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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 | 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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Elizabeth Fisher (October 16, 2019 2:55 PM)
Ever since I saw the movie Dirt in which whole cows are composted I’ve wanted to be composted. I love my compost bin and what better way to make an exit.
Subramaniam Divakaran, Ph.D (October 16, 2019 7:41 PM)
Aqumation uses KOH. KOH production is also energy intensive. KOH use also need corrosion proof containers. The reaction with organic
matter also produces heat, fumes and odour that need traps to be contained. Dilute KOH Use will prolong cost and time costs. Further bones may not react unless under heat (boiling) and may need seperate disposal. I hope the total energy cost for all these factors have been considered in Aquamation. . Finally humans are energy expensive from birth to death and beyond. The donation of bodies for medical and forensic science may also help . Thanks for the thought.
Stanislav Jaracz (October 16, 2019 11:17 PM)
This whole idea of this article only diverts from the real problem, where the bulk of CO2 and environmental burden is caused by humans. The research has been done on this topic and environmental impact of burial is nowhere on the list. This article only seeds panic in people that in order to be environmental, we have to tap into the last will of what to do with our remains. It is pathetic. It is what we do during our life, not after. How we change the way we live and inspire others. We, the chemists have to take the leadership role and educate other people on the most relevant environmental technologies and science limits, not to bring confusion.
Dr. Paul C. Li (October 19, 2019 10:03 PM)
Dear KOH/water/heat Aquamation Processes Providers:
Let the souls of the passing bodies find the ways of peaceful resting and rebirth. It reminds me the uncertainty principle derived by Sir Heisenberg.
The chemistry of dissolving crab shells to make useful glucosamine keeps my perspective of Aquamation, so I am open to this option if my beloved ones agree to do so as to leave no regrets.
Thanks for your broadening chemistry of after-life. Humbly submitted Paul C. Li
Elizabeth Menkin (October 23, 2019 3:35 PM)
Just as we need itemized price lists from funeral homes, I wish we could have itemized lists of environmental costs of the various post-death body-handling options. One comment mentioned the cost of making KOH, and the narrator mentioned the cost of the headstone. Recompose creates a BIG volume of compost (due to the large amount of wood chips and straw needed to balance the body's nitrogen load) and transporting that to a woodland to spread as compost would take a fair sized pickup truck and some distance from the urban Recompose facility. Traditional Jewish burial goes without the embalming, and uses a very simple wood box (materials cost about $125 at Home Deopt/Lowes), but most cemeteries still require the concrete liner (open bottom) to keep the soil from settling and still add the need for 'perpetual care' -- but some older cemeteries in CA (where my grandmother is buried in Los Angeles, for example) have stopped watering the lawns due to the drought. All this makes it pretty hard to Go Green, and then there are all the other personal, family , and emotional factors (sending Grandma down the drain and into the metropolitan water recycling process.... if cities get cleared to put recycled water into the potable water reservoirs will we be drinking Granny?). My brain hurts.
William H. Tonn III (October 26, 2019 2:05 PM)
I read the text but did not review the video. From past newspaper reports that I have read in the last several years, the drug cartels in Mexico have been using KOH for aquamation of their victims in the ongoing turf fights,etc. Who suspected they, of all people, were being environmentally conscious?
Paul Spurr (October 28, 2019 6:00 AM)
Freeze-drying, an alternative approach not mentioned in the article, is a known, faster & somewhat more environmentally friendly method than soaking in lye.
Joe Dumais (January 22, 2020 4:46 PM)
Aquamation? With a ceremonial flushing into the city sewer? Can you then plan on annual trips to the waste treatment plant to visit dear mom and dad's resting place? Stanislav touches on the main issue, "the bulk of CO2 and environmental burden is caused by humans". A central tenant of reducing the impacts of humans on this plant should be reducing the number of humans. Not that I am advocating for this I just think it is disingenuous for "green movements" to side step this key factor. I am guess they understand it would cost them support.

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