Traditional energy resources may be on the wane, but landfills are actively producing supplies by the minute across the country.

By Jim Logan

As this is written, oil has gone over $50 a barrel, natural gas has climbed to over $7 per MMBtu, and climatologists say greenhouse gases—namely methane and carbon dioxide—continue to exacerbate global warming. Meanwhile, at least a partial solution to these problems, the use of landfill gas (LFG), grows by the minute in hundreds of sites across the country.

That collecting and using LFG can offset fossil fuel consumption and keep millions of tons of greenhouse gases out of the atmosphere is a given. More than 350 landfill gas-to-energy (LFGTE) projects in 40 states are doing just that, according to the EPA’s Landfill Methane Outreach Program (LMOP), which promotes the use of LFG as a renewable energy source.

With varying degrees of processing, LFG can be used to fuel diesel generators, gas turbines, and microturbines to replace fossil fuels at industrial sites, or as pipeline-quality gas. It can be processed into liquefied natural gas (LNG), compressed natural gas (CNG), or even converted to methanol, hydrogen, or virtually pure carbon dioxide (CO2). And, given that methane traps 21 times more heat than CO2, keeping it out of the atmosphere has enormous potential environmental benefits.

In some ways, however, LFGTE is a concept that’s only just now beginning to hit its stride. It’s been little more than a decade since scientists and landfill managers proved that LFG was a viable resource of vast potential, but the pace of innovation in collecting and processing it has been deliberate at best. According to a number of industry professionals and academics interviewed by MSW Management, the reasons are varied. But put everything in a petri dish and what grows is simple economics. In other words, innovation hasn’t paid—at least not yet. That’s changing, but we’ll get to that in a bit.

Beyond economics, advances have been slowed by the lack of a robust research and development (R&D) sector in the industry.

“The landfill and solid waste industry has not been a particularly research-intensive area,” says Don Augenstein, an LFGTE pioneer at IEM in Palo Alto, CA. “There are certainly people doing good work, advancing LFGTE technology but, overall, the amount of research is modest compared to levels of research in other energy areas, for example, fuel cells, photovoltaics, wind power or—for that matter—more energy-efficient lighting.”

A Young Industry
When you get down to it, the modern landfill is a relatively recent phenomenon, having evolved from a smelly hole in the ground or not-so-fragrant mounds of waste, all within the lifetime of many present industry professionals. Some areas, such as LFG collection, are using technologies that have changed little in the past two or three decades. It doesn’t mean they’re necessarily bad technologies; long experience has proven them adequate indeed.

“I’ve been in this landfill gas business now for almost 25 years; technology really has not changed,” says Richard DiGia, vice president of operations and construction for DTE Biomass Energy, the US leader in LFG recovery. “You still go in and drill vertical wells, typically when the landfill is at or near finish grade. We also add in a combination of horizontal wells in active landfills, so that we can collect gas as the landfill is being built. Also tapping into leachate cleanouts of the leachate collection system tends to trap gases that we can capture. But basically it’s still the same technology. There’s not a lot of variability from site to site other than the number of wells and maybe the configuration.”

DiGia says DTE operates as it has for a simple reason: it works. Doing something different without equal or better results wastes time and money.

“A lot of people have tried a lot of things,” DiGia says. “There was an international company … that came into the US several years ago. They kept telling us we were doing everything wrong, that we just needed to approach our gas collection differently. And they tried it on a number of sites here and didn’t meet with very much success. We’ve tried a lot of different things; it’s just still the same basic premise of drilling wells in the landfill and putting a vacuum on it and extracting the gas that’s generated.”

None of this should suggest that LFG collection and conversion to energy is in stasis. In fact, research in academia and industry holds the promise of significant advances in LFGTE technology and the coming commercialization of advanced conversion applications. It won’t happen tomorrow, and there are skeptics even within the industry, but with the price of fossil fuels still climbing and the growing awareness of the need to deal with LFG, innovation and acceptance are inevitable.

A Little Background
The modern landfill and the idea of turning LFG into energy are both roughly 30 years old—about the age of a fresh post-doctoral student. The former was born in the wake of the environmental movement, the federally mandated product of an understanding that unregulated dumping was not the best way to handle the nation’s waste.

“We’ve certainly in the past 30 years gone full circle on how we approach waste disposal,” says DiGia. “Initially, people used to go into wetlands, basically, and say, ‘What else am I going to do with this land? I’ll fill it with garbage.’ And so you had wet landfills, and then we figured out that, gee, those swamplands or wetlands recharge our aquifers and by putting garbage on top of it we’re now contaminating our aquifers.

