Landfill Gas By Shawn Laumann

Landfill Gas: What is it? Generated by decomposition of organic material at a landfill site Mixture of gases, mostly methane (approximately 40-60%) and carbon dioxide Trace amounts of oxygen, ammonia, hydrogen sulfide and nitrogen

Landfill Gas: Negative effects If released into atmosphere, contributes to GHG emissions – One tonne of methane = GHG effect of 23 tonnes of carbon dioxide Gives off a disagreeable odor May result in health consequences from toxic and carcinogenic substance traces Increase risk of explosion at landfill if buildup occurs How do we minimize these effects??

Landfill: Parts A. Ground Water B. Compacted Clay C. Plastic Liner D. Leachate Collection Pipe E. Geotextile Mat F. Gravel G. Drainage Layer H. Soil Layer I. Old Cell J. New Cell K. Leachate Pond

Landfill: Parts Bottom liner system – Prevents trash from contacting outside soil, particularly groundwater Cells – Where trash is stored and compacted Storm Water Drainage – Collects rainwater that falls on landfill Leachate Collection System – Collects water that has percolated through landfill and contains toxic substances Methane Collection system – Collects methane gas formed during breakdown of trash Covering or Cap – Seals off top of landfill

Methane Collection System LFG extraction system comprises one or more wellheads Pipes are embedded within the landfill to collect the gas Wellheads are connected by the piping and coupled to a vacuum source that moves LFG from wellheads to a storage container Need to optimize vacuum so that methane content is within a reasonable range

Methane Collection System Methane Collection Pipe

Methane Collection System 1. Extracting Pipe Network 2. Control Valve 3. LFG Collection well 4. Liner of Landfill 5. Low Permeability Cap Layer 6. LFG Treatment System Vertical Extraction System

Methane Collection System The cap of the landfill does not seal perfectly, thus creating a pressure gradient Since air is mixing with the LFG, it is important to optimize the depth so that LFG utilization and treatment is at a minimal – Need a certain methane content, usually 45-55% methane

Captured LFG…Now What? Use a Methane flare for burning the gas – Converts Methane into carbon dioxide under controlled conditions Or, use it as an energy source Methane Flare

Landfill Gas: Energy Source In 1994, EPA created Landfill Methane Outreach Program Since the program was started, landfill methane emissions have been reduced by over 24 million metric tonnes of carbon equivalent This is equivalent to removing the annual emissions from 17 million vehicles

Landfill Gas: Energy Source Two common uses – Electricity generation Running engines or turbines – Combustion as an alternative fuel Cheaper than using natural gas

Electricity Generation LFG is burned in boilers, reciprocating engines, and combustion turbines to produce energy Advantages: – Directly reduces greenhouse gas emissions – Reduces air pollution by offsetting use of non- renewable resources – Improves air quality – Destroys non-methane organic compounds – Benefits local economy

Landfill Gas EPA estimated cost of generating power from LFG: – between 4 and 7 cents/kWh Cost of electricity: – cents/kWh

Landfill Gas Pretreatment – Used for de-watering and particulate removal – Also aimed at removing percentages of volatile compounds in the gas After pretreatment, the gas is ready for use

Landfill Gas vs. non-renewable energy Environmental impact of burning landfill gas – Produces nitrogen oxide emissions – Carbon dioxide produced from burning is considered to be offset by not using non- renewable energy sources – Require small amounts of water – Do not create large amounts of solid waste – Has little impact on land resources

Landfill Gas vs. non-renewable energy Natural Gas: – Extraction of natural gas and construction of natural gas power plants destroy natural habitats for plants and animals – Also result in erosion, loss of soil productivity, and landslides Coal – Contaminates soil and coal mining has environmental impacts on land

City of Fargo and Cargill LFG Energy Project Problem before project: – Close proximity of residents to landfill Odors created from landfill operation needed to be reduced Solution: – City installed LFG collection and flare system Cargill recognized energy potential and approached city about using LFG for their boilers – Developed a direct-use landfill gas energy project – City of Fargo installed LFG collection system – Cargill and City split cost of 1.5 mile pipeline – Cargill installed dual fuel burners and new control system

City of Fargo and Cargill LFG Energy Project Project highlights: – Generated revenue for City of Fargo and reduces Cargill’s energy costs, emissions, and dependence on natural gas – Reduced the landfill odor emissions Environmental benefits: – Annual GHG reductions equivalent to removing the emissions of 9,100 vehicles – Annual energy savings equate to powering 3,000 homes

Landfill Gas Why is this important? Out of 2,300 currently operating or recently closed landfills (in the US), only 400 have LFG utilization processes It is estimated 560 more will have LFG utilization processes in the future, reducing the GHG effect equivalent to removing the emissions of 11 million vehicles 1,300 landfills will be doing nothing Municipal solid waste landfills are the largest human- generated source of methane emissions in the US More companies need to use LFG to decrease emissions and to save money on energy costs More landfills need to either use the LFG as energy or install a Flare

Landfill Gas Why aren’t more landfills being utilized like in the Cargill and City of Fargo case? Not all landfills are close to companies Not all companies are aware of landfill gas and its advantages for energy use The Landfill owner will not spend money unless it has to Some landfills are not big enough Some people do not consider LFG as Green energy

Landfill Gas What is green energy? Energy produced from clean (low-emitting) energy sources Energy that is used in ways that produce less air pollution Is landfill gas green energy??

Resources ent_tech.pdf ent_tech.pdf landfill-gas-extraction-system-dt ptan php landfill-gas-extraction-system-dt ptan php