Got Doodoo? Make Biogas!

How many days last year did you spend caring for your Father’s creation? We all know that “tending and keeping” God’s world was the first job assigned to mankind in the Bible (Genesis 2:15), but many of us struggle to see what it has to do with our discipleship and calling. How about you?

Here in Kenya, we see a lot of day-to-day creation care by ordinary people. Maybe it’s because most people live by tending the plants and animals around them. Millions of Kenyans tend tiny postage-stamp farms: good weather and fertile soil mean the world to them.

Whatever the reason, everyone I’ve met here understands that caring for the earth is really important. I want to tell you about one I met recently. Her name is Josephine Muthone.

Josephine is a farmer. She’s an active member of the Presbyterian church. On her 1-2 acre parcel in Kikuyu north of Nairobi she milks three cows, and grows beans, potatoes, corn and other produce to feed her three children. She also grows coarse Napier grass to cut as fodder for the cows. Her husband died two years ago.

Josephine Muthone

Josephine Muthone, with tea made with biogas

Josephine works really hard. By 4:30 in the morning, she’s already walking several kilometers to the dairy co-op with her full milk jugs swinging from a shoulder harness. But while hard work is necessary, it’s not enough. Josephine used to spend lots of time, labor and money buying and carrying heavy loads of firewood for her kitchen stove. Her soil was becoming degraded, and fertilizer costs were eating into her earnings. Rains were becoming unreliable, and water was a real problem. And without a husband’s earnings or help, providing for her family was a real challenge.

But a few years ago, with the help of a local expert, Josephine installed a biogas digester in her small farm, and it’s made all the difference in the world. No more hauling charcoal and firewood; no more smoky cook stoves and harmful kitchen fumes; instant heat from free, renewable cooking gas; a steady supply of free, safe organic fertilizer to enrich her farm plot; no more runoff of harmful raw manure into the local waterways; and more resources to pay school fees for the children and improve her family’s life. What’s more, the biogas digester paid for itself in less than three years.

I met 15-20 other farmers like Josephine, and their biogas digesters were all producing great results. I’m convinced: Biogas really works.

Biogas digester under construction

Biogas digester under construction

Now you’re wondering: What’s a biogas digester, and how can I get one?

These systems are brilliant, yet remarkably simple. With no moving parts, they can last for decades. And they will provide free energy on an essentially perpetual basis. It will be necessary, however, to get your hands on 2-3 cows. (In Kenya, that’s no problem for millions of farms.)

The digester is a brick-and-cement dome built in a large pit and then buried so that only its very tip is visible from the surface.  Farmers like Josephine mix cow manure with water in a mixing chamber, and the slurry flows down into the anaerobic digester. In the absence of oxygen, bacteria and other microbes in the digester break down the manure, and the process releases methane (natural gas or CH4), which is captured in the dome above. A small valve at the top of the dome connects to a hose which feeds the kitchen stove. As the manure breakdown is completed, the slurry flows into an expansion chamber and then to a slurry pit outside – an excellent, odorless and safe form of fertilizer for immediate use in the garden.

Here are some reasons why I’m so interested in biogas for places like Kenya:

  • It’s a renewable non-polluting source of energy.
  • It reduces the dependence on firewood, and saves increasingly depleted forests.
  • It saves the time consumed by women and children collecting and carrying heavy firewood.
  • It eliminates the exposure of women and children to smoke in the kitchen, and lowers upper respiratory tract infections and eye ailments that are normally associated with the smoke.
  • The biogas slurry helps restore degraded soils and improve farm fertility.
  • Anaerobic digestion deactivates disease-causing germs and parasites, and reduces the incidence of water-borne diseases such as cholera and typhoid.
  • Biogas plants lower the greenhouse gas effect in the earth’s atmosphere by preserving carbon-absorbing forests, and by recycling the methane gas in the bio-degradable matter to be used in cooking instead of being released into the earth’s atmosphere.
Slurry mixer, with dome top beyond, use little growing space

Josephine’s biogas system: slurry mixer, with dome top beyond, use little growing space

A biogas system will cost a Kenyan small farmer about $1,200 (US dollars). That’s more than just about any have on hand, of course. But if the farmer can scrape together about $120, the carbon credits can be sold for another $120; and some NGOs offer subsidies equal to another $120. That leaves a micro-loan of about $840. That’s still a lot. But the average household spends about $280 per year on firewood, charcoal and paraffin for the kitchen. So the fuel savings can pay off the loans in three years, not counting the effect of more fertile soils and more time for productive enterprise.

Like Josephine, many Kenyan farmers are adopting biogas units. So far, about 7,000 digesters have been built in the country. The current target is 11,000, which will eliminate nearly 94,000 tons of CO2 emissions from wood burning.

But there’s a far greater problem that biogas can help address:  Roughly 128,000 acres of Kenya’s forests are cut for firewood each year. And every year, this releases about 14.4 million tons of CO2 into the atmosphere. And, with the loss of forests, Kenyans suffer more acute seasonal patterns of flood and drought, loss of habitat for many endangered creatures, and the erosion of precious topsoils.


2-3 cows provide all necessary manure

Protecting the soils, forests and ecosystems that sustain Kenya’s forty million people will require diligence and creativity on the part of everyone. To me, it looks like biogas will play an important role in the process.

If you’d like to help launch a few pioneering biogas projects in some new Kenyan communities, click here, and drop us a note. Together, we may be starting something really transformative for a community in danger.

Thanks for reading, and may God bless you.

J. Elwood


Free, instant cooking fuel! A biogas kitchen unit.

Biogas slurry makes restored this soil beautifully.

Biogas slurry restored this soil beautifully.



Leave a Reply