With the coronavirus pandemic raging and the economic devastation it has wrought - not to mention all the other social turmoil this year has seen - it can be hard to focus on anything else. But climate change is still with us, and strong efforts are still needed to prevent the worst effects it can still bring in the short, medium, and long terms.
Current sources of renewable energy such as wind and solar have major drawbacks. These forms of energy are either intermittent (unpredictable), have low levels of energy density, or both. This means they need either huge swaths of land, huge batteries, or both. Also, huge amounts of natural resources will need to be mined and manufactured, and several technological breakthroughs in battery technology will need to be made, before we can power our society with it. The amount of electricity consumed by humanity is truly enormous: 25,606 TW-hrs, as of 2017. Since the twenty first century, global electricity consumption has increased annually by 3.4%, with developing countries increasing their electricity demand rapidly.
To limit climate change to acceptable levels, a large portion - if not all - of the global electricity supply will need to come from carbon-free sources. Currently, the United States produces about 1 pound of CO2 per kilowatt-hour of electricity; values for developing countries, which tend to rely ore heavily on coal and natural gas, are likely higher. Fossil-fuel-related carbon dioxide emissions hit a record high of 37.1 billion metric tons in 2018. Drops caused by the COVID-19 lockdowns were significant, but too expensive to sustain, and still too small to bring emissions levels to acceptable levels.
To have a chance of limiting temperature increases to below 3.5 degrees Fahrenheit (2 degrees Celsius), any climate scientists view nuclear energy as a crucial source of power. Per Forbes, “nearly all mainstream projections of the world’s path to keeping the temperature increase below those levels feature nuclear energy in a prominent role.” And according to the IEA, “achieving the clean energy transition with less nuclear power is possible but would require an extraordinary effort,” an effort which the world does not currently show the political will or unity to make happen. A new form of nuclear energy called Traveling Wave Reactor (TWR) technology shows promise. If it is adopted widely enough, it may produce significant amounts of carbon-free energy for the benefit of the planet and its people.
A Brief Explanation of Nuclear Energy
Some atoms are so large as to be unstable. Occasionally these unstable atoms will split themselves spontaneously. When this happens, it splits into two smaller atoms, and some neutrons. Also, some of the mass of the original atom turns into energy (remember that Einstein taught us that a small amount of mass can become a large amount of energy, and vice versa). Some of the neutrons that went flying off will collide with other atoms, which immediately causes them to decay as well. If you get enough fissile atoms packed in close proximity to each other, they can create a continual chain reaction, causing them to produce large amounts of energy. This process is called “fission,” and atoms that can undergo fission are called “fissile.”
The amount of electricity that can be produced by the fission reaction is truly enormous. Nuclear power plants currently in operation range anywhere from 510 MW to 1,500 MW. The United States generates 98 GW of nameplate capacity. That corresponds to up to 807 TW-hrs total of nuclear power every year, which is more than any other country, and accounts for 20% of the nation’s electricity.
Splitting atoms can be tricky, however, and the fission process creates a witch’s brew of radioactive byproducts. These byproducts emit harmful gamma rays for decades, centuries, millennia, or longer. They have to be carefully controlled, gathered, and stored indefinitely until future generations can figure out what to do with them. Also, high-level waste has to be guarded carefully: it can often be turned into fissile material, which can power a nuclear bomb in the hands of a rogue actor. Lastly, the methods to prevent nuclear meltdowns are comparatively primitive and are not fail-safe: if things go wrong, power plants can essentially become small bombs, blowing their top and releasing radioactive byproducts into the environment. This has happened occasionally, and the resulting outcry has largely soured the public on nuclear energy. Plus, the cost to build next-generation plants to current safety standards is enormous. Enormous cost overruns and schedule delays have scuttled or threatened several next-generation nuclear plants in the United States in recent decades.
Which is a shame, because the amount of energy that nuclear power can produce would be tremendous, certainly enough to power society’s needs for the foreseeable future. And - crucially - it wouldn’t emit any carbon dioxide. If society could produce nuclear power that is safe, waste-free, scaleable, and cheap, humankind’s energy needs could be met, essentially forever. That’s still a big ask, but emerging technologies may be up to the task.
