Climate Action and Solutions. Waste-to-Energy
By: Erik Marcotte
Tags: Waste To Energy, Municipal Solid Waste, Climate Mitigation, Climate, Climate Change

Intro

Landfills — there are so many landfills and extra amounts of waste out there that just sit and ferment powerful greenhouse gasses into the atmosphere. Much of that waste is polluting our land and water ways. According to estimates made in 2015 by the United States Department of Energy, the average amount of municipal solid waste (MSW) produced per United States citizen, per day, is approximately 4.4 pounds. No matter your reason for opening this blog, I am sure glad you did because this entry will teach you how your 4.4 pounds of MSW could aide in reversing the negative outcomes of climate change, rather than continuing to degrade the natural environment. This would be achieved by divesting from the world’s fossil fuel energy sources and utilizing waste-to-energy plants to bridge us into a world of renewable energy.

The Hot History of Waste-to-Energy Combustion

If you have never heard of waste-to-energy before, then read up because you are a bit behind in the game. Way back in 1885, the United States built its first trash incinerator near Pittsburgh, Pennsylvania.

Since then, the United States and many other countries have continued to take advantage of waste-to-energy benefits. Some countries, like Japan, have even adopted waste-to-energy to such a degree that the majority of their MSW is used for energy recovery purposes.

The above chart proves that there is still an international interest for utilizing waste-to-energy combustion, although the reasons behind each countries decision to use this technology varies. For small countries like Japan, waste-to-energy plants do not only produce necessary power, but they give a place for trash to go; a much-needed aspect for countries who have limited space. On the contrary, large countries like the United States use waste-to-energy combustion to reduce the frequency of burning fossil fuels. Used in these ways, waste-to-energy becomes the transition tool to move form depletable energy sources to completely renewable ones.

The Energy Conversion Process

The process of converting municipal solid waste into electrical energy goes as follows:

1. Municipal solid waste is extracted straight from landfills, or taken directly to a waste-to-energy plant by waste management services.

2. That solid waste is then transferred into a massive combustion chamber where it is burned in either the presence, or absence of oxygen. The decision of whether to use oxygen, or not, relies on the specific variations of waste that was collected.

3. When the waste starts to burn it produces heat — as one may expect.

4. A boiler is heated as a result of the high combustion temperatures and starts to produce steam

5. That steam is then directed to a steam turbine to rotate the blades and produce electricity.

6. In the meantime, all the toxic gas that was released during the combustion process is treated for pollution and then let out of a smoke stack

7. The last step of the process is to deal with the remaining ash.

Cool right? The illustration below should help you visualize the above process:

An Image of the combustion process of municipal solid waste in a waste-to-energy plant. Used for a better comprehension of the inner processes of waste-to-energy pants. Photo credit: deltawayenergy.com

Environmental Costs and Benefits

Now typically we burn fossil fuels for most of our energy needs, but since the Clean Air Act of 1970 was enacted, there has been international pressure to reduce the amount of carbon containing emissions that humans produce. In fact, during the 2016 Paris Agreement, international leaders set a worldwide goal to reduce the emissions of greenhouse gases enough to keep rising global temperatures under a change of two degrees Celsius. That might sound small, but it is actually quite significant and will cause much worse environmental damage then the we have already seen in the past few decades. Eliminating methane and carbon dioxide are the main benefits of waste-to-energy that will help keep the climate under the two-degree threshold. Looking at the environmental factors, the waste-to-energy process helps eliminate any methane that would otherwise be released while sitting in a landfill. Waste-to-energy, also, has the ability to reduce a total amount of two to three gigatons of carbon dioxide in the atmosphere by the year 2050, according to the climate mitigation website, “Project Drawdown”.

Co-Benefits — What other ways does waste-to-energy help the environment?

First off, what the heck is an environmental co-benefit? Well a co-benefit is a positive effect on something that happens in addition to the intended purpose. Therefore, an environmental co-benefit is one that, not only, mitigates climate change directly, but also effects the subsectors of environmental degradation. In the above section, I described that the intended purpose for switching to waste-to-energy is to reduce the amount of sources we use for energy production, and to cut carbon emissions to stay under the temperature threshold. in this next section, I will talk about the other benefits that come with processing MSW with waste-to-energy combustion.

The environmental co-benefits of waste-to-energy are — but not limited to — a place for trash to become reusable, depleting landfills and less over all waste, and cleaner ecosystems. My personal input on waste-to-energy is that it is an innovative way to combine what we throw away as useless trash, and cleverly make use of its stored energy to reproduce what created the waste in the first place. This system has turned human-made, end-life, products into renewable energy sources — and that is pretty cool.

