Entropy Problem of Waste

David Fulford, World Biogas Expert

Last winter, as we began creating our business plan, we gradually came to realize how little we knew about biogas. Early on I contacted David Fulford at Kingdom Biogas, which operates in Reading, UK. We exchanged many emails and he debunked many of the myths I would come across. I am very indebted to him for responding to my very naïve questions. I bought his book which was very informative even though it was published in 1988. (He says he is coming out with a new book very soon.)

Then, as now, David is the right guy to talk to. He has been on-the-ground installing biogas systems throughout the developing world. When I told him about my plans in Nigeria he said, “I was there.”

As I am in London currently, I thought I would see if he was available to talk about biogas and to offer suggestions for UEnergy. Not only was he available, but he offered to meet me at the Reading train station and go out for coffee. We had so much to talk about that our cup of coffee stretched into a Pasty lunch along the canal in what turned out to be a 2.5 hour conversation! (If you are in London if you have to try Pasties, though I think they need more sauce and more flavor.)

Cornwall pasty.jpg

David and I, in general, agreed; on how to bring biogas to the world via for-profit companies, on the outdated infrastructure of the developed world and the opportunity to get infrastructure right the first time in the developing world. Waste management in North America and Europe is extremely inefficient.

To give a little background, developed countries usually combine wastewater (from the toilet) with grey water (from showers and sinks) with storm water (from rain water on the street). Chemicals in soaps, deodorants, makeup, etc that wash down the shower drain then mix with human waste in the sewer lines. Now the toilet water, which was free of chemicals, is now contaminated and the sink water which was relatively clean compared to toilet water is now contaminated with pathogens.

At the waste treatment plant, the human waste is broken down but the chemicals are not, David explained to me. And when the biosolids (digestate from human waste) is applied to farm fields, the chemicals are too. Many well-intentioned, partially-informed citizens in the US complain about all the chemicals in biosolids (digestate from human waste) that are applied to farm fields; but the chemicals don’t come from human waste—they come from personal care products. Also, draining storm water into sewage lines means that heavy rains often cause wastewater treatment plants to overflow, dumping sewage in the streams. If only cities had separate pipes for human waste, grey water and storm water!

Introducing the Entropy Problem of Waste

Vegetable waste by itself is not a waste—it is a great resource for enriching the soil. But when you mix it with plastic packaging, aluminum foil, glass bottles in your trashcan it is useless. That is because the entropy (disorder—see explanation) has been increased past some critical point. It is the same problem with human waste. Our current sewage system that combines toilet water with shower water adds a lot of water. When the water gets to the waste treatment plant, all of that water has to be removed, at great cost. Adding water increases the entropy; removing the water reduces the entropy which requires energy to be expended. Wouldn’t it be better not to add the water in the first place?

This was David and my frustration with the current model in developed countries.

The Pattern of Successful Biogas Plants

David also had key insights from his years of biogas research. In his experience, digesters serving a single family are successful. However, digesters that collect the waste from a community are not successful. This is because a single family has a strong incentive to keep their digester running, while the task of operating a community digester often falls through the cracks. This is the same reason communism has largely failed: whether I do my job or not I still get the same benefits.

On the other hand, digesters for a private organization (like schools, hospitals and factories) serving many people tend to be successful. There is an important difference between digesters operated by a private organization and those operated by a community. In a private organization there is a clear leader and he or she delegates the task of digester operation to one person. If that person fails they are fired. Accountability is very clear. Responsibility in a community is not clear.

The fourth digester category that David talked about is a large scale government owned digester. Of course there are many of these in the developed world that operate wonderfully (see previous blog posts) but in the developing world this category of digester has largely failed. David attributed this to corruption. When digesters are operated by the government every step of the way has to go through so many hoops and so many palms must be greased that in the end there is no money left. Corruption comes in the form of bidding for contracts, obtaining the necessary permits, hiring and maintenance.

This was eye opening for me. It is clear that we must create an incentive system that aligns with our goals. And we must keep interaction with the government to a minimum to maintain efficiency. Our digesters will not fit into any of the four categories above. Ours will be large but privately owned. For now, we have to start off small…

About Kyle David

Thinking about distribution in developing countries
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