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Video: Cremation, burial, or composting? Calculating the environmental costs of the afterlife

C&EN’s Speaking of Chemistry looks at the carbon footprint we leave behind

by Tien Nguyen, special to C&EN
October 15, 2019 | A version of this story appeared in Volume 97, Issue 41


Credit: C&EN/ACS Productions

Cremation and ground burial both have carbon footprints that have some people looking for other options for the afterlife. Proposed ecofriendly and chemistry-centered alternatives include a process called aquamation, which dissolves bodies in a warm base bath, and human composting, which was just legalized in Washington State. But is one better for the Earth than the others? With the help of some animated gingerbread, C&EN breaks down the processes to see how our options for the hereafter stack up.

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The following is the script for the video. We have edited the interviews within for length and clarity.

Tien Nguyen: When we die, do you ever wonder what happens? I mean, to the Earth? Well, that depends a lot on how we reach our final resting place.

Ground burial and cremation are two of the most common ways to go. But there’s a growing list of chemistry-centered alternatives that are being marketed as having less of a carbon footprint.

One is human composting, which just became legal in Washington State.

How much better are those alternatives for the planet? Which method is best? The answer is not straightforward.

But here’s what the latest research tells us about the overall costs of how we lay our dead to rest.

Let’s start with the most common methods. In 2017, 50% of people in the US chose cremation versus 43% who chose burial.

Burials put a lot of material into the ground in the US. We’re talking 16 million L of embalming fluid and about 47,000 m3 of wood for coffins every year.

By some estimates, a single cremation puts about 190 kg of carbon dioxide into the air—the equivalent of driving 470 mi in a car. And there’s more.

Dozens of materials and processes are involved in both cremation and burial, according to an exhaustive study done by Elisabeth Keijzer in the Netherlands in 2017.

For example, the environmental impact of an average headstone includes not only raw materials like granite but also the electricity used to run the engraving machine, as well as the CO2 released when transporting the headstone to the cemetery.

All told, the study breaks down the environmental tolls of ground burial and cremation into 18 different categories.

Even though a single cremation emits about double the amount of CO2 as a ground burial, when Elisabeth Keijzer added up all of the 18 impact categories, she found that burial actually has more environmental impact than cremation.

That’s because of land use.

Land use takes into account things like the energy needed to mow cemetery lawns and the water needed to keep the grass green.

Not everyone agrees about the impact of land use on burials. According to environmental analyst Troy Hottle, it all comes down to what the land was or could be used for.

For example, if instead of a cemetery, the land was used for a park that would still need regular mowing and watering, it doesn’t really make a difference to the environment. Turning it into a natural wooded area, lowers its impact.

Remember, I did warn you that this wasn’t going to be straightforward. Still, let’s not lose perspective.

However you factor in land use, the ground burial or cremation of one person doesn’t have a huge environmental cost. But there are a lot of people out there, so anything that can cut the energy and resources needed to get us to our final resting place will benefit the planet. Which is why some people are looking for greener ways to go.

One of these is a process called aquamation that is, essentially, a way of dissolving a body. It uses a heated bath of potassium hydroxide and water and can be safely disposed down the drain. Aquamation uses a fraction of the energy of traditional cremation. It’s already used for our dearly departed pets and is legal for humans in some states.

Another option is turning corpses into compost, which was recently legalized.

Lynne Carpenter-Boggs is a soil scientist and science adviser for Recompose, previously known as the Urban Death Project. Her team just completed a human-composting pilot trial with six donated persons.

She says human composting works just like regular composting. But, you need to replace the typical manure and food scraps used in gardens with more socially acceptable materials, like wood chips and straw.

To get microbes in this soil and compost mixture to break down a body fully, Lynne says, her team had to strike the right balance of carbon and nitrogen. As in regular composting, bacteria chow down on carbon-containing matter, while nitrogen supports their growth. Too much carbon can slow down the process, while too much nitrogen can create an unpleasant ammonia odor. Like regular compost, Lynne says, human compost can enrich the earth.

Lynne Carpenter-Boggs: This is something that actually adds to the health of whatever ecosystem the material is going to.

Tien: Recompose plans to launch a human composting facility in 2021. The company says the compost soil can be returned to families or used for gardens on-site. For now, there are other ways to reduce your environmental impact, even when it’s not your funeral.

Elisabeth Keijzer found that a funeral service can actually produce three times the environmental impact of the ground burial itself. This is because of the carbon footprint from guests traveling, food being prepared, and flowers being grown for arrangements. So something like carpooling instead of flying could make a difference.

Other green burial techniques involve skipping the embalming process or choosing an ecofriendly casket. For example, replacing the cotton coffin lining with a material like vegetable-fiber jute can lower the lining’s impact by 86%, according to Elisabeth Keijzer’s report.

Of course, choosing how you want to go is deeply personal for you and your loved ones. But it doesn’t hurt to understand the environmental impact of the inevitable.

Have your thoughts changed on how you’ll be buried or cremated? Let us know in the comments! And thanks for watching.

Note: At the time of recording, Recompose was planning to launch in 2021. As of Oct. 14, 2019, their website is suggesting that they are ahead of that schedule, indicating they will be operating in Dec. 2020.


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