Wednesday, June 13, 2007

No Longer A Waste: Energy and Recycling

The Economist had a recent article on municipal curbside recycling which laid to rest the question of whether recycling is good for the environment. Recycling involves trucks, other machinery and energy inputs, so a valid question is whether or not the amount of materials extracted justifies the amount of energy used in the process. Using the results from a recent study sponsored by the UK-based Waste & Resources Action Programme, the answer is recycling DEFINITELY pays off. The study is essentially a meta-analysis of about 55 respected Life Cycle Analyses from several countries.
The UK’s current recycling of those materials saves between 10-15 million tonnes of CO2 equivalents per year compared to applying the current mix of landfill and incineration with energy recovery to the same materials. This is equivalent to about 10% of the annual CO2 emissions from the transport sector, and equates to taking 3.5 million cars off UK roads. ... The message for policy makers and practitioners is unequivocal. Recycling is good for the environment, saves energy, reduces raw material extraction and combats climate change.
The article also includes interesting factoids, along with several graphs and metrics.

The above graph is based on data from the OECD. Recycling Rates are defined to be the total (weight in tons) of all Recycled Municipal Solid Waste (MSW) as a percentage of Total MSW. In recent years, single-stream or co-mingled recycling has been used successfully to boost recycling rates. In single-stream recycling, a single recycling bin is provided and materials are separated by the recycling facilities. With an extremely high recycling rate of 69%, San Francisco is one of the most successful single-stream recyclers around. Through a combination of human and machine-automated separation techniques (Eddy-current separators), SF "... processes an average of 750 tons of paper, plastic, glass and metals a day."

I used the colorfully titled 2006 State of Garbage in America to get a snapshot of the recycling rates by state. As a secondary metric, I will also look at the percentage of total MSW (municipal solid waste) which ends up in landfills. Using this metric, the Rocky Mountain Region performed horribly, with 86% of all MSW ending up in landfills:

In New England, 36% of MSW is converted to energy thus only 35% of total MSW ends up in landfills. After recyclable materials are separated, the remaining suitable MSW are combusted and the heat generated is used to power steam turbines that generate electricity. In a previous post, I compared sources of electricity for a few key countries and noted that Denmark generates 3.6% of its electricity using MSW. These Waste-to-Energy facilities do create emissions, but the EPA considers the emissions from these primarily biomass derived materials, to be part of the "Earth's natural carbon cycle". Because of the variation in Waste-to-Energy facilities, there are possibly other environmental problems that accompany such facilities.

I loaded the data and mapped the results at the State level. For recycling rates, higher rates are desirable. The West Coast states (CA, OR, WA) all recycled at least 40% of their total MSW:

I'm astounded that in the year 2006, there are still states with single-digit recycling rates!

For the percentage of total of MSW which ends up in landfills, lower rates are desirable. The New England States convert a large percentage of their MSW to energy so they have lower percentages ending up in landfills:

CT converted a whopping 65% of its MSW to energy! To the extent that the low Landfill rates are driven by high Waste-to-Energy conversion rates, further studies on the environmental impact of such facilities should be conducted.

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