You are here:

# Environmental Science/Cremation - energy used

Advertisement

David wrote at 2009-04-09 23:51:35
I am currently doing a Ph.D. dissertation on the amount of energy used in cremating bodies.  The numbers that I have found are these:

A crematory retort must reach 1200 to 1500 degrees F. to effectively burn a body.  That requires about 1.3 million BTUs and about 2400 cubic feet of gas per hour.  The average cremation takes around 2 or 2.5 hours depending on the size of the body.  You do the math.  This is a non renewable resource and if we burn (in this country alone) over a million people per year.  You do the math. Imagine that 2% of any populations will die, on average, per year, our planet has 4 billion or so people, we cremate half of that 2% giving us 40,000,000 cremations per year times 6000 cf of gas.  Let me do the math,  that is 24 billion cubic feet of gas.

All of you who think you are doing the planet a favor by cremating your families need to re-think.  When a body is buried in a very inexpensive casket there is very little impact on the environment.  "We're wasting land".  Rubbish, the land will always be there, we are merely using that portion 6 meet down.  Who is using that spot anyway?  When push comes to shove, build over the cemetery if your thoughts are to pave the world.  OR, move the headstones and plant corn or potatoes. That ground is bound to be very fertile and easy to plow.  My dissertation will end with the proposal to bury people in re-cycled product caskets and plant a tree on each grave, on which to place a marker for the family.  The tree will grown into your casket and will be giving back Oxygen to our environment and not using fuels that could heat homes.  Just a thought.

John wrote at 2009-07-23 16:01:16
Depending on the type of equipment you are using the average cremation will take 2-3 hours to complete. A standard machine will have 1 Afterburner and 2 cremation burners. An afterburner on a PowerPak II throws out 1,200,000 BTUs/hr and the cremation burners throw out 500,000 BTUs/hr each. Say an average sized person will take you 2 hours to complete and you use a)the afterburner and front cremation burner the entire two hours and b)the rear cremation burner for the final hour.

The total output of natural gas would equal 3,900,000 BTUs or 39,000cf of natutal gas.

UnclePug wrote at 2010-01-16 02:37:50
David's post misses some drawbacks, such as the embalming fluids, dental mercury and hormone medications that were in the corpse that may never break down and are considered Hazmat. No consumer would willingly buy food intentionally grown on a cemetary, this idea is a non-starter. Additionally, some bacteria and viral spores remain viable for decades or longer, so the release of pathogens would be another liability.

Cremation is a fine alternative, the reuse of the waste het is the solution. Google cyclone waste heat engine and find a video that describes an external combustion source (such as the crematory) that would link to this low-tech low speed low cost engine that could drive small-scale power generation.

Stanley Lai wrote at 2011-02-14 11:05:19
I am looking at this question at a different angle.  The data used are from the following website/web pages.

http://en.wikipedia.org/wiki/List_of_countries_by_life_expectancy

http://www.answers.com/topic/body-composition

http://healthyeatingclub.com/info/books-phds/books/foodfacts/html/data/data2a.ht

Selection of data used:

World life expectancy – 67.2 years, hence 60-69 age group.  Therefore, data used are based on this age group wherever possible.

Formula used:

q = m(t)C

Where q = heat transferred, t = the change in temperature and C = the specific heat.

Composition of human body per 100kg of human body weight:

Bone – 13.5kg

Bones consist of mainly protein and calcium compounds. However, part of

this will be taken care of as protein.

Fat – 38kg

Man – 31%, Woman - 45%, hence average percentage – 38%

Muscle and organs – 8.5kg

Man – 14%, Woman - 11%, hence average percentage – 8.5%

Water – 49.5%

Man – 52%, Woman - 43%, hence average percentage – 47.5%.

However, to make up 100%, 49% is used in the calculation.

>>>

Energy contents:

Animal fat – 40kJ/g

This figure is true if you consume the fat as food.  Fat will give off

much more energy in combustion!  However, I am happy to use

the data for the time being.

Protein/carbohydrate – 18kJ/g

This figure is true if you consume the protein and carbohydrate as

food. Protein and carbohydrate will give off much more energy in

combustion! However, I am happy to use the data for the time

being.

Bone – n.a.

