A lot of the interest in solar power comes from concern about global warming. Unlike traditional coal or gas-fired power plants, solar power does not create greenhouse gasses that could lead to climate change. But the same can be said for nuclear power plants. So naturally people wonder which is the better choice for a world that wants to rely less on fossil fuels.
Solar and Nuclear are both used to generate electricity, and neither of them generates greenhouse gasses, but after that the similarities end. These are very different technologies with different uses and different risks. There’s no reason we can’t use both to create green power.
This article will look at these two very different methods for generating electricity. I’ll summarize how they work, their strengths and weaknesses, the risks, and the different situations where they work best.
How Nuclear Power Works
Nuclear power starts with radioactive material — usually enriched uranium — that gives off particles as it decays. This is the reactor’s “fuel.” Inside a nuclear reactor, there is enough radioactive material brought together that it starts to react with itself. Atomic particles begin to strike other atoms of uranium, breaking them apart.
The process of decay speeds up, generating heat. That heat is used to generate steam, which powers turbines that turn electrical generators. The enriched uranium fuel is separated by control rods which absorb nuclear particles, keeping the reaction in check. The reactor’s operators can adjust these to control the pace of the nuclear reaction and the amount of heat that the reactor puts out.
This process is similar to how atomic bombs work but at a much lower power level. It is actually very difficult to make radioactive material explode, and nuclear reactors are designed not to. The uranium in nuclear reactors is much less enriched — and less potent — than the material used in weapons.
How Solar Power Works
At the heart of a solar panel are thin wafers of crystal silicon mixed with other chemicals. These silicon wafers will have two layers with different electrical properties. The top layer will have an excess of electrons, while the bottom layer will have a deficit: “holes” that an electron could jump to.
When the top layer is exposed to a strong enough light, the photons will strike some of the electrons, nudging them into the holes in the bottom layer. This creates an electric current. The typical solar panel will have around 60 solar cells, and then the current from each of these panels is combined to produce usable power.
Solar cells convert light energy into electrical power directly: there is no intervening step, no heat or steam cranking a generator. In principle a solar power system can be as small or as large as needed. But without light they are completely inert.
When and Where Nuclear Power Works Best
Once the nuclear fuel is installed and the reactor is operational, nuclear power is available at any time regardless of any external factors. The decay is constant and can be used to generate power day or night.
The reactor’s output can be adjusted to fit the demand for power: with control rods pulled back the reactor can heat up to generate more steam and more electricity. When demand is low, the control rods can be reinserted to cool the reactor down and conserve fuel.
There is no need for batteries to store power. A nuclear plant can generate power whenever it is needed and go to a low-power state when it is not.
But running a power plant is a big, complicated operation. Setting up a reactor and making it safe requires a great deal of money in containment structures and safety mechanisms. Running a reactor on a daily basis requires expertise in nuclear physics, chemistry, and mechanical engineering.
It is possible to build working nuclear reactors on a relatively small scale. The US Navy has used nuclear-powered ships and submarines for decades, and work is progressing on “microreactors” that can fit in a large truck. But these are still specialty machines for isolated locations, like military bases in far-off lands or colonies at the poles or on Mars.
Military and specialty uses aside, nuclear power is primarily for major utility companies and will remain so for the foreseeable future.
When and Where Solar Power Works Best
To work well a solar electrical system needs bright, reliable sunlight. Overcast days will reduce power generation. Even the best situated solar power system, in Australia or in the Southwestern desert of the United States, where the sun is bright and rain is rare, will be unable to generate power for close to 12 hours a day.
Timing isn’t always a serious problem. Most power demand comes during the daytime, and hot days when air conditioners ramp up power demand tend to be sunny ones. But power demand and sunlight aren’t always in synch. On hot nights, during heavy storms, or early in the evening just after sundown, demand can remain high while solar power is not available.
For solar power to fit shifts in demand on a large scale you need extremely powerful batteries that can hold charges for entire days, then recharge multiple times. This technology exists on a small scale, but larger-scale applications have yet to be worked out.
Solar power’s main advantages are simplicity and scalability. The basic technology behind solar panels is relatively simple, and maintenance is straightforward. There is little that needs to be done aside from keeping panels free from debris and checking their output periodically to make sure they are working properly. This is something a non-specialist can handle pretty easily.
Solar energy is also highly scalable — it can work at just about any size. A single solar cell can power a handheld calculator, or a couple dozen panels can power a home, or a utility can use a large array with thousands of panels to provide power for a small city. This scalability is what makes residential solar power practical for so many homeowners.
A large solar power facility will take up a lot of space, however. While a 1,000-megawatt nuclear facility will cover a little more than a square mile, a solar facility will take anywhere from 45 to 75 square miles to generate the same amount of power, depending on local conditions.
This need for space doesn’t completely rule out the possibility of building big solar power plants, but it does mean that the best locations will be unused desert areas where land is easy to acquire and sunlight is consistent. In more developed areas the land needed for large solar arrays will be much more difficult — and expensive — to acquire.
