Waste-to-Energy Emissions Cleaner than Coal?

Images courtesy of Greening Forward and The Energy Recovery Council

There’s been a shift in recent years from traditional coal and nuclear power plants to more sustainable alternatives like waste-to-energy (WTE) plants. Are these “greener” facilities actually producing cleaner emissions compared to traditional power plants?

What is Clean Coal?

“Clean coal” is in the news quite a bit these days, but many people don’t understand exactly what clean coal actually is. There’s no such thing as clean coal – coal is all the same.

The term “clean coal” was simply an ad campaign launched several years ago funded mostly by major coal mining companies and other coal supporters.

The whole clean coal initiative isn’t all smoke and mirrors, however. It does involve some pretty substantial upgrades to coal power plants that would greatly reduce emissions. However, the expense of such upgrades is high and it’s quite an undertaking. It wouldn’t be until at least 2020 that all major coal power plants received the clean coal upgrade.

Waste-to-Energy Plants

I won’t delve too deep into the inner-workings of a waste-to-energy facility because it’s beyond the scope of this article, but you can read a more in-depth article here.

A waste-to-energy plant basically takes municipal solid waste (MSW) and burns it to produce energy. These power plants are also called municipal waste combustors (MWC) or municipal solid waste combustors (MSWC). It’s sort of a power plant fueled by garbage.

There are only about 86 waste-to-energy facilities in the U.S. but more are planned to launch soon. These plants are very expensive to create compared to a traditional landfill, so the cost factor is the major reason many cities across the U.S. are sticking to traditional landfilling instead of switching to MWCs.

Coal vs. Waste-to-Energy Emissions Comparison

It wasn’t long ago that coal power plants and MWCs were comparable in terms of the amount of pollutants released into the air, but that started to change in the past decade or so. The change occurred thanks to the Clean Air Act, originally enacted in 1963 but expanded upon several times over the years.

By 1990, the EPA added the Maximum Achievable Control Technology (MACT) standards under the Clean Air Act. This greatly improved MCW emissions (more on that later).

The Clean Air Act has helped significantly reduce air pollutants from all sources, particularly since the 1990 amendments. EPA statistics show the total amount of air pollutants released into the air between 1990 and 2005 dropped more than 94-percent. This includes pollution from power plants, automobiles, and other industry.

Taking a look at the statistics comparing coal and waste-to-energy emissions, MWCs excel in most categories. According to a collaborative research study published at Columbia University in 2003, WTE facilities have lower emissions of sulfur dioxide, particulate matter, and nitrogen compared to coal-fired power plants.

On the other hand, WTE emissions of hydrogen chloride are five-times higher than coal plant emissions. The report also states emissions of mercury, lead and cadmium are nearly identical in both coal and WTE power plants. Dioxins, cancer-causing pollutants, released by coal power plants exceeds that of WTE facilities.

2002 statistics show WTE facilities released about 0.96-percent of the total airborne dioxins in the U.S. while coal-burning plants released five-percent.

epa graphs air pollution emissionsImages courtesy of EPA.gov

Greenhouse Gases

As you can see from the table below, MWC plants release less CO2 into the air per megawatt of power generated compared to coal. In fact, it also beats out oil and natural gas.

The EPA estimates coal-burning plants and other fossil fuels account for about six billion tons of greenhouse gases released each year. WTE plants, on the other hand, release approximately 10 to 20 million tons per year.

greenhouse gases released by power plantsSource: EPA.gov

An additional benefit of waste-to-energy facilities, according to the EPA, is the reduction in greenhouse gas emissions compared to landfilling the waste. For every ton of municipal waste combusted rather than landfilled, one ton less greenhouse gas is released into the air.

What does this all mean?

It’s clear that WTE plants are the superior choice over coal-burning plants when it comes to emissions. MWC plants release far fewer toxic chemicals and greenhouse gases compared to coal and are continuing to improve upon these numbers as the technology advances.

Between 1990 and 2005, waste-to-energy facilities have improved dioxin emissions by more than 99-percent; mercury, cadmium and particulate emissions by 96-percent; and lead emissions by 97-percent, according to a 2007 memorandum released by the EPA.

These improvements are astounding, and my guess is that these figures will continue to improve as WTE technology advances. All that said, coal makes up about 42-percent of the total electricity generated in the U.S. as of 2011.

So, there’s still a long way to go before our nation switches from non-renewable energy sources, such as coal, over to more sustainable sources like WTE, solar, wind and hydroelectric power.

Return to the Hometown blog to read our latest posts