For transport energy one competing

4.7. Environmental impact
Assuming there are no biodiversity issues related to the location of the plant, environmental impacts can be broadly divided into three categories for consideration. Firstly there are those impacts related to substances discharged into the environment. In this process the discharges are compost and effluent from the Tanespimycin digester, and exhaust gases from the combustion of biogas.
Anaerobic digestion is an established technology which has been used with many kinds of farm wastes, municipal solid waste and human effluent. No environmentally toxic substances have been introduced into the cellulose to ethanol conversion process, so it is unlikely that any insurmountable obstacles to clean performance would be encountered. Nevertheless, monitoring would be necessary since there is the potential for pollution of air, soil and waterways. It is proposed that, with proper land management, a net sequestration of carbon is possible because of the return of compost to the soil. In practice soil carbon levels would need to be monitored to determine whether or not this was happening.