EM technology, Biodigesters and Biogas

Methane 20 times more GWP than carbon dioxide Anthropogenic sources Agriculture Domestic animals From 1750 to 2000, methane increased in atmosphere from 700 ppb to 1800 ppb

Biodigesters: what and where A biodigester is a biogas generator where anaerobic decomposition of organic waste occurs Work best in warm climates- optimum ~35 degrees C Biogas is a mixture of gasses resulting from material breakdown Heating power of 4500 to 6500 kcal per cu m 1 cu m of biogas is equivalent to o.6 liters of gasoline and.5 liters of kerosine

Stages of EM digestion Stage 1: hydrolysis Bacteria break down organic molecules Stage 2: acidification Monomers are acidified Stage 3: methanization Methane is produced when bacteria break down acids Optimum: 35 degrees C, 6-7 pH Satisfactory gas production can take place at 25 degrees C, but below about 10 production effectively stops

Annual methane emissions from agriculture

calculations How much energy we could get from cow and pig manure? 19.5 billion tons of cow manure produced worldwide each year 30.5 quadrillion Btu per year potential methane from cow manure 5.9 million tons of pig manure produced worldwide each year 1.37 quadrillion Btu per year potential methane from pig manure

Where biodigesters are most important India’s population is increasing rapidly China’s people are seeking higher levels of wealth – pigs are increasingly wanted Both countries have already implemented millions of biodigesters

Sustainability Energy yield from methane would have a minimal impact, but other factors make biodigesters worthwhile investments Relative costs Replacement for coal? Health issues Biogas is similar to natural gas But- renewable and less prone to costly extraction and leakage problems Biogas would provide affordable heat and electricity and reduce emissions related to dirty fuels by replacing them Germany predicts they can produce enough biogas by 2020 to replace all of Russian natural gas imports

Conclusions Ambiguous long-term and global effects Yield from worldwide manure amounts would be 6% of projected worldwide energy use in 2010 For more information, consult our web page at

Thanks to the members of the Earth Institute of Costa Rica for their help