American Recycler, April 2010 | Small landfills hold big potential

Regulatory pressure is building on those sources emitting greenhouse gas (GHG), especially landfills, particularly under the proposed EPA Tailoring Rule. If enacted, many small and medium sized landfills will become major sources and subject to New Source Review under EPA’s Prevention of Significant Deterioration (PSD) and Non-attainment New Source Review programs if they expand existing operations, and will be required to obtain Title V operating permits if they do not already operate under one. Besides heavy costs for compliance, it may lead to government mandated remediation and unfunded costs.

Concurrently, the waste industry is fighting hard to exempt landfills from these new regulations because unlike industrial combustion emissions, landfill gas (LFG) is uniquely different – a naturally generated gas, predominately methane, produced by organic decomposition. It’s ironic that when America is crying for energy independence and scurrying to bring more renewable energy to the grid, that landfill gas recovery has taken a national backseat to solar and wind generation, especially when you take a close look at the comparative economics.

While solar and wind are non-polluting energy sources, they do not stand on their own economically and owe their proliferation to rebates and tax incentives. The fact that they are clean may justify public investment, but without generous subsidies, not many private investors in the States would put up a dime.

On the other hand, a well engineered LFG recovery and power generation system can pay its own way, return capital investment in three to five years and continue to earn profits for decades, even without carbon credits and tax deductions that can add to profitability. By doing so, GHG emissions from landfills can be converted to energy and be added to the mix of renewables in utility portfolios.

Barry Rogers, general manager of LFG Technologies, has been converting landfill gas into energy and installing low-emission enclosed flares for over 25-years. His company designs, specifies, procures equipment, constructs and starts landfill gas-to-energy projects. Rogers works with landfills that have engineered and installed a piped recovery system and then engineers and delivers turnkey projects to a performance standard.

A pioneer in this business, LFG Technologies has built over 50 landfill gas recovery projects, producing over 150 megawatts of electricity. From a GHG emissions standpoint, these projects daily consume billions of cubic feet of landfill gas. Rogers provided insight into the challenges. “Our primary focus is doing something with the gas once it is recovered, create an energy source and either put it in a pipeline or into an electrical line. The majority of our work has been in working with utilities to create electricity and put it into the grid.”

Environmental zealots will argue that LFG is not green enough and should not qualify as a renewable energy source because they characterize it is as a dirtier form of natural gas, which does not qualify for renewable energy tax credits. LFG is approximately 50 percent methane with the remainder mostly carbon dioxide (CO2). It also contains nitrogen, oxygen, water vapor, sulfur and contaminants, most being non-methane organic compounds (NMOC), but these minor constituents usually constitute less than 1 percent of LFG. Nevertheless, LFG qualifies as renewable under the federal Production Tax Credit (PTC) in the same category as hydroelectric, biomass and the conversion of solid waste to energy.

The options for handling LFG are limited. It can rise into the atmosphere and add to other greenhouse gases that many see contributing to global warming or climate change. For larger landfills, EPA regulations require collected landfill gases be sent to a control device (including flaring-off the gas – thermally oxidizing gas) capable of achieving a better than 98 percent destruction efficiency.

Storing LFG is not practical unless you clean it and convert it to liquid natural gas (LNG) which limits it to typically larger landfills. Burning volatile organics to destroy them seems an obvious waste of energy albeit necessary if no alternatives to beneficially use it are available. Burning the gas to heat water or boil it to create steam for use in steam turbine power generation has limited application. Cleaning LFG so it is non-corrosive enough to put in a pipeline for end use combustion is expensive and often impractical unless near a pipeline and a user that wants it.

A more practical, universal way to monetize LFG, particularly for small and medium sized landfills is by pre-combustion cleaning and treatment of the gas and using it as fuel to power either turbines or reciprocating engines to generate electricity.

Rogers confirmed this popular option. “Our business has been growing substantially. 2009 was our busiest year to date and 2010 is expected to be better. The primary reason is we don’t work with landfills, rather 100 percent with utility companies. Their driving force is to purchase a certain percentage of their output from renewable sources to meet portfolio objectives set by public utility commissions.”

Rogers is very busy now only because methane recovery systems take several years to develop. “Unless the economy turns around, we are probably going to see a slowdown in our business due to low natural gas prices and lower demand for energy.”

LFG to electric generation make sense for several reasons. Generation equipment can be scaled down to very small landfills, or modularly scaled up with additional engines or turbines as landfill gas flows increase, either due to landfill expansions or unexpected higher flows. A flow of only 300 standard cubic feet per minute (SCFM) with 50 percent methane can generate 800 kW of electricity. LFG Technologies, for example, has a few small projects. One at 300 SCFM consistently produces 600 kW per hour and unlike wind or solar runs ‘round the clock. While systems can be as large as 40 megawatts, most are in the three to five megawatt range.

How long will a landfill continue to generate methane to make electricity? According to Mike Niemann, landfill gas program technical director for Environmental Information Logistics, a consulting firm to major private landfills operators and municipalities, “From an environmental standpoint, methane will be continually produced for 20 to 70 years or more while landfilled organic material decomposes. For economic viability you are realistically looking at 30 to 40 years. I’ve been working on some facilities that have been beneficially recovering landfill gas for over 20-years and are still going strong despite the landfill being closed.”

Surprisingly, not all landfills tapped for methane have diminished flow over time. LFG Technologies uses planning tools, but mostly relies on experience to evaluate the economic viability of LFG to energy projects. “There are so many variable factors we have to be extremely conservative in our estimates. Because of the risk structure you have to be able to recover your investment in 5-years,” he emphasized. “It’s always easy to expand the equipment.”

EPA regulations are somewhat elastic, have opt-outs and loopholes when it comes to mandating when an aggregate gas collection and control system must be installed in a landfill, but generally the tipping point is anywhere from having two to two and one-half million tons of solid waste in place.

“EPA does provide various control options, but several thousand landfills flare-off the gas to some degree or another. It’s the most predominate and cheapest form of control,” said Niemann. Once mandated, however, the landfill is unable to claim carbon credits or trade them because the carbon offset market is based on voluntary emission reductions. However, if the landfill uses LFG to generate electricity they may be eligible for IRS Section 45 tax credits at $10 per megawatt hour, and perhaps renewable energy credits (RECs) depending on state and region where the landfill is located.

“Given that there are over 7000 landfills in the United States and only about 500 energy recovery facilities, the potential is quite large, but economics play a big role in the development of viable projects at smaller facilities. Capital expenditures can be quite large and once a landfill closes its potential gas production declines. Micro turbines have been shown to be reliable, but they still are expensive,” said Niemann. That’s why LFG Technologies usually recommends reciprocating engines to generate power rather than turbines. The capital cost is much lower and payback more assured.

EPA’s Landfill Methane Outreach Program (LMOP) currently lists only 509 operational projects generating 1,563 megawatts of electricity and 304 million standard cubic feet of gas per day (MMSCFD). They also list 530 landfill candidates with the potential to produce 1,170 megawatts and 15.5 MMSCFD. There’s huge opportunity for greater gas to energy projects. Private investment and development companies are willing to front the capital costs to build systems in return for the carbon credits and a share in the ongoing electric production, even for small and medium sized landfills.

“Whether flaring it or combusting it in an engine to generate electricity, you eliminates greenhouse gases. You change it into other compounds that are different, but you eliminate volatile organics from going into the air,” said Rogers.

The Law of Conversations of Mass states that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products. It’s all going someplace anyway. There is no perfect way to handle greenhouse gas emissions from landfills, but as long as EPA regulations lead to flaring-off the methane, landfills may as well productively use that energy to generate electricity.