Coffee husks as biofuel

by on October 31, 2007

Dutch energy company Essent is the first company in the world to introduce the use of coffee husks as biofuel. The source will be Brazil, and the husks will be used to produce electricity in some of Essent’s power stations — in the Netherlands.

The husks* of this year’s harvest (estimated at 5000 tons) will be compressed into pellets and used at an Essent power station in the southern part of the Netherlands. If this works out well, another 20,000 tons will be used. Brazil could potentially produce upwards of 150,000 tons of coffee husk pellets for use annually.

On the surface, this is an appealing use of a by-product of coffee processing, but I see a few problems.

According to Essent, the use of coffee husks as biofuel could result in a CO2 reduction of at least 90 per cent. That seems remarkable. How much (carbon-emitting) energy does it take to produce the pellets?  Or more critically, how much energy and emissions are used to ship that many tons of coffee pellets from Brazil to the Netherlands?

Essent is committed to using as much biomass as possible for the production of energy.One of the company’s conditions for biomass selection is that the production of the biomass must not have any negative consequences for the food and animal feed chains, biodiversity, or economy of the countries from which the biomass comes. As we have seen in our previous post, coffee production in Brazil does indeed have significant negative impacts on the biodiversity of the country.

All coffee processing by-products are not entirely waste. Coffee pulp makes up 25% or so of the entire coffee cherry. It contains caffeine and other compounds and thus can be a bit tricky to re-use. However, it is often composted and used as mulch or organic fertilizer. Dehydrated, pulp can also be used as livestock or fish feed. Coffee hulls, on the other hand, make up less of the cherry (15%) and are already utilized in other ways. Compressed, they have been used to make logs that can be burned, bricks
used as building material, or pellets used in animal feed.

Finding further uses for coffee processing by-products close to production areas is an excellent goal. And it would seem that using coffee husks as biofuel would make a hell of a lot more sense if it was done in Brazil (or domestically in any coffee-producing nation) rather than transporting tons of them halfway around the world.

*Presumably what is meant by “husks” is the coffee parchment. The by-products produced when coffee cherries are processed are the skin and pulp, and the thin parchment covering the two beans (the parchment has a mucilaginous coating itself). The parchment is often referred to as the “hull,” is high in cellulose, and is therefore combustible.

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Revised on March 23, 2014

Posted in Coffee news and miscellany

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