The Trash Blog

Roosevelt Landfill Gas-to-Energy Facility

When organic waste ends up in a landfill, it will inevitably produce landfill gas (LFG is roughly 50% methane and 50% carbon dioxide). However, what happens to that gas varies greatly. Though most landfills have some gas collection infrastructure (functioning at various degrees of efficiency), nearly 80% of the time collected gas is simply be flared off. However, of approximately 2,400 landfills in the US, about 500 have some type of LFGTE (landfill gas-to-energy) system. This means that the landfill has a series of wells  and pipes dug through it to capture the LFG and bring it to a power plant for conversion to energy.  Estimates suggest that such systems can capture 60-90% of LFG. In 2011 it is estimated that these systems together produced more than 15 million kWh.

This photo, taken at WM's Cedar Ridge landfill, shows some LFG collection pipes.

This photo, taken at WM’s Cedar Ridge landfill, shows some typical LFG collection pipes.

Art Mains, Roosevelt's Environmental Manager, was kind enough to offer us a tour of the site.

Art Mains, Roosevelt’s Environmental Manager, was kind enough to offer us a tour of the site.

We visited one such gas-to-energy project at the Roosevelt Regional Landfill in Klickitat County, WA. Roosevelt, operated by Republic Services, was one of the first landfills in the US to capture LFG, and remains one of the largest projects of its type. The landfill receives ~2.5 million tons of waste per year from across the Northwest, and produces 21 megawatts of energy annually from this garbage at its onsite H.W. Hill Landfill Gas to Energy Project. The energy produced can power between 7,000 and 20,000 homes, depending on which estimate you read and the energy emitted at any one time. As the landfill grows, this capacity may also grow, and Republic Services estimates that future capacity may power as many as 30,000 homes.

IMG_6074

H.W. Hill is actually a combined cycle, or cogeneration, facility. The LFG is used to both generate electricity and thermal energy. I had a very embarrassing experience while photographing this enormous fan involving my skirt… I won’t go on.

The landfill includes a lechate recycling system, whereby lechate from the landfill is collected and poured back into the landfill. This is meant to speed up anaerobic decomposition, increasing gas output.

The EPA appears to be a major supporter of LFGTE projects as a source of ‘green energy’ and began its Landfill Methane Outreach Program (LMOP) in 1994. The EPA states that it “launched LMOP to encourage productive use of this resource as part of the United States’ commitment to reduce greenhouse gas emissions.”

But how do we define a ‘green’ or ‘renewable’ energy source? There is a major debate surrounding the classification of landfill gas-to-energy projects as ‘green.’ I’ll save this for a future post, but for now, consider a few things:

– To be effective, the smallest LFGTE project needs to receive at least half a million tons of MSW a year, which may result in an incentive to send organic materials to landfills. This may have something to do with the fact that there have recently been a number of cases in which Waste Management (the #1 waste company in the US) has worked to overturn several state bans on sending organics to the landfill.

– According to University of Washington professor Sally Brown, anaerobic digesters could capture significantly more gas from organics than landfill gas-to-energy systems, increasing the energy production potential significantly. So, if we are to take this energy source seriously as a ‘green’ energy alternative, do landfill capture systems make the most sense?

– LFGTE projects are said to ‘offset’ CO2 emissions. The Klickitat County Public Utility District writes that, over its 80 year lifespan, H.W. Hill will offset  35.4 million tons of CO2. But these figures are based on the CO2 that would be emitted from burning coal to produce the equivalent energy. These figures are a little bit misleading because they assume that the coal will be burned anyway.

Food for thought!

Advertisements
This entry was written by Margaret and published on May 20, 2013 at 9:37 pm. It’s filed under Energy, Landfills, Methane, MSW, Organics and tagged , , , , . Bookmark the permalink. Follow any comments here with the RSS feed for this post.

6 thoughts on “Roosevelt Landfill Gas-to-Energy Facility

  1. Uncle Chris on said:

    Quantitative analysis is good! Maybe you two will come up with a system that evaluates the “green” effect of certain recycling or energy conversion programs associated with trash. For example, does it take more diesel fuel to collect the organic matter than the organic matter in the landfill can produce in terms of energy? Would this amount of diesel fuel be expended anyway, so that any produced energy is a bonus? . . and so on. . . .

    Hope you guys are well . . . and safe!

  2. There is a technical problem with LFG that as yet, has not been solved. It is a matter of “conditioning” the LFG to burn cleanly. LFG as you might expect, is full of contaminants(heavy metals, etc.). Turbines, the equipment typically used to produce energy from gas, do not like contaminants. They are easily damaged by such byproducts. Typically, these contaminants have to first be removed from the gas. There isn’t a real good, cost-effective method for conditioning LFG yet.

  3. Diana on said:

    This seems like a good initiative (anything that reduces greenhouse gas emissions is a good initiative) however, how affordable are these projects? How can this be considered a renewable source of energy of if the source is not renewable?
    Keep up the excellent work! Abrazos grandotes!

  4. Pingback: Landfill Afterlives | The Trash Blog

  5. Pingback: Harvest Power | The Trash Blog

  6. Pingback: Is Landfill Gas Renewable? | The Trash Blog

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: