Is nuclear renewable? Does it matter?

Renewable or not, here I come: Image courtesy Wikimedia Commons

Human use of fossil fuels is changing the climate of our planet. Fossil fuels are running out, but not fast enough. Long before oil and natural gas reserves are exhausted, climate change will be catastrophic and irreversible. We cannot rely on the law of supply and demand to price fossil fuels out of the market. We need to take decisive action, and we need to take it now.

As the sense of impending doom becomes stronger, and more and more people cry out for a solution, one voice has been coming through loud and clear. Advocates for nuclear energy are putting their technology forward as the answer to the climate change problem. When energy is produced from fission, no carbon dioxide is emitted, say the nuclear promoters. It is a proven technology with a half-century track record. Why grasp around frantically at wind, solar, and biomass when we already have the answer at our fingertips?

Often, this leads to a philosophical debate. Is nuclear energy renewable? Opponents say it is not. They base their argument on one key point: To be renewable, an energy source must not require continual addition of any fuel.

Wind, solar, hydroelectric, tidal, biomass, and geothermal energy sources do not require fuel. Virtually all of them are ultimately derived from the sun. The cause-effect relationship is obvious in the case of solar photovoltaic arrays, solar concentrators, and solar thermal systems.

In the case of wind, hydroelectric, and biomass, the relationship is indirect. The sun heats the earth, the earth releases this heat into the air, the heated air column rises, cooler air rushes in to replace it, and the energy of that moving air is harvested with wind turbines. The sun warms water bodies and causes evaporation, the water vapour moves to cooler areas and condenses into rain, the rainfall fills rivers, and the flowing river water turns hydroelectric turbines. The sun shines on plants, the plants use photosynthesis to convert the solar energy into sugars, and man-made chemical processes convert the sugars into biofuels. As long as the sun continues to shine, these energy sources will be inexhaustible.

Tidal and geothermal are a bit different, but are similarly inexhaustible. As long as the earth continues to revolve around the sun, and the moon around the earth, there will be tides, and tidal energy that can be harvested through a variety of means. As long as the radionuclides in the Earth’s crust continue to decay, there will be geothermal energy.

By contrast, nuclear energy, at least that supplied by conventional reactors, requires fuel – uranium, plutonium, or thorium. As the plant runs, the fuel is consumed. The spent fuel is unusable and must be stored indefinitely (unless more exotic means to extract additional energy from the fuel are available, such as reprocessing or fast breeder reactors).

So, philosophically at least, it is not possible to argue that nuclear energy is renewable. It isn’t. But that is answering the wrong question. Renewable or not, is it desirable? In other words, our current energy infrastructure is in crisis. We cannot simply stop using it, without causing a global economic collapse. But if we continue to use it as-is, we risk a global economic collapse. So the real question is, can nuclear energy lift us out of this Catch-22?

This is a three-part question. First, does nuclear solve the climate change problem? Second, is it sustainable, at least over a viable time frame? Third, does it create more problems than it solves?

The first question appears simple. A nuclear power plant produces electricity, waste heat, and spent fuel, but no CO₂. That looks like a promising solution. However, the start and end of the reactor lifetime and the fuel life cycle are not nearly as innocuous. The plant must be built, and nuclear plants require a great deal of concrete. Manufacturing the cement in that concrete produces a lot of carbon dioxide – globally about 5% of CO₂ emissions come from cement manufacturing, either directly from calcination of limestone or from the fuel that is burned in the kiln. Then there’s the emissions arising from manufacturing and transporting all the steel reinforcing bars, building and operating all the heavy construction vehicles, producing and shipping all the exotic materials used in the reactor itself, not to mention mining, milling, refining, enriching, forming, and ultimately storing the uranium fuel, and storing the low-level waste after plant decommissioning.

According to National University of Singapore research fellow Benjamin K. Sovacool, it all adds up to about 66 grams of CO₂ equivalent per kilowatt-hour. That’s a huge improvement over coal-fired power generation, which produces 14 times the amount of greenhouse gases. However, that’s twice the carbon footprint of solar photovoltaic power, and six times as much as land-based wind power. From a carbon footprint perspective, nuclear does not have an advantage over the leading renewable energy technologies.

What about sustainability? The International Atomic Energy Agency estimates that proven uranium reserves are enough to supply current levels of demand for 85 years. If nuclear proponents are successful, nuclear power usage would expand significantly above its current level of 6% of global energy supply, reducing the lifetime of uranium stocks. However, an increase in uranium demand would lead to greater exploration efforts, likely extending reserves significantly. In any case, technologies like fast breeder reactors could make the supply last up to 2,500 years. That’s a lot less than the 5 billion years that the sun is expected to continue to shine, but for practical purposes, the availability of fuel does not represent a real constraint.

Finally, there is the question of whether the cure is worse than the disease. Nuclear disasters such as Fukushima have produced significant fears in the minds of the public. The difficulty is that the harm caused by nuclear disasters is front-page news. By contrast, fossil fuel usage causes ongoing damage to property and public health which is much more significant, and grossly under-reported. By virtually any health, safety, or environmental measure – including worldwide release of radioactive materials – nuclear power is a significant improvement over fossil fuels.

However, we’ve already established that fossil fuels need to go. We’re not making a choice between them and nuclear. The choice is between nuclear and renewable energy technologies in the strictest sense. There is little or no credible, peer-reviewed evidence of negative health impacts from wind turbines – although the industry needs to make a dramatic change to the way it engages with communities, to avoid breeding the discontent that provides a fertile field for the anti-wind lobby. End-of-life solar panels may suffer the same environmental problems as obsolete consumer electronics like cell phones and MP3 players, but the problem is hardly immediate given that they last more than 20 years. Other renewable technologies are similarly benign.

The Achilles heel of nuclear is waste. A recent newsletter from the Ontario Clean Air Alliance had the eye-catching subject line, “You don’t build a house without a toilet”. That is precisely what the nuclear industry has done. Globally it produces 10,000 m³ of high-level radioactive waste per annum; this remains deadly for tens of thousands of years. As yet there is no solution to this problem. Until that changes, the nuclear sector will continue to have one shortcoming that outweighs all of its advantages.

In summary, nuclear energy has a significantly smaller carbon footprint than fossil fuels, but still much higher than wind and solar. There is enough fuel on the planet to keep the reactors going for a very long time. However, in that time those reactors will produce a vast amount of deadly waste.

If the nuclear industry can reduce its carbon intensity across the entire life cycle of the fuel and the reactors, and if it can solve the waste problem, it will indeed be a solution.

It will also be a miracle.