Greenhouse gas emissions and biogas potential from livestock in Ecuador

Greenhouse gas emissions inventories provide a baseline to develop mitigation projects for reducing emissions. However, a detailed inventory of livestock gas emissions is not available for Ecuador. This study attempts to fill this gap. The methodology selected comes from the 2006 Intergovernmental Panel on Climate Change guidelines to quantify emissions from the livestock sector. Tier 1 methodology was implemented using animal census data for the year 2000, and historical temperature data by province. The total methane emissions from enteric fermentation were 5596 GgCO2Eq. Methane emissions from manure came mainly from cattle and swine with 92.4 and 44.3 GgCO2Eq, respectively, and a livestock total of 182 GgCO2Eq. The total direct nitrous oxide (N2O) emissions from manure management were 172 GgCO2Eq, and total direct and indirect N2O emissions from manure deposited on soils by grazing livestock were 2176 GgCO2Eq. A further 103 GgCO2Eq of direct N2O emissions came from the application of confined-livestock manure to soils. We estimated the total potential reductions in emissions from capturing methane gas from anaerobic digestion of dairy, swine and poultry manure and substituting methane for liquefied petroleum gas (LPG) at 308 GgCO2Eq. The value of the methane produced could amount to US$ 77 M. Alternatively, that same methane gas could be used to generate 275 GWh of electricity. Additional benefits from anaerobic digestion of manure include the recovery of nutrients from the digested effluent, which could be used as biofertilizer and soil amendment. The capture of these greenhouse gases and the use of anaerobic digesters to produce energy and other products seem to have potential in Ecuador. However, lack of experience with anaerobic digestion and biogas production is a great limitation for the implementation of this technology. Also, anaerobic digester designs should be evaluated and modified to fit local needs given the variability of climatic and socio-economic conditions across the country.