The beans must have pulp removed and the jellylike mucilage around the seed washed off. After that, they must be gently dried.
Typically, the pulp is stockpiled but can wash into creeks and rivers when it rains. The musilage-contaminated water also goes back into waterways. Too much of either can kill fish and make the water undrinkable.

Thomsen and Birgitte Ahring, director of the WSU center, have been tapped by the U.S. Department of Agriculture to help develop a biogas-production demonstration project in Honduras to help solve the problem. It will be based at Honduran Cafe Institute, a nonprofit, that employs Zuniga and Gamboa Morillo.

The project is planned to demonstrate that pulp and musilage can be turned into biogas that farmers can use to dry coffee, Zuniga said.
“Farmers will develop more,” she said. “By drying coffee, they could get a better price for coffee.”

Coffee is seasonal, and during the rest of the year, the digesters that produce biogas could be fed with manure or chopped-up green waste, Thomsen said. Farmers are constantly removing brush to maintain coffee production and in some cases banana production from trees that are used to shade the coffee plants.

When not needed for coffee processing, the biogas could be used for heating or cooking, both of which now may be done by burning wood. Using biogas instead would not only reduce the smoke inside Honduran homes, but also help prevent deforestation.

Zuniga envisions the biogas eventually used to produce electricity for communities…

Excerpts above from TRI-CITY HERALD’s article: “Engineer, assistant learn to use waste to produce biogas” by Annette Cary.