During my research on the co-benefits, I came across a statistic provided on United States Energy Information Association’s website. The website said that burning MSW can reduce the volume of landfills by approximately 87%. This is an extraordinary amount of landfill space that could become available to house all the waste that did not make into the landfills. Take into consideration that there is already so much excess trash in the world that there is a legitimate island of trash floating in our oceans. Why would we not want to put all of that stored up energy into regenerative processes while also saving water-based ecosystems? If the current scale of waste-to-energy operations continue to be implemented, not only would we redirect the production of a significant amount of energy, but we could also relocate the waste that has made its way into our land and water ways. That could even have resulting benefits on the world’s ecosystems that are currently suffering from human pollution.

Costs — What are the environmental costs of waste-to-management

The environmental benefits of waste-to-energy seem nice when you gain an understanding of them compared to those of fossil fuels, but to think like a true scientist, one must think of both sides of the equation. The environmental cost of the waste-to-management process lie mostly in the emissions and the toxicity of bottom ash. Bottom ash is the heavy, metal-containing, ash that is left over after burning MSW. Bottom ash can be toxic and leach chemicals into the surrounding environment if is not properly treated before brought back to the landfills.

It is true that taking waste from landfills can reduce the amount of methane emissions, however inadequate ways of treating the combustion emissions could substitute the reduced levels of methane for significant amounts of carbon dioxide. It is important to note that the waste-to-energy process trades methane emissions, which is an intense greenhouse gas, for carbon dioxide, which is less potent, but longer lasting in atmosphere. If we want to become an emission free world, then it would seem wise to use waste-to-energy as a transition away from fossil fuels to renewable energy, rather than using it as a complete solution.

Economic Costs and Benefits

Waste to energy is sadly not a very cost-efficient solution for mitigating climate change. It costs between $134.69–149.92 billion U.S. dollars just to implement, and the funds to maintain the plants are quite high, as well. This problem could be solved with the advancement of affordable technologies and operational methods to focus on expanding the market. Right now, some of the largest costs of waste-to-energy is the treatment and exportation of bottom ash back to the landfills. Finding out ways to further utilize bottom ash is a good step in the right direction. Current treatments of bottom ash, like extracting and selling its heavy metal components, or using properly treated bottom ash to make construction material, has proven to help balnce the operational costs of waste-to energy.

References

Thorneloe, Susan, and Ozge Kaplan. Optimizing Resource and Energy Recovery for Municipal Solid Waste Management. U.S. Environmental Protection Agency , 10 June 2016, https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NRMRL&TIMSType=&count=10000&dirEntryId=322486&searchAll=&showCriteria=2&simpleSearch=0.

U.S. Department of Energy. Waste-to-Energy from Municipal Solid Wastes. U.S. Department of Energy — Office of Energy Efficiency and Renewable Energy, Aug. 2019, pp. i–28, https://www.energy.gov/eere/bioenergy.

US EPA, OLEM. “Energy Recovery from the Combustion of Municipal Solid Waste (MSW).” US EPA, 24 Mar. 2016, https://www.epa.gov/smm/energy-recovery-combustion-municipal-solid-waste-msw.

“Waste to Energy.” Energy.Gov, https://www.energy.gov/eere/bioenergy/waste-energy. Accessed 20 May 2020.

“Waste-to-Energy (MSW) — U.S. Energy Information Administration (EIA).” U.S. Energy Information Association , 4 Dec. 2019, https://www.eia.gov/energyexplained/biomass/waste-to-energy.php.

“Waste-to-Energy (MSW) in Depth — U.S. Energy Information Administration (EIA).” U.S. Energy Information Assosiation, 6 Feb. 2020, https://www.eia.gov/energyexplained/biomass/waste-to-energy-in-depth.php.

Yedla, Sudhakar, and Jyoti K. Parikh. “Economic Evaluation of a Landfill System with Gas Recovery for Municipal Solid Waste Management: A Case Study.” International Journal of Environment and Pollution, vol. 15, no. 4, 2001, p. 433. DOI.org (Crossref), doi:10.1504/IJEP.2001.004834.

— -. “Economic Evaluation of a Landfill System with Gas Recovery for Municipal Solid Waste Management: A Case Study.” International Journal of Environment and Pollution, vol. 15, no. 4, 2001, p. 433. DOI.org (Crossref), doi:10.1504/IJEP.2001.004834.