Most LFG energy projects in the United States generate electricity; in aggregate such projects generate almost 1000 MW of green power. Little or no effort is made to clean LFG before combustion in the engine, and evidence has accumulated that untreated LFG fuel degrades engine performance compared to operation with natural gas.
Problems include up to 50% reduction in engine head life, valve guttering, unbalanced turbines and turbo chargers, and spark plug fouling. The consequences are increased maintenance, increased engine emissions, premature equipment failure, and excessive project downtime.
Most of these problems are caused by siloxane trace contaminants in LFG.
Siloxanes are commercially produced compounds and are used in a wide variety of applications such as adhesives and sealants and personal care products.
Combusted siloxane compounds form hard sand-like deposits (silicon dioxide) which accumulate on rotor blades, spark plugs and other engine parts and cause various engine problems. Pictured below are silicon dioxide deposits on engine parts exposed to landfill gas combustion products.
CO2 Wash® removes siloxane contaminants from LFG to below detection limit of 5ppb (parts per billion).
Electric generation projects, new and existing, benefit from CO2 Wash®:
Processing steps required to convert LFG to Electricity with CO2 Wash® are shown below.
- Electric power generation economics improve due to lower engine maintenance, and sale of recovered liquid CO2,
- Better economics create the opportunity to utilize smaller landfills for electric generation.
- Electric power generation with clean landfill gas fuel allows use of NOx control technologies such as selective catalytic reduction (SCR) to reduce NOx emissions and permits renewable energy recovery in areas of restricted NOx emissions.
- Clean landfill gas fuel affords opportunity to consider fuel cells in the development of new landfill gas electric projects.
- Biomass CO2 recovery and sale lowers net emission of CO2 to atmosphere, and offers commercial and industrial consumers a reliable local source of CO2.
Acrion Technologies, Inc.