings turn on their air conditioners, LFTRS can be counted on to deliver the power.

In contrast wind and solar power suffers from two major logistical obstacles: The power output can't be controlled (it gets dark at night or when it's cloudy, and sometimes the wind dies down), and the best available sources of power are often far from where they're needed. To collect as much power as possible when it's available, and to overcome clouds and calm days, you would need to build many more windmills and solar stations than you would need if they reliably produced their rated output. To deliver power at night when the sun goes down you would need to build massive power storage stations; and to get the power from where it's made to where it's needed, you would need to completely rebuild the world's power-lines at enormous expense. To recap, a solar and wind future is not just about the windmills and solar cells, you need to factor in the environmental costs of power buffering and transportation as well.

Construction Impact

To produce 1GW of power, enough for a small city, you would need to build perhaps 3 to 4GW of wind and solar power, possibly dozens of GWH of storage capacity, and perhaps 500 miles of new power-lines and upgrades. Because of their inherent safety and because they operate at atmospheric pressure, LFTRs do not need massive pressure vessels and containment walls like conventional reactors do. Also the because they operate at much higher temperatures, they can drive air turbines, which are far smaller and lighter than steam turbines. Thus a 1GW LFTR would require far less construction material than a conventional reactor. On the other hand the wind and solar option would use at least 4 to 5 times as much material as a LFTR (and probably a lot more).

Every ton of steel or aluminum means digging up hundreds of tons of ore. It must be smelted, purified, alloyed, rolled and transported, all at great environmental cost - and that's just the metal. You'd also need to factor in the impact of concrete, aluminum, copper, carbon fiber, plastic, fiberglass, electronics, assembly... the list goes on. Finally consider that to replace today's dirty power production, increase the world's output enough to electrify our cars, ships, trucks, planes and trains, and meet the demand of billions more people, we'd need to build the equivalent of thousands of 1GW plants!

Operational Impact

For both options the largest costs and environmental impacts are incurred during the construction phase. Once built, both technologies run with relatively little environmental impact. On the operational side I think that it's unclear which technology is more harmful to the environment, but given that the construction impacts are so much higher, the debate on operational impact is reduced to insignificance. To justify this point of view, I'll quickly summarize the operational impacts of both options.

With solar power we'll need to dedicate millions of hectares of land from what could otherwise serve as natural areas. There could also be some environmental cost to the massive buffering stations if they need to boil water to make steam.

Putting up enough wind power to run the world could have an impact on birds. These impacts may be somewhat lessened by carefully studying their migratory patterns and building windmills where birds are less likely to fly into them, but this may have the adverse affect of forcing us to avoid the most ideal sites. We would then need to build even more windmills and bear the impact of their construction to make up for the shortfall.

Like wind and solar, LFTRs don't consume any water to make steam, and they don't produce any emissions. Their environmental impact would mostly stem from mining thorium. However the amount of mining needed is surprisingly small. A 1GW city sized reactor LFTR would only need about 1 ton of fuel per year, extracted from about 200 tons of ore (this is a completely trivial amount next to the hundreds of thousands of tons of ore needed by traditional nuclear reactors, and the millions of tons of ore needed to fuel a 1GW coal plant for a year).

The environmental impact of the nuclear waste produced by a LFTR reactor should be zero. The waste would never be released into the biosphere and would be so minimal that it could easily be dealt with safely. Because it's so efficient, 1GW LFTR would only produce about 1 ton of radioactive waste per year. The reactor would produce virtually none of the dangerous transuranic waste produced by conventional reactors, and which lasts for thousands of years. Instead, transuranics remain in the reactor core and are themselves consumed as fuel (hence the high efficiency). What's left are much lighter fission products. Most of them lose their radioactivity within the first 10 years of storage and could then be safely recycled. The remaining waste (less than 1/3 ton) would remain radioactive for less than 500 years. It could be safely encased in glass and stored in secure locations until they cool down to safe levels. Thus the amounts of radioactive waste produced during operation, and the mining needed for fuel is tiny - 6 rail cars of fuel would be more than enough to power all of North America for a year! As an added bonus, LFTRs can also burn much of the radioactive waste that has already been produced by contemporary reactors.

At the end of its lifetime, a LFTR reactor would need to be decommissioned. This would again incur an environmental cost. The reactor core (radioactive from decades of neutron bombardment) would need to be safely allowed to cool for a few decades, and all the construction materials recycled. However windmills and solar plants and power storage stations also have limited lifespans and would need decommissioning.

Conclusion

Both LFTR and Wind/Solar power incur the vast majority of their environmental costs during their construction phases. Given that LFTRs require far less construction material, labor and land to build and deploy, their overall environmental impact should be much smaller. LFTR would not only be the cheapest and most dependable energy source available, it would also be the greenest.