Today the word "incineration" means much more than just burning trash in a corner of the back yard. Incineration with energy recovery has become the waste disposal method of choice in several European countries where it is actually classified as a Renewable Energy Source, making it eligible for tax credits. Even in the United States electricity generation by incineration plants is eligible for a Renewable Energy Production Incentive (REPI) of 0.9¢ per kilowatt-hour (kWh) generated. Incineration currently has a nationwide operating capacity of 95,000 tons per day. So, should you embrace incineration and welcome it into your community? Arguments In Favor Of Municipal Solid Waste (MSW) Incineration
In 2008 the United States generated 250 million tons of MSW, of which 33.2% was recovered (recycled or composted), and 12.6% was incinerated, leaving 135 million tons to be sent to landfill facilities. With an expected generating efficiency of 665 kWh per ton of MSW we are potentially discarding 90 terawatt-hours (90,000,000,000 kWh) each year, enough to power over 8 million average US Households.
Electricity generated from MSW incineration comes with an environmental cost of about one ton of carbon dioxide emissions per ton of MSW (or 1.5 kg per kWh). While this is more than the emissions from most conventional electricity generation it does come from renewable sources. Since most of the organic materials in MSW come from biogenic sources it can be said to have a low net carbon contribution to the atmosphere because previously removed CO2 is just being returned to the atmosphere. More importantly, the incineration of MSW eliminates the same amount of carbon being emitted from a landfill in the form of CH4 (methane), which has 23 times the global warming impact of CO2.
Arguments Against Municipal Solid Waste (MSW) Incineration
The primary argument against incineration has been surrounding its emissions. The incomplete combustion of certain materials can result in the creation of potent greenhouse gases methane (CH4) and nitrous oxide (N2O) but also particulate matter emissions and gases that affect local air quality such as SOx and NOx. What's worse are the byproducts from the incineration of materials containing heavy metals and other harmful substances, which include dioxins and furans. While careful screening of feedstock and high incineration temperatures can greatly reduce these worrisome emissions, some people are still concerned. Finally, while incineration greatly reduces the volume of landfill waste (~95%), the ash that remains can be toxic and require special disposal facilities.
Other Technologies On The Horizon
One emerging technology in the field of waste incineration is plasma arc where an electric arc creates extremely high temperatures (25,000°F) that gasify waste, creating a "syngas" that can be used to generate electricity or to create liquid fuels. Plasma arc technology helps to address some of the emission concerns of incinerationbut it is less efficient at creating electricity and the technology is still more costly.
On a recent trip to Finland I had the opportunity to visit a biomass gasification demonstration facility operated by Preseco. In this facility the biomass waste from the forestry industry was turned into syngas and biochar through the process of pyrolysis. The implication of this technology is exciting, especially for agricultural and other biogenic waste materials that would otherwise decay.
Pablo Päster is a weekly columnist for TreeHugger.com, an experienced greenhouse gas engineer and the Senior Environmental Program Manager at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
More TreeHugger Articles On Waste Incineration:
Waste To Energy
Are Local Incinerators Just a Load Of Hot Air?
Dubious Waste-to-Energy Incinerator Project to Put Delhi Waste Pickers Out of Business