New York Dairy Manure Management Greenhouse Gas Emissions and Mitigation Costs (1992-2022).

Livestock manure can be a significant source of greenhouse gases (GHG) including methane (CH) and nitrous oxide (NO). However, GHG emissions are strongly affected by the type of waste management system (WMS) used. For example, CH emissions increase substantially under anaerobic conditions that occur in many WMSs. There is a need for improved estimates at regional and national scales of the effect of WMSs on GHG emissions and identification of opportunities and associated costs to mitigate these emissions. As New York State is the fourth largest dairy producer in the country, our objectives were to quantify (i) the changes in WMS and associated GHG emissions over time, (ii) a methane conversion factor (MCF) derived from existing data from three covered manure storage units in New York, and (iii) the benefit and cost of installing covers and flares to destroy CH from existing storage units. We found that GHG emissions from changing manure management increased from 0.7 Tg carbon dioxide equivalents per year (COe yr) in 1992 to 1.6 Tg COe yr in 2012. We derived an MCF of 0.61 based on data from dairy manure storage units with covers that captured and flared CH in 2010 and used this MCF to project GHG reductions for a statewide mitigation scenario in year 2022. This scenario, covering and flaring CH from 662 manure storage units, mitigates 1.8 Tg COe annually or 62% of manure GHG (CH and NO) at an estimated cost of $224 million ($0.005 L milk or $13 Mg COe).