Chernobyl and Fukushima
Now we turn to consider the risks and drawbacks. And the risks of nuclear power are pretty well known. When they are well built and capably run nuclear power plants are very safe. But accidents can happen with any technology.
The Chernobyl accident of 1986 is the most infamous and by far the worst. Thousands of people were employed to contain the fire and stop the release of deadly radiation. Many of their lives were cut short because of radiation exposure and cancer.
To this day there is a danger zone extending 20 miles out from the remains of the Chernobyl nuclear power plant in Ukraine. A few hundred people have returned to the zone, and tourist groups take day trips to see the remains. But the City of Pripyat, once home to 50,000 people, is a ghost town. Ukrainian authorities estimate that it will be 300 years before radiation will subside enough to allow a large, permanent population to return.
Chernobyl was the product of a botched system test compounded by a poor reactor design and a government that treated nuclear safety as an afterthought. It is unlikely that such recklessness will be allowed, especially not in North America.
Fukushima in Japan suffered a similar accident in 2011, but this was the result of a severe earthquake and tsunami. Fukushima’s reactor was built to modern western standards, with a safer reactor design and additional containment structures that were not present in Chernobyl. The radiation released was a fraction of what came from Chernobyl. While nearby residents were evacuated, most have been allowed to return.
Chernobyl was a worst-case scenario for nuclear power, but it should be kept in perspective. It was a rare event. More than 400 nuclear power plants are operating in the world, and over the past 25 years there has not been an accident that is really comparable to it.
What Do We Do with Used Nuclear Fuel?
Since the 1950s, the United States has produced around 80,000 tons of spent nuclear fuel. This material is very dangerous, but it is safely stored either at nuclear power plants or at specially designed facilities.
Spent nuclear fuel isn’t necessarily all waste. It can be recycled and reused — many reactors in France run safely on recycled fuel, and American technicians have designs for similar reactors here.
The infrastructure for dealing with spent nuclear fuel is already in place and has already been accounted for as part of the cost of building and operating a nuclear reactor.
What Do We Do with Used Solar Panels?
No energy technology is entirely without risk. Solar energy is no exception. Solar panels contain lead and heavy metals such as cadmium. Lead is known to cause brain damage, while cadmium has been linked to lung and other types of cancer.
Solar panels do not last forever. After 25 years solar panels are usually retired. Currently the United States does not have the capacity to recycle solar panels, as is done in Europe. The know-how exists, but without further action solar panels will continue to be dumped in landfills, where there is a risk that toxic materials will leak out and pollute our soil and water.
The Bottom Line: Cost Per Power Generated
Consumers understandably want to know how much their electrical bills will cost them. Estimates of costs for different types of power can differ wildly based on capital costs, subsidies, even taxes and regulations.
But the US Department of Energy has teamed up with the National Renewable Energy Laboratory to produce what are probably the best predictions of costs for plants that are on the drawing board now and likely to be producing power in 2026 — not too far in the future. Their partnership is known as Open Energy Information. (Open EI for short)
Open EI predicts that a megawatt-hour of electricity from a solar power facility with limited battery storage will cost $47.67. The same amount of power from an advanced nuclear power plant will cost $69.39. These are “levelized” costs, meaning that Open EI attempted to account for all the variables that would affect costs.
These are estimates of costs several years in the future, and conditions may change. But they are in line with past experience. They indicate that solar power is somewhat cheaper than nuclear, but the two are close enough to be competitive.
Competitors or Complements?
If you consider global warming the chief threat to our environment, there really is no competition: nuclear and solar power are both winners. Neither produces carbon dioxide or any of the other greenhouse gasses that threaten to disrupt our global climate.
Both have something unique to contribute to our energy mix. Nuclear is a reliable source of power that we can tap into at any time, day or night, regardless of the weather. Properly monitored, it can continue to be a mainstay of utilities that can provide the equipment and expertise to use it safely.
Solar is cheap and easily scalable. It can fit into energy “niches” where neither nuclear nor traditional fossil fuel powered power plants will work. For communities where sunshine is plentiful, it provides safe power during the daytime. For residential users, it provides independence from the electrical grid and a chance to contribute to a greener environment.
If we want reliable energy, we should use all the power sources available. If we are going to pursue a green energy future that reduces carbon emissions to the minimum, it becomes even more important that we use all the methods we have that don’t emit carbon. That makes both solar and nuclear power even more valuable.
Both power sources have their advantages and their drawbacks. As the accident at Chernobyl illustrates, nuclear power involves a small but very real risk of severe damage to the local environment. This risk can be greatly reduced with improved designs and safety rules but cannot be dismissed altogether. The complexity of nuclear power means it will remain a mainstay of utility companies.
Solar power requires more space, especially for larger power plants, but it is easily scalable. A major power plant can take as much room as a city, but a rooftop can hold enough solar panels to power a home. Solar panels contain toxic chemicals that will need to be recaptured to protect the environment, but solutions are being worked on.
Solar and nuclear power both have their uses. If we want clean, reliable power we should be prepared to make the best use of both.