Wind and solar energy are of course essential for reducing CO2 emissions, but they also have a remarkable side effect: saving lives. While leaving behind fossil fuels, renewable energy sources not only reduce carbon emissions, but other air pollutants as well. And the result is an improvement in air quality, with a corresponding drop in premature deaths.
A piece of paper inside Nature Energy delves into the weeds this week by trying to estimate the economic benefits of wind and solar energy across the US. Berkeley environmental engineer Dev Millstein and his colleagues estimate that between 3,000 and 12,700 premature deaths have been prevented due to air quality benefits over the past decade, creating a total economic benefit of between $30 billion and $113 billion. The benefits of wind turn out to be more than 7¢ per kilowatt hour, which is more than unsubsidized wind energy costs in general.
Death is in the air
Poor air quality is a tricky public health issue, as it is not clear when someone dies as a result of air pollution. The World Health Organization estimates that air pollution leads to about 7 million premature deaths worldwide each year – people die earlier than they otherwise would due to increased incidence of cancer, heart disease and respiratory disease.
In the US, air pollution is responsible for an estimated 200,000 premature deaths each year. Road transport (53,000 deaths) and power generation (52,000 deaths) are the two sectors that cause the lion’s share of the problem. By comparison, the CDC reports that heart disease and cancer, the two leading causes of death in the US, each claim about 600,000 lives in a typical year. The third leading cause of death, respiratory disease, stands at 155,000.
Air pollution is a big contributor to those totals, so renewable energy would undoubtedly reduce its contribution. And since premature deaths cost money on a societal level, renewables would also bring some economic benefits.
There are many moving parts involved in trying to figure out the economic benefits of renewables. Impact studies have been done before, but they were limited to certain regions or short periods. This study ambitiously attempts to estimate the benefits of emissions avoided by the increase in wind and solar energy from 2007 to 2015, for the entire US. Millstein and colleagues looked at carbon emissions, as well as sulfur dioxides, nitrogen oxides and particulate matter, all of which contribute to poor air quality.
There are also other factors to consider. An increase in renewable energy sources is not the only thing changing in the energy sector: fuel costs and regulations have also played a role. How much of the gain can be attributed to wind and solar energy and how much to other changes? The researchers used models that track the benefits of renewable energy as a percentage of total emissions reduction.
Regional differences also bring complexity. For example, “most wind power has been deployed in the center of the country,” the researchers write, while “solar power is highly concentrated in California.” Some parts of the country have more coal-fired power plants, and others have natural gas, which emits less than coal. To top it off, emissions regulations are not consistent across the country.
This means that the benefits of air pollution varied widely across regions. For example, a massive increase in wind energy in a region that was previously dependent on coal would significantly change air quality in that region, but a solar power plant far away from fossil fuel production would not change air quality that much. Climate benefits, on the other hand, are not regionally specific – any climate benefits in the US are good news for the whole world.
Millstein and his colleagues used a range of different models to get a sense of the full range of estimates that could be achieved by using different sets of assumptions. That means the actual benefit is probably somewhere in the estimated range.
Lives and money saved
The climate benefits of solar and wind power were substantial, but most of the benefit came from improvements in air quality. Estimates of climate benefits ranged from $5 billion to $106 billion, with an additional $30 billion to $113 billion in air quality and public health benefits. And that’s just the estimated economic benefits of the 3,000 to 12,000 premature deaths avoided — things like subfatal medical issues and lost productivity don’t count, let alone the personal benefits to individual lives.
The middle ranges of these estimates suggest that wind and solar power hold their weight despite subsidies: “total central value wind and solar air quality and climate benefits are comparable to estimates of total federal and state financial support,” the authors write. . The estimates also align with other models that have looked at benefits in specific regions, which is a good confidence check.
As emissions continue to fall, the relative improvement from renewable energy will also begin to decline. The best way to maximize investment could be to account for those regional differences, the researchers write: “wind and solar deployment in those regions of the country that provide the greatest benefits (at the lowest cost) would provide additional make profit.”
Nature Energy2017. DOI: doi:10.1038/nenergy.2017.134 (About DOIs).