Dairy Methane and Manure Management Op2ons for GHG Mi2ga2on

Transcription

1 Dairy Methane and Manure Management Op2ons for GHG Mi2ga2on Steve Zicari, PhD, PE UC Davis Biological and Agricultural Engineering Department CalCAN Summit February 28, 2017 Science of Dairy Methane Reduc2on Prac2ces Workshop

2 Simplified The science of methane produc2on Aerobic (+ Oxygen) CO 2 + H 2 O+ Biomass Nitrates? Phosphates? Sulfates? VOCs? N 2 O?... Air Water Organics (Vola=le Solids) Anaerobic (- Oxygen) CO 2 + CH 4 + Biomass H 2 S? Ammonia? VOCs?... Air Water Global Warming Poten=als (100-yr AR4) CO 2 CH Life=me ~12yrs 4 N 2 O Short Lived Climate Pollutant

3 Not so Simple The science of methane produc2on Methane produc2on impacted by: Microbial Communi2es Feedstock Characteris2cs Composi2on (VS VS) Nutrients Inhibitors Alkalinity/buffering, etc Environmental Condi2ons Temperature, ph, redox poten2al Mixing, wind speed, etc., etc

4 Highly Integrated Manure Mgmt. Systems Fresh Water, Feed, Bedding, Other Inputs Recycled Liquid Feed Irrigation Water + Fertilizer EPA Methodology adapted by ARB for GHG inventory calcula2ons. CA source data being inves2gated. Adapted from USDA 210-VI- AWMFH (2011)

5 CA Dairy Manure Methane Emissions Sustainable Conservation (2015):

6 Livestock GHGs ~2% Enteric 75% Dairy Agriculture ~8% of CA GHGs (2014 CO 2 eq) CA Dairies support 20% of US milk consump2on with very high milk produc2vity per cow ~2% Manure Management 97% Dairy 85% CH 4 75% Lagoons

7 CA Dairy and Cow Numbers 50% of cows on largest ~225 dairies (or smallest dairies) Median herd size ~2000 milking

8 Manure GHG Reduc2on Strategies: Costs? Focus on Anaerobic Lagoons: Reduce emissions or capture and destroy Many other scenarios exist Kaffka et al. (2016):

9 Other possible strategies may warrant addi2onal inves2ga2on

10 Study Methodology For each alterna2ve scenario: 1. Cost and poten2al GHG mi2ga2on informa2on was collected. 2. Cost informa2on was es2mated for 300, 750, 1500, 3000, 5000, and head MODEL dairies assuming ~60% manure VS des2ned for a lagoon. Scrape and dry conversions assume parlor flushing leaves 15% VS des2ned for lagoon. 3. Cost regressions were generated for the range of dairy sizes and applied to the statewide dairy database informa2on. 4. GHG reduc2ons were es2mated compared to baseline emissions.

11 Mi2ga2on Scenario Results Summary 10-year costs $1-3 + Billion Kaffka et al. (2016):

12 Covered lagoon or AD systems Adop2on on largest 225 farms ~50% GHG reduc2on Hurdles: High capital costs, low energy values, uncertain environmental credit markets, involved permimng and interconnec2on issues, possible increases in criteria pollutants with certain biogas uses Opportuni=es: Easily integrated in dairy design, possibly improved fer2lizer characteris2cs, enables codiges2on of other feedstocks and implementa2on of more advanced downstream treatment technologies

13 Conversion to scrape demands aerobic/dry manure management system or more frequent applica2on Uncertain emissions profiles while drying Significant capital and opera2ng expenses for solid manure produc2on and handling Water savings???

14 Scraping Systems

15 Scrape Scenario Example: Compos2ng ~46% reduc=on in baseline GHGs BeZer emission rates needed Bulking choice cri=cal: Costs dominate wide range of $ Adds volume and VS to GHG poten=al Revenue poten=al

16 Scrape to Solids Scenarios - Costs

17 Solids Separa2on (Prior to Lagoon) Current industry adop=on not well documented Only simple mechanical separators es=mated here ~11% reduc=on in baseline GHGs

18 Alterna2ve Mgmt. GHG Mi2ga2on? Various Sep. Technologies Less certainty in applicability, economics, and impacts Possible increases in other emissions May be imprac2cal to implement in many loca2ons Aera=on, Acidifica=on, Straw Covers Weeping Walls

19 Summary A diversity of mi2ga2on prac2ces will likely be needed to achieve significant reduc2ons Small scale solu2ons may differ from large Need to work from both ends of the cow Significant investments will be required but cobenefits may exist Poten2al trade-offs on animal health and produc2vity, air-quality, water-quality, crop management, nutrient efficiency and costs should con2nue to be analyzed Addi2onal benchmarking and innova2on in manure processing and fer2lizer or co-product op2miza2on is needed