The Traveling Wave Reactor
In 1995, Edward Teller and Lowell Wood, two veterans of the American nuclear scene, published a paper outlining a new type of nuclear energy. The new system - called the “Traveling Wave Reactor”, or TWR, works in a manner very different from standard nuclear reactors. Most nuclear reactors run on a very highly enriched fuel: the atoms needed to run a nuclear reaction don’t naturally come in very high concentrations, so you need to pre-process it to get the right atoms in high concentrations. TWR, in contrast, runs off of a low-concentration material, which can enrich itself in a progressing, traveling wave. The extra neutrons that are flying around are used to turn useless fission byproducts into useful fissile material, which are then reacted as fuel.
In a TWR reactor, many disadvantages of traditional reactors are lessened or prevented entirely. First, the radioactive elements created are of the sort that need to be stored for decades, not forever. Second, existing spent fuel (which is currently stored indefinitely in special dumps) can actually be used to power the TWR. Third, there are no concerns about the byproducts being stolen and used to make bombs. Fourth, the way the reaction is controlled is inherently passive, so there’s no way for the plant to blow its top and release radioactive material. If the power turns off, it just stops.Â
If TWR succeeds, the dream of nuclear power - limitless clean power for mankind’s benefit - could one day be realized. Just the power attainable from one nuclear waste storage site in Paducah, Kentucky could power the United States’ current energy needs for 100 years. All while burning up much of our existing nuclear waste.
This technology has been noticed and backed by none other than Bill Gates. He is working, through his foundation, to bring a TWR reactor to life. He has invested heavily into a technology incubator startup called TerraPower. Since 2007, TerraPower has been refining the process and design of their plant. Earlier this year, TerraPower announced a partnership with GE Hitachi to design and build a reactor plant design called Natrium. Natrium would pair TWR technology with molten-salt energy storage systems. The heat generated by the 345 MW reactors could be stored in the molten-salt tanks, and converted into grid electricity to smooth out fluctuations from other renewable energy sources.
Hurdles to the TWR
Several hurdles exist to building a TWR reactor, let alone to powering the public grid on them. The first is public acceptance of nuclear power. After the nuclear disasters of 3 Mile Island, Chernobyl, and Fukushima, the public is simply frightened of new nuclear plants. Ever-more stringent regulations for building, operating, and decommissioning nuclear power have driven up construction and operating costs, at a time when all other renewable energy costs are falling quickly. A “Not In My Backyard” mentality has also hindered efforts to construct new nuclear in the United States. TerraPower actually tried to build their prototype plant in China when public pressure and regulations made it too difficult to construct in the US. Their plans for a Chinese nuclear power plant were scuttled by the Trump administration, however, when they canceled the permissions needed to transfer the technology overseas.
An additional hurdle is the unknown nature of a first-generation TWR plant: it is very difficult - if not impossible - to know how much these plants will cost until one is built. Current next-generation nuclear plants have been plagued by cost overruns and delayed schedules due to unforeseen issues in plant construction, design, and startup. TerraPower estimates the cost of a 345 MW Natrium plant at $1 billion - though until a few are built, that will always just be an estimate. Recently, TerraPower won an $80 million grant from the Department of Energy to further develop the Natrium design. No publicly available information is available on TerraPower’s current operating budgets, but the overall expense of developing and deploying the technology is certainly in the billions or tens of billions of dollars. At one point last year, Gates offered to personally invest $1 billion - and raise $1 billion in private capital from other sources - if Congress would commit to supporting it.
The last question is whether the technology will be ready to deploy at scale in time to help combat global warming in a real way. Several scientist groups have published reports critical of the technology, including one from MIT in 2018. They contend that the technology remains more theoretical than proven, and that significant advances in fuel and materials technology will be needed to make it work. Given the urgency of addressing climate change, and the limited nature of capital to deploy to fight it, there are real questions about if it makes sense to fund moonshot projects like the TWR, or to use the capital to deploy ever-more wind, solar, and batteries.
Conclusion
As long as it overcomes the hurdles to its development, financing, construction, and deployment - which is by no means certain at this point - the Traveling Wave Reactor technology shows great promise as a next-generation nuclear technology. It offers the promises of carbon-free energy at large scale, very high levels of safety, and the burning of existing nuclear waste into energy and harmless residue. If it can be brought to fruition at a large scale in a short time, it should be something we can get behind. If not, it may make more sense to put public resources into deploying proven technologies at a larger scale.