Why California's carbon manure math doesn't add up
California's plan to use manure-based biomethane to reduce carbon emissions from transportation is flawed because it relies on questionable accounting methods. The state's Low Carbon Fuel Standard awards credits for capturing methane from manure lagoons, but research shows the actual climate benefits are far smaller than claimed, potentially worsening overall greenhouse gas reductions.
Background
- California's Low Carbon Fuel Standard (LCFS) gives lucrative credits to dairies that capture methane from manure and turn it into renewable natural gas (RNG). Critics say the program's carbon accounting is fundamentally flawed.
- The key problem: LCFS credits compare RNG to a fictional "baseline" where manure sits in open lagoons emitting all its methane. But many California dairies were already capturing methane before enrolling — so the real emissions reduction is much smaller than claimed.
- This is an "additionality" failure: carbon credits should only reward cuts that wouldn't happen otherwise. Paying for existing practices inflates climate benefits and wastes subsidies.
- Also, the RNG is burned in trucks, releasing CO2. The carbon math treats that combustion as free, counting only the avoided methane — which critics say is double-counting.
- The debate mirrors wider fights over carbon offsets and bioenergy: are we creating perverse incentives for bigger herds and rewarding business as usual?