It uses a wood gas generator to burn coffee grounds, thus creating combustible gas that is filtered before going to the engine.
So, where does one get enough coffee grounds to provide reliable fuel stock? Starbucks does give coffee grounds to anyone who asks for them. But since coffee grounds make excellent fertilizer and compost material, much of it is already spoken for.
More importantly, how many MPPCG (Miles Per Pound of Coffee Grounds) does it get?
That’s interesting– it uses essentially the same process as the dendro power plants of South Asia: converting wood to methane which it then burns to produce electricity. In South Asia, they use fast-growing trees, grown on-site, which they chip and use for fuel. That makes an entirely-contained, fully sustainable, CO2-neutral generating system. The same potential would be there for this truck.