The system: a common crop system in south Sweden: wheat (9 tons), sugar beets (60 tons), barley (7 tons). The cereal crops repeated twice.
There is a lot of residues in the system. Normally returned to the soil providing soil organic matter maintenance. But they are also a potentioal bioenergy source. Now – if the soil C maintenance is taken care of by cover crops a large part of the residues can be used for bioenergy. The beet tops for biogas. Already at this stage there is enough energy produced to compensate in excess all input energy.
We could go one step further: upgrade the cover crop to a biomass-producing second crop för biogas. That will give full energy compensation with refined biogas and in addition 5-10 Mwh of bioenergy to the society.
A system for maximizing the solar energy.
