Nuclear wins | Runner up: Solar
All energy sources generate pollution, but assessing exactly how much pollution they generate can be difficult because it’s necessary to account for the pollution generated by every part of the supply chain that leads to their production. That includes the pollution generated from mining and transporting raw materials, manufacturing and operating the power plant, and disposing of waste at the end of its lifespan. Let’s look at various types of pollution that can arise from various steps associated with most energy sources.
Mining
Water pollution can result from chemicals used to extract metals from ores and from runoff which contains heavy metals and other pollutants.
Soil pollution can arise from spills of mining chemicals and heavy metals.
Air pollution is caused by dust and diesel-powered excavators, drills, loaders, dozers, and trucks used in mining operations.
Transporting
Air pollution is caused when ships, trucks, and trains move raw materials and finished products (e.g., solar panels) used in power production.
Water pollution can result from oil and fuel spills associated with transportation.
Habitat destruction can be caused when building and expanding transportation infrastructure.
Manufacturing
Air pollution occurs from manufacturing processes, such as emissions from cement kilns and smelters.
Water pollution can result from industrial waste discharges.
Soil pollution can be caused by industrial spills and leaks.
Operating
Air pollution is created by power plants including emissions of carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter.
Water pollution can occur because of increased water temperatures from nearby power plants that use water for cooling.
Soil pollution results from particulate emissions that settle onto the ground.
Waste disposal
Water pollution can result from leaching landfills and waste storage facilities.
Air pollution occurs because of waste incineration, including emissions of dioxins, furans, greenhouse gasses, and other pollutants.
Soil pollution comes from the byproducts of energy production such as coal ash which is a byproduct of burning coal.
When we look at the lifecycle of different energy sources from mining to disposal, the source that generates the least pollution is nuclear. Nuclear produces zero emissions at the power plants. It requires the least amount of land, and it uses the fewest raw materials.
Solar comes in second place. Solar plants don’t generate emissions while they’re operating. But manufacturing solar panels uses lots of minerals, toxic chemicals, and fossil fuels. Every step in the production process requires a massive input of fossil fuels—for smelting metals from ore, for heating and driving the production processes, and for transporting the panels where they’re needed.
Solar panels require 18 times more materials than nuclear on a per unit of energy basis, and toxic chemicals like arsenic, lead, silicon tetrachloride, and hydrofluoric acid are used to make solar panels. Some people may be surprised that solar panels are associated with 20 times more cancer risk than nuclear power when considering the human toxicity potential over their whole lifecycle, according to the United Nations.
Natural gas produces more air pollution and greenhouse gas emissions per unit of energy generated compared to nuclear, wind, and solar. However, large reductions in CO2 emissions have largely come as a result of shifting electricity production from coal to natural gas. Over the past 15 years, the US reduced around 1 billion metric tons of CO2—more than the entire European Union. Natural gas reduced CO2 two times more than wind power.
Among energy-related CO2 emissions reductions:
61% came from natural gas replacing coal
31% came from wind power
8% came from solar power.
Another factor that contributes to pollution is intermittency. Intermittent power sources like wind and solar power cause unnecessary air pollution because they rely on power plants to ramp up and down quickly.
Think again of our earlier example of a small city powered by wind and solar (see Grid-Balancing Costs in Chapter 9.) Those power sources need to be backed up by more reliable sources like natural gas. But using natural gas plants as backup power sources can create more pollution than having those plants operating at their maximum capacity all the time because ramping their electricity production up and down creates inefficiencies.
As an analogy, think about city mileage versus highway mileage when you’re driving. Cars consume more fuel in the city because they’re constantly speeding up and slowing down. That intermittent use of fuel is less efficient than maintaining a constant, higher speed on the highway.
It works the same way with natural gas plants: they operate less efficiently if their output is constantly ramping up and ramping down to match the output of intermittent power sources like wind and solar. As a result, those plants generate more pollution than they would produce if they ran at full capacity.