Oregon’s anticipated budget shortfall has prompted lawmakers to consider limiting tax credits for processing livestock manure into energy in biodigesters. Biodigesters break down manure, releasing methane gas which is used to generate electricity. The remaining solids have many uses. They are expensive, and farmers have used the tax credits to offset the costs. Under House Bill 2853, tax credits would only be available for manure processed in biodigesters that were operational before the end of 2016. The credit effectively costs Oregon about $4 million a year in foregone tax revenue and has the potential to grow more expensive due to the proposed construction of a large dairy, said Rep. Phil Barnhart, D-Eugene, during a March 7 hearing on HB 2853.