>>>

Total energy gain from combustion of 100kg human body mass:

From fat:

38000g * 40kj/g = 1520mJ

From proteins & carbohydrates:

12500g * 18kj/g = 225mJ

Total energy obtainable from burning 100kg human remain: 1745mJ

The above suggested that:

1. For the value of energy per gram of a particular organic matter in

combustion shall be much higher than energy obtained as if consumed

as food by means of digestion.  That means, in real term, fewer body

is required for the same output.

2. Practically, using animal remains to generate electricity is viable.

3. The biggest hurdle now may be the efficiency of the power generating plant.

Max Dumais wrote at 2011-03-19 01:24:53
The green alternative to cremation and the land-use dilemna in cemeteries is alkaline hydrolysis or the accelerated decomposition or digestion of human remains using potassium hydroxide with 10% energy use of cremations, no toxic vapour release and a useable fertiliser residue that is currently sprayed on food crops in Ohio. The process was developed originally to dispose of mad cow disease pathogens and prions, but has been adapted by Aquamation Industries for human remains with a much safer, low temperature and low pressure system. 68% of a recent Age Poll opted for Aquamation over cremation or burial and it is acceptable to the Catholic Church and is the highest form of disposal, namely water burial to Tibetan Buddhists and Hindus. see www.aquamationindustries.com

Daniel wrote at 2014-11-11 16:20:55
The economically and environmentally sustainable answer to 'what to do with our dead' is natural burial. It is what we did before, until the Victorians imposed their black and macabre traditions on funerals.

Cremations use "about 285 kilowatt hours of gas and 15kWh of electricity on average per cremation – roughly the same domestic energy demands as a single person for an entire month" (http://www.theguardian.com/environment/2005/oct/18/ethicalmoney.climatechange). This means that every year in the UK we burn the energy demands a single person would use in approximately 450,000 months, or 37,500 years. It's just not a viable option for disposing of our dead. A lot find the crematorium process is quick and scripted, normally part of a Funeral Director's set plan. And, as UnclePug wrote, cremation contributes 16% of the UK's mercury emissions.

Normal burial is equally as wasteful, using up 3,000,000 ft² each year, and that's not including the space between graves. The process also means a lot of people are embalmed, using around 300,000 gallons in the UK each year. The majority of headstones used in the UK are imported from China and India, amassing a hugely damaging carbon footprint. And I completely disagree that we could use cemeteries for development in the future. No one would ever come round to the idea.

Natural burial is the way forward!

Cremator13 wrote at 2015-06-23 19:08:11
This website is a misnomer; there are no experts here. For those touting "natural burial" and claiming cremation is inefficient and wasteful, you should be required to dispose of your excrement in your garden and yard, and inter your dead relatives in the same spot. For the genius suggesting we use cemeteries as farmland, I don't even know where to begin. At least someone made the astute observation regarding the highly toxic chemicals in embalmed bodies, in addition, the hole is dug six feet down, but when you include the height of the concrete caisson the casket resides in, that means you have less than 3 feet of dirt atop the case. I know the UK has a lot of bad teeth and thereby many fillings, but if approximately 30 percent of the UK energy comes from coal-fired power stations, there's no way 12 percent of mercury emissions are from cremation, scrubbers or no.

Environmental Science

All Answers

Ask Experts

Volunteer

#### David L. Russell, PE

##### Expertise

I`m a Chemical,Civil and Environmental Engineer and have a number of projects in all phases of the environment. I have worked in the chemical industry and am active in professional societies, and am currently on an industrial wastes committee for the Water Environment Federation, and have taught courses in remediation in the US and abroad. I have written one book on Remediation of petroleum Contaminated Sites, and have a second book on PRACTICAL WASTEWATER TREATMENT to be published by John Wiley in September, 2006. I've also written over 30 articles on various elements of environmental problems and cleanup. Most Recently, I have addressed a NATO Scientific and Techical Conference on Ecoterrorism, and have worked with the same group on remediation of sites contaminated with Chemical Warfare Agent materials and othe materials as well. . I can answer q`s about Chemical and Environmental Engineering, land development, air pollution, water pollution, soil and water cleanup, combustion, international environmental problems, industrial processes chemical processes. Civil and Environmental and Chemical Engineering. Overall, I have over 35 years of experience in this area. Note: I do not answer homework questions

##### Experience

I love work in the third world and developing areas because it is challenging and one can get a sense of accomplishment.

©2017 About.com. All rights reserved.

Browse Answers: