Invitation to Canto al Agua, Barichara

EARTH & US: World Water Day 2024…The Power of Poop!

Cathy Holt


March 22 is World Water Day, and here in Barichara we’re celebrating the first heavy rain after several months of dry season and heat and dust. Canto al Agua, a simple chant to honor and thank water, was started a few years ago by a young woman from Bogota, and last year with the help of friends as well as this year, we’ll be singing to the Quebrada Barichara, thanking the stream for its water, and asking forgiveness for the damage people have caused to it.

Imagine a world where instead of causing contamination of precious and scarce freshwater, disease and global warming…through the miracle of biogas technology, busy microbes converted the human waste, animal waste, and inedible food waste into a completely renewable energy source that can cook our food, run our vehicles, provide lighting and electricity…all while using less energy than our current waste treatment methods, and producing an excellent fertilizer as a side product?

Too good to be true? Nope.

The “Number Two Bus” in Bristol

The Number Two BioBus!

The Bristol, England “Number Two” BioBus runs on methane produced from human waste, plus food waste. (You may recall that Bristol, England was one of the most successful “Transition Towns,” and home of the local currency known as the Bristol Pound.)

“Biomethane is the fuel of the future, but it’s here now. By using renewable gas generated from food and sewage waste, we are putting the circular economy into action.” — WAYNE BOAKES, head of Renewable Energy

Most conventional buses run on diesel fuel, which produces 40 toxic air contaminants, including benzene, arsenic, and formaldehyde, as well as smog-causing nitrogen oxides. The Bio-Bus reduces those 40 pollutants by 97%.

Although some CO2 is produced, it’s 20–30% less than a diesel bus, and the BioBus is cheaper for a city to purchase than a diesel-electric bus. It’s estimated that one person’s typical food-waste and sewage generates enough biogas to fuel the whole bus for 34 miles! Now that’s what I’d call a natural resource!

GENeco, the Bristol-based waste treatment company that produces the fuel for the Number Two bus, processes millions of cubic meters of sewage waste and 35,000 tons of food waste every year at a nearby biogas digester plant. Some of the methane from the anaerobic digestion process is used to heat up the sludge, helping to create methane more efficiently. That is especially important in cooler climates like England. Another facility distributes part of the gas to power about 8,500 homes. The rest goes to a new refueling station for buses.

The following comes directly from the GENeco website,

The raw fuel

The raw fuel for this process comes from waste. Biogas is produced by microorganisms digesting organic matter in sewage sludge, liquid waste and inedible food waste, and yielding a gas rich in methane.

56,000 cubic meters a day

The amount of biogas produced daily at Bristol sewage treatment works is equivalent to the methane produced daily by all the dairy cows in Wales!

The biogas produced in digesters then undergoes processing in a “gas to grid” plant to convert it into enriched “biomethane.” Biomethane can be used as a direct substitute for natural gas in homes and vehicles — it is a sustainable and renewably-sourced alternative to fossil fuels.

Gas to grid

The gas to grid plant at Bristol sewage treatment works is the first and largest of its kind. This plant produces up to 1,900 cubic meters per hour of enriched biomethane by cleaning and upgrading the methane-rich biogas produced from the anaerobic digestion of waste.

How it works

  1. Sewage sludge and food waste is treated and pumped into a series of anaerobic digesters. The waste is heated to 32–42°Celsius (89.6 to 107.6 degrees Fahrenheit) and kept in the digesters for 12 to 18 days. During this time, micro-organisms break down the biodegradable material in the absence of oxygen to produce biogas, which contains around 60% methane.
  2. The biogas produced from the digesters then enters the gas to grid plant. The first stage upgrades the biogas to biomethane (~98% methane; 1.5% nitrogen).
  3. A bioscrubber removes gaseous impurities, such as carbon dioxide and hydrogen sulfide. Meanwhile the carbon filters release virtually odor-free emissions to the air.
  4. A small volume of propane is injected into the biomethane. This enriches the gas to the same quality and value as “natural gas” (the fossil fuel gas).
  5. The end product, enriched biomethane, is analyzed and undergoes strict quality controls before being fed into the local gas distribution network.

Green Gas Certificates

GENeco’s gas to grid facility is registered with the Green Gas Certification Scheme (GGCS), a system that tracks biomethane, or ‘green gas’, through the supply chain to provide certainty for those that buy it.

Each unit of biomethane injected into the grid displaces a unit of conventional “natural” gas. Each kWh of biomethane is labelled electronically with a unique identifier known as a Renewable Gas Guarantee of Origin (RGGO). This identifier contains information about where, when and how the green gas was produced. When consumers buy green gas the RGGO is their guarantee that the gas is authentic and has not been sold to anyone else. It ensures there is no double-counting from production to end use.

The globally-recognized GHG Protocol has recently assured that Green Gas Certificates, issued by the Green Gas Certification Scheme (GGCS), can support a business’s reporting of onsite GHG emissions, and lead to near-zero greenhouse gas emissions reporting.

Environmental benefits

The integration of enriched biomethane into the national gas grid has several key environmental benefits.

The carbon dioxide released by combustion of biomethane does not increase atmospheric CO2 ; this is because the same amount of CO2 is produced from natural decomposition of the organic matter that initially creates the biomethane.

In contrast, the CO2 released from the burning of fossil fuels (such as “natural” gas) has been locked up in geological formations for millions of years, and would not otherwise be released to the atmosphere.

Furthermore, the greenhouse gas effect of methane produced from sewage sludge is 21 times more powerful than CO2 in the shorter timeframe of 25 years. Therefore, the capturing of this methane and combustion as part of the national gas supply significantly reduces the environmental impact of this sewage treatment and food waste treatment system.

The gas to grid plant diverts inedible food waste from landfill. Adding food waste to the mixture produces twice as much biogas as sewage sludge by itself.

Refugee camps: Human waste to energy

A family of 5 can generate enough biogas to cook a meal.

2010: Environmental engineer Eckhard Kraft and his team at the University of Weimar, Germany, have been designing portable toilets using biogas technology. These toilets can thus produce methane. Kraft believes the toilets may eventually act as a source of fuel for refugee camps around the world, while also helping solve sanitation problems.

“I’m thinking of using this biogas for cooking purposes,” Kraft said in an interview. Energy shortages mean that cooking rice or other foodstuffs distributed in camps becomes difficult. “Within three or four days, people had used up all the firewood within reach. So they needed fuel.” Biofuel production onsite could help reduce costs, as less fuel and firewood would need to be transported into the camps.

At a refugee camp in earthquake-ravaged Haiti, energy-harvesting toilets used by a family of five were reported to produce an hour of biogas, enough to cook a meal.

The energy could also be used for other purposes, Kraft added. “Lighting is a huge problem in refugee camps. Providing light at night would improve safety.”

According to the UN Refugee Agency (UNHCR), some 2.4 million people around the world are currently living in about 300 refugee camps. UNHCR estimates that one-third of the camps have inadequate waste disposal and latrine facilities. Proper disposal of human waste is crucial for preventing the spread of disease.

A family of five can produce an hour of biogas, enough to cook a meal.Image: picture-alliance/ dpa/dpaweb

According to the UNHCR, an average refugee camp holds about 20,000 people. Kraft says a camp like this needs about 10 of his biogas multiple latrine units.

The waste produced by a camp’s inhabitants would not provide enough methane to meet all their energy needs, but it would make a significant contribution.

Germany currently provides the UNHCR with mobile water treatment plants for emergency use in camps around the world. Following the earthquake in Haiti, one of these mobile units provided water to some 75,000 people. Kraft would like to see his energy harvesting toilets included in the package of emergency treatment units which Germany offers.

To date, it has been difficult to raise the necessary funds to continue research and begin producing the units. Most manufacturers say they need an order of about thousand before it makes sense to start production.

Eckhard Kraft believes it is possible to make his methane extraction units safe. The gas can be transported away from the site once it has been harvested and stored in a safe facility.

Kenya’s BIOSAN Project

Innovative biogas projects are being tested around the world. In Kenya, engineers are testing units at health clinics. The BIOSAN project is headed by Sibilike Makhanu, a professor at Masinde Muliro University of Science and Technology in Kakamega.

The idea of converting human waste into biogas is gaining attentionImage: AP

“Large areas of Kenya have no running water or experience severe shortages. This includes refugee camps, schools, hospitals, slum areas in many urban centres and prisons. Schools still use pit latrines and the land has practically been exhausted,” Makhanu explained in a 2010 interview.

Aside from addressing the shortage of facilities, he explained that recycling this energy “contributes to decreasing global warming from burning methane instead of releasing it into the atmosphere.”

2018: Update on BIOSAN

In a March 2018 research paper, “BIOSAN Latrine for Refugee Camps,” by Makhanu and Waswa, the BIOSAN was described as “a hybrid of the ventilated improved pit-latrine (VIP) and biogas sewerage technologies, integrating the advantages of the two technologies while minimizing their shortcomings to enhance quality of life.”

The BIOSAN model is in use in Kakamega Provincial General Hospital, West Kenya. The system was designed to serve 150 people per day, including patients, staff, and general public. “The BIOSAN model at KPGH has provisions for harvesting the gas and packaging it in suitable containers. The packaged gas will be used in a wider user base: hospitals, schools, laboratories, lighting and emergency fuel supplies.”

“The technology is very appropriate for institutional sanitation and is therefore considered suitable for refugee camps in the intermediate emergency phase of a disaster or conflict event. Apart from providing environmentally friendly sanitation, methane is harvested as a source of energy,” wrote the authors.

Although the size of a refugee camp is supposed to be no more than 10,000 people, disasters and conflicts cause sudden mass movements of refugees. Rwandan camps in Congo in the 1990s grew to hold hundreds of thousands. One such camp had 600,000 even in 2002. Though meant to be temporary, some camps remain for decades due to unresolved conflicts. Most refugee camps are located in poor nations within Africa and Asia. “Donor nations provide fewer contributions, forcing the agencies to just maintain basic services such as shelter and food, and implement critical budget cuts on other programs.” In Tanzania, which has over 500,000 refugees, programs to improve water systems, construction of new latrines, health services and road repairs have been curtailed.

Refugee camps’ need for cooking fuel leads to deforestation with its resulting soil erosion and loss of biodiversity. Groundwater is over-extracted, exhausting local supplies. Poor sanitation and washing of laundry leads to contamination of surface- and groundwater. Environmentally safe disposal of human, medical and other solid waste is a significant problem in most refugee camps, say the authors.

Gathering wood, typically done by women and girls, exposes them to violence and takes over 3 hours a day away from wage earning and education. Burning fuelwood for cooking also exposes them to smoke, causing respiratory and eye problems. A BIOSAN serving 150 people for their cooking needs, can save over 14 tons of firewood per year.

The BIOSAN produces biogas using fixed-dome biogas plants, with up to 6 waterless pit-latrines installed around each plant. The underground part of each pit-latrine is joined directly to the digester. Human waste moves via gravity into the first compartment, then flows across a “baffle wall” into a second compartment. The whole system is designed to be watertight and gas-tight. Biogas begins to be generated when the slurry level creates a seal in the pit-latrine.

Advantages: The urine provides sufficient fluid for biodigestion to take place, avoiding the need to add water. Although the best temperature for rapid generation of biogas is 35 degrees C, sufficient biogas is still produced at temperatures of 25–30 degrees C. The latrine can be operated without major maintenance for 10–20 years, say the authors. The BIOSAN is cheaper than conventional pit-latrine and sewage systems, and provides low-cost, environmentally friendly fuel. The chances of contaminating groundwater and surface water are very minimal. It is a cost-effective technology.

“BIOSAN technology may only be an appropriate solution if at least 25 people are using the latrines, making the technology very appropriate for places with high populations such as refugee camps and public and learning institutions.”

Once a year, a tank trunk has to pump out the settled and partially stabilized sludge for further treatment, such as composting, before being used as fertilizer.

Poo Poo Power

Geneva-based inventor Océane Izard wants to use dog poop to run your electrical appliances.

Izard has come up with the “Poo Poo Power,” which can help you put your dog’s poop to good use. Instead of tossing it out, scoop it into a freely supplied biodegradable bag, and then drop both into the Poo Poo Power, which uses bacteria to break them down into methane. Crank the handle a couple off times, and you’re done! The methane charges up four batteries, which can be detached and used to run a fan, charge your phone, or whatever.

“Dog owners pick up their dog turds every day. This is certainly an ordeal. That’s why there’s so much in the streets. But with this machine, people will want to bring [home] this precious gift that their dogs give one to two times a day.”

If nothing else, having such a machine at home might encourage people to pick up behind their dogs, just so that they could save on their electrical bill. Some towns in England are using methane produced by a dog-poo digester in a public park to light a few street lamps. Actually, methane gas was first used to light gas streetlamps in England in the 1850’s. And millions of Chinese farmers use biogas in a Coleman camping lantern-style lamp with an ash mantle.



Cathy Holt

Cathy has been living in Colombia for 2 years. She’s passionate about regenerating landscapes with water retention, agro-forestry, and biogas digestors.