Jane Mulberry wrote:It's a great idea, however my suspicion is that the amount of energy needed to dry and pelletise the grass might make it far from free fuel, unfortunately. If you start with 60-90 kg of grass to end up with 17-18 kg of finished pellets, that's a lot of water to evaporate off. If there was some way to utilise solar drying kiln technology for that, or somehow air dry the grass like hay without it fermenting it, the idea could be feasible. I checked a few different sources to find out the likely heat required, and it looks like doing it all inside a machine like your illustration would require approximately 35 kW of energy per 50kg of water removed.
I'd also be concerned about chemicals used on lawns being in the grass -- various herbicides and pesticides they many conventionally gardening homeowners use.