VeerChand Bothra (Mobile Pundit) points to an article in India's Financial Express, Dung to power mobile technology in rural India. I found this interesting as, on my last day at 3GSM in Barcelona, I spent a few minutes at Ericsson's display of the bio-diesel plant that is the subject of the Financial Express article.
What's not described in any of the coverage I've seen, is how these systems actually work. According to the Ericsson fellow working the booth at 3GSM, the technology is already in service in several developing countries. What's new its use to power mobile cell sites.
Typically one biodiesel plant produces a lot more fuel than you need for a single cell site, so instead there's one plant for several dozen cell sites. Peak production is 2500 liters of diesel every 10 hours. In one approach, a farmer's co-op runs one of these plants and owns a (diesel-powered) tank truck. They contract with the local mobile phone company to supply biodiesel to a group of cell sites, then deliver the fuel by truck to the various cell sites.
The point is to deal with locations where imported diesel is expensive and/or the supply is unreliable.