This post was originally published in Power Letter, a weekly newsletter about news and trends in renewable energy. You can subscribe at pwrltr.com.
Discussions about renewable energy generally revolve around solar and wind power. There are good reasons for that. They are the most scalable and affordable options in our arsenal at the moment. Solar power is now the cheapest form of electricity in the world, and its deployment remains a high priority.
But solar and wind are far from being the only players, and the conception of their dominance depends on your definition of renewable.
Taking Renewable Energy Literally
In the strictest sense, “renewable” just means a resource can be used and replenished. More can be used without running out. In the context of energy, this is in contrast to the finite resources that we have used for power in the past (and continue to use), like coal, oil, and natural gas. We don’t seem to be staring down the barrel of running out any time soon, but a limit does exist. Sunshine and wind, on the other hand, aren’t going to run out.
Hydroelectric power, which produces energy from moving water (usually via dams), also fits the “renewable” label. Rivers and reservoirs refill each year, allowing for ongoing power production. However, droughts can reduce hydroelectric potential temporarily, though such events have proven to be short-lived overall.
Nuclear power is generally not considered renewable by this definition because the type of uranium that is needed for the production of nuclear power is finite.
There are also other, less-discussed and less-utilized options, like geothermal, wave, or even sidewalk electromagnetic induction that may see expanded adoption in the years to come, but those are a subject for another day. For now, we’ll stop here.
The Environmentalist Definition
One common conception of renewable energy is that it only includes sources of power that are perfectly eco-friendly. Of course, no source of energy is perfectly eco-friendly, but the degrees of environmental impact certainly vary wildly.
Hydropower, for instance, can disrupt aquatic ecosystems, alter fish habitats, and affect water quality. For some, these impacts are enough to exclude it from the “renewable” classification.
Nuclear power has its controversies as well. Anxiety about nuclear power looms large in the public psyche. Whether it ought to can be debated (a subject for another day), but concerns over safety and waste management lead some to see it as insufficiently eco-friendly to be considered renewable.
Even solar and wind are not without environmental impact. For example, mining operations for the minerals and metals required by renewables can have a significant environmental impact locally.
Of course, none of these issues compare with the havoc wreaked upon the world by fossil fuels. I may touch on this more in the future, but for now, I’m going to assume a basic understanding of climate change and its dangers. Nothing else the human race does has as much of a negative impact on the earth as the burning of fossil fuels.
The Climate-Friendly Definition
This leads us to our next definition. In public policy, renewable energy is generally framed in terms of its role in mitigating climate change. By this definition, renewables are anything that doesn’t release carbon dioxide or other greenhouse gases into the atmosphere.
All of the options in our first definition fit this one. But “renewable” is kind of a misnomer for this version, or at least beside the point. This framing doesn’t care about whether or not it runs out. It is only concerned about whether the energy source will worsen climate change.
Though the juxtaposition of fossil fuels vs. renewables is a bit imprecise, the categorizations generally work.
However, there are exceptions to the renewables = climate-friendly way of looking at things. Biomass fuels are a broad category that encompasses anything that comes from something living. This can include anything from ethanol made from corn to wood-burning stoves. They are renewable in that you can just grow more without running out (if done responsibly), but their use releases greenhouse gases and contributes to climate change.
Nuclear power, on the other hand, does fit the climate-friendly definition of renewable. Though waste is produced, that waste is going to be buried deep in the earth for thousands of years, having no effect on the climate. People are sometimes surprised to hear climate activists advocating for the use of nuclear power, but it’s a question of priorities. Is it more important to eliminate fossil fuels or nuclear power first? Hopefully, sometime in the future, it won’t have to be a choice, but for now, there’s a tradeoff.
If we use the climate definition to classify renewable energy, solar and wind are not as dominant as they may seem. According to the US Energy Information Administration (which groups hydropower with renewables but gives nuclear its own category), solar is about 4% of current US utility-scale production, hydroelectric is about 6%, wind is 10%, and nuclear is head and shoulders above the rest at 19%.
In practice, the public policy definition of renewable also has to take into account political realities, which can often exclude nuclear, and feasibility, which can make new hydro construction difficult.
So who gets to decide which definition of renewable energy is used?
The short, but not very helpful, answer is: It depends on the context.
With that in mind, the slightly longer answer is that for most contexts, we have to acknowledge the central role of public policy. Government, and those who influence it, in many ways determine the priorities of society. They set the agenda and decide who gets tax incentives and grants.
The Inflation Reduction Act (IRA) is the perfect example of the government setting the ground rules. The funds made available through the IRA have produced a massive expansion in the renewables industry in line with the priorities they set. (That said, the technologically-agnostic approach of the IRA is a great example of government setting the ground rules without micromanaging.) Of course, these priorities are set in collaboration with business and other stakeholders.
So, for practical purposes, the climate-friendly definition has become dominant, and for good reason. Government, business, and society at large are throwing money at renewable energy because it’s needed urgently to combat an unfolding crisis that is staring us in the face.
