Brits Seeking a “Huge Increase” in Anaerobic Digestion

The UK’s new government is aiming for a “huge increase” in anaerobic digestion, requiring “two plants built each week over the next ten years” estimates the Anaerobic Digestion and Biogas Association (ADBA).

Framing their efforts as part of a larger “war on waste”, the Tory/Lib-Dem Anaerobic Digestion (AD) plan includes the collection of thousands of tons of food waste, which will serve as feedstock for new anaerobic digestion plants such as the Selby Renewable Energy Park we reported on in May.

Why would the new Tory-led government favor anaerobic digestion?

As an island nation, England is a nation of port cities who go to considerable expense to transport their waste inland. Food waste takes up 15-20% of the municipal waste stream, and yard waste, 5% of it.  Instead of being transported to landfills, this waste can be a valuable resource, and can be put to its highest and best use: anaerobic digestion and composting.  The government recognizes this opportunity and is putting these resources to work.

Also, as a participant in agreements such as the Kyoto Protocol, Britain is aiming at reducing its greenhouse gas emissions. Anaerobic digestion has the potential to contribute to that effort. According to the Chicago Climate Exchange draft guidelines, a single ton of food waste will emit .872 metric tons of CO2 equivalent over 10 years (this is assuming a GHG capture effort after 3 years). This makes AD a hugely attractive alternative energy. Even factoring in the emissions of waste transportation (about 6 kg per ton when trucked 25 miles), and the emissions resulting from combusting the resulting biogas (about 280 kg of CO2 for each ton), the saved CO2 equivalent is still .580 tonnes for each ton digested and combusted rather than landfilled.

Lastly, AD is the rare renewable energy that provides a consistent baseline load (unlike wind or solar, which are much more variable), making AD a sensible early component of a robust portfolio of renewable power. Moving forward in a world with limited environmental and economic resources, we need everyone at the table, including AD.  To learn more about the vision for 1,000 biogas plants by 2020, check out the ADBA website, or attend their conference July 7-8, 2010.

The Debate Over the Highest and Best Use of Organics

By Elizabeth Lowell

Recently, there has been a lot of debate over organics in the landfills and a landfill’s role in generating energy in the form of landfill gas. Today’s landfills are constructed as sanitary landfills, meaning they have a liner and they are sealed with a cap when full. The material disposed into them is compacted very, very tightly. In practice, this turns landfills into great big anaerobic digesters that produce a form of biogas with around 50% methane content.  The amount of electricity a landfill can generate and its emissions of greenhouse gas emissions are determined by its landfill gas capture efficiency. Just like at wastewater treatment plants, dairy farms, and high solids anaerobic digesters, in landfills the greatest producer of biogas is organic waste like yard clippings and food scraps.

Here is the debate: Should organics be dumped in landfills that capture biogas and generate energy? Or should they be diverted, even banned, from landfills and sent to composting, and increasingly anaerobic digestion, facilities?

BioCycle Magazine’s May 2010 issue was titled Putting the Landfill Energy Myth to Rest and included a 12-page article covering everything from gas generation and decomposition rates at landfills to the nutrient content in organic waste and various organic processing technologies. A complimentary PDF of the article may be downloaded from BioCycle: http://www.jgpress.com/1005_lem/bc1005lem.html. Days after the article hit the presses, Florida Governor Charlie Crist vetoed a bill that would have overturned a state ban on disposal of leaves and other yard waste in landfills. In his letter to the state legislature explaining his veto, the Governor stated, “Although the bill requires landfills to capture and make beneficial use of methane gas to qualify to accept yard trash, it directs materials to landfills that would otherwise be recycled.” The legislature has recently set a 75% recycling goal for the state. Read more on Governor Crist’s veto at Waste & Recycling News or at Harvest Power’s blog here or here.

During the same month that BioCycle issued its report, SWANA (the Solid Waste Association of North America) approved a statement concluding that a report entitled The Importance of Landfill Gas Capture and Utilization in the U.S. “presents a valid representation of the state-of-the-art of landfill gas capture and recovery as practiced in the U.S.” SWANA went further, endorsing certain conclusions of the report as being “fully consistent with [the organization’s] mission and policies.” To read more about SWANA’s position, click here.

The Landfill Gas Capture and Utilization report details the efficiency of gas generation and capture, noting that efficiency varies from landfill to landfill based on when the capture system is put in place, the content of the waste stream the landfill receives, and many other factors. It also discusses the lower capital costs associated with gas capture systems (though it does not include an analysis of the capital and operating expenses of landfills, which serve as the gas producer), and carbon reduction credits associated with composting versus landfill gas, focusing on detectable emissions from composting operations while acknowledging that these vary greatly by facility and are substantially decreased by well-run operations.

The report, while lengthy and thorough, neglects to mention the numerous beneficial properties of compost.  Compost and compost-based soil products add nutrients, improve soil structure, aid in water retention, reduce erosion, and enhance plant growth. Compost-based soil products also offer an alternative to petro- and chemical-based fertilizers. A landfill gas capture system, no matter how efficient, will never produce compost.

These are just two of many articles and discussions on the topic. The debate continues.  We can put organic waste in landfills and produce energy.  We can put organic waste in composting facilities and benefit from the resulting compost. We can create renewable energy and high quality compost from organic waste through anaerobic digestion and composting. So what is the highest and best use (in terms of economics, efficiency, and environmental impacts/benefits) of organic waste? At Harvest, our money is on energy and compost.

Renewable Energy from The Big Apple

By: Sameer Rashid

Did you read the Op-Ed the other day called ‘Power from Trash‘ in the New York Times?  Using our waste in a more productive way seems to be a popular theme in the news and editorial pages this year.

New York City has been my home since 2001 and I’ve also been working hard on developing an organics recycling and biogas plant in the area, so I wanted to highlight a few important points from the ‘Power from Trash’ article:

“…As New York City’s garbage decomposes, it releases some 1.2 million metric tons a year of carbon dioxide and its equivalents — primarily methane — into the atmosphere. On top of that, the fuel it takes to haul 11,000 tons of waste hundreds of miles six days a week releases an additional 55,000 tons of greenhouse gas per year…”

“…Since New York began exporting its garbage, the Sanitation Department’s budget has more than doubled, to $1.3 billion in the current fiscal year from less than $600 million in 1997. And in the past seven years, the costs of the city’s landfill contracts have gone up more than $90 million, enough to pay 1,000 full-time firefighters, nurses or teachers….”

“…If all of the city’s nonrecycled waste were sent to local energy recovery facilities instead of distant landfills, the city would save diesel fuel and generate enough energy to supply 145,000 homes — thus avoiding the combustion of nearly three million barrels of oil to generate electricity….”

“…Newer kinds of facilities — like those that use anaerobic digestion to make methane — could be built on smaller sites…”

There were a lot of good points in the article and I couldn’t agree more with the last two quotes highlighted above.  Local facilities that utilize commercialized high solids anaerobic digestion (HSAD) technology to produce renewable energy and compost is in some ways a no-brainer for New York City and other major metropolitan areas in the country.  In addition to maintaining Harvest’s high standards, we can address issues like siting and community support by co-locating with existing transfer stations, water treatment plants, and/or compost facilities in the City and improving those facilities’ environmental footprints.  With the amount of food waste generating by New York’s restaurants, markets, and food processors, HSAD represents a tremendous opportunity to save thousands of small businesses money and simultaneously make them more sustainable.

Sameer Rashid, an avid fan of all things New York (especially the Mets), develops projects throughout the East Coast, and loves to talk food waste.

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