Want to reduce carbon emissions? Start with these power plants

The world seems be simultaneously on fire and in flood, and the last expert report indicates that we are almost out of time to avoid even more serious climate change. All of this should lead us to look for ways to reduce carbon emissions as quickly and economically as possible.

Good news in this regard has come from the recent publication of an article that examines the contribution of individual power plants to global emissions. the to study finds that many countries have facilities that emit carbon dioxide at rates well above the national or global average. Closing the worst 5 percent of factories would immediately eliminate about 75 percent of carbon dioxide emission produced by the production of electricity.

CARMA revisited

It’s easy to think of power generation in layman’s terms, like “renewables is good, coal is bad”. To some extent, this statement is correct. But it also compresses all power generation, from “pretty bad” to “really excruciating”, into one category. And it is clear from various research that the situation is more complex. Depending on the vintage, different factories convert fossil fuels into electricity at varying degrees of efficiency. And some of the worst performing plants are only put into operation during times of very high demand; the rest of the time, they are in slow motion and produce no emissions.

The interactions between these factors determine whether a given power plant is a major contributor to emissions or just part of the background noise of a country’s carbon production. If we had a global inventory of emissions and output from each power plant, we could use this data to identify the worst offenders and make a list of goals to effectively reduce our carbon output.

In fact, we had one: the focus on the past. Using data from 2009, someone had set up the Carbon Monitoring for Action database, or CARMA. Now, nearly a decade later, Don Grant, David Zelinka, and Stefania Mitova of the University of Colorado at Boulder used data from 2018 to create an update of CARMA, providing emissions data that will probably be much more up to date.

The task was more difficult than it seems. Some countries provide detailed emissions data at the individual plant level, so their data could simply be imported directly into CARMA. But many others don’t. For these countries, the researchers relied on everything from production data obtained by the International Energy Agency to the technical specifications of individual plants.

When the researchers identified the biggest sources of uncertainty in their data, they found that they were mostly concentrated in small factories, which have the least impact on overall emissions. For large installations that are likely to be major contributors, the data is generally very good.

The worst of the worst

It should come as no surprise that all of the worst offenders are coal-fired power plants. But the distribution of the most polluting plants could include a bit of the unexpected. For example, despite its reputation as the homeland of coal, China has only one factory in the top 10 worst offenders. In contrast, South Korea has three on the list and India has two.

In general, China doesn’t have many factories that stand out as exceptionally bad, in part because so many of its factories were built around the same time, during a giant industrialization boom. As such, there isn’t much variation from plant to plant when it comes to efficiency. In contrast, countries like Germany, Indonesia, Russia, and the United States all see a lot of variance, so they are likely to have very inefficient factories that are outliers.

In other words, the authors looked at the amount of pollution a country produces from the worst 5% of its power plants, ranked by carbon emissions. In China, the worst 5% accounted for about a quarter of the country’s total emissions. In the United States, the worst 5% of power plants produced about 75% of the electricity sector’s carbon emissions. South Korea had similar numbers, while Australia, Germany and Japan all saw their worst 5% of power plants account for around 90% of carbon emissions from their energy sectors.