Some of the possible income sources from an anaerobic digester are electricity, heat, tipping fee, and digestate. Electricity and heat require someone to want to purchase them, and a way to provide it. Tipping fees can be used when removing waste from a plant, and can increase methane. Digestate is less odorous fertilizer option, and could potentially be sold at enough to cover transport costs. Selling electricity is complicated by the need to be attached to a grid, whether electricity will be sold back at a higher price, and metering. Heat can be used on site, but utilization is a problem. Tipping fees rely on a steady source, and the digester volume has to be larger. Digestate income relies on storage, and a demand for it.