identifying the optimal feed mixture. (3) Recommendations for the expansion of biogas production, including an analysis of the extent to which increasing the methane content of biogas would result in the greater use of biogas and an analysis of how the expanded use of biogas could help meet the growing energy needs of the United States. (4) Methods for productive use of nutrients recovered from qualified manure resource recovery property that benefits the agricultural economy. (b) Report Not later than 2 years after the date of the enactment of this Act, the Secretary shall submit to Congress a report on the study conducted under subsection (a).