“So we went full circle and said, let’s create dry tombs or really entomb the waste,” he continues. “We’ll put a liner on the bottom to protect groundwater, then we’ll put a liner on top so that we don’t create more leachate, which adds pressure to the bottom liner and potentially causes leaks. And then we figured out, well, if we entomb the waste … that mass is going to be biologically active for 50 or more years. Is that really a good thing? So now we’ve gone full circle and we say, ‘Let’s protect the groundwater, but let’s augment the decomposition by adding water and going into bioreactor mode and trying to create an inert mass as quickly as possible and at the same time capture all the gas that’s available.’ ”

The controlled landfill bioreactor is in part the brainchild of Augenstein, who was a junior engineer at Dynatech Corp. in 1976 when he published a paper titled “Fuel Gas Recovery From Controlled Landfilling of Municipal Waste.”

At the time, Consolidated Natural Gas had spent well over $1 million on vessel processes that, Augenstein says, “weren’t working. What had happened was that I said, ‘You know, the only really economic way out is to ferment a landfill.’ I came into this from left field, completely outside the normal waste management area. I did a master’s degree on transport processes in biological systems. So I worked things out. I said, ‘Is there any barrier to converting waste in landfills to methane in a much more controlled fashion?’ And we already knew conversion happens when rain falls on the landfill. I worked out the diffusion equations and, son of a gun, it didn’t look like there was any fundamental barrier to fermenting a landfill.” Lab tests confirmed that early supplemental liquid addition, over and above “leachate recycle” of any leachate that might be available, was one key to greatly accelerated methane generation.

Augenstein’s projections eventually were tested and demonstrated at a landfill in Mountain View, CA, with participation of others, including John Pacey and staff of EMCON. The LFGTE industry saw that control and substantial acceleration of landfill methane generation would be possible. But more on this shortly.

Fermenting Energy
LFG, of course, is a natural product of decomposing waste. All it takes is waste, an anaerobic environment, and water to create LFG, which consists of roughly 50% methane and 50% carbon dioxide. It’s a relatively simple process, but it presents a number of challenges in controlling and monitoring the generation of LFG—two areas that are the subject of promising research.

One of the most active research sites in the country is the Yolo County Central Landfill in Woodland, CA, where Ramin Yazdani has overseen a full-scale bioreactor project since 2001. Yazdani’s work at the landfill, which has been well documented, has shown that adding and recirculating liquid in the waste mass significantly increases LFG production in the landfill. By doing so, says Yazdani, a senior civil engineer for the Yolo County Department of Public Works, you increase the efficiency of LFG collection, do a better job of keeping greenhouse gases out of the atmosphere, and significantly reduce the mass of the landfill.

“We’ve demonstrated that at the small scale, because when we put the cap on and collected gas from the landfill cell we capped as a dry tomb—which is the technology today—the waste didn’t really decompose that much,” he says. “We had like 5% settlement. In the other cell, where we carefully added liquid and recirculated, we got a lot more gas. And it settled a whole lot, giving air space. The ‘dry tomb’ cell did not decompose nearly as much, so you wind up with the gas potential still in there. And it’s just sitting there dry; as soon as water gets in, gas production will go up.”

Although he’s hesitant to talk on the record about his next project because it’s in the design and approval stages, he says it would automate the monitoring and collection of LFG while preventing fugitive emissions. It’s important work and he credits the California Energy Commission and its staff for making it possible.

“Without their help and leadership,” Yazdani says, “the state of California would not have done any of these projects that we’re doing. It’s their money, their vision of seeing how renewable electricity can be tapped into. They’ve poured a ton of money into renewables, and they continue to do that because they see that there’s a huge untapped resource that’s being wasted. Especially from a source that’s not going away. If we can tap into that and offset what we produce from fossil fuel, we’re giving something back to the earth. At the same time we’re saving ourselves from breathing this polluted air. So there are a lot of benefits.”

The Tried and the True
If there’s a conventional wisdom in LFGTE, it’s that the simplest method is fueling diesel generators or, increasingly, turbines to generate electricity. As DTE’s DiGia noted, the technology is proven, with hundreds of LFGTE sites around the country that are providing power to thousands of homes and businesses. That reliability, coupled with climbing fossil fuel prices, makes electricity generation attractive—not only now, but especially in the future.

The states and the federal government are slowly coming around to the idea that LFG is a legitimate renewable energy source—green power that can relieve the economic and environmental pressures of depending on fossil fuels.

“High energy prices for all fields certainly make landfill gas a more cost-competitive alternative,” DiGia says. “It’s not free. People are always saying, ‘You’ve got that free landfill gas.’ It’s not free; there’s clearly a cost associated with the infrastructure, with the operations, the maintenance, but it can be very cost-competitive.”

Another advantage LFG has as a green power source is its capacity potential. The US—indeed, the world—is not in any danger of running out of landfills.

“When you look at electric generation,” DiGia says, “[compared with] some of the renewable sources we have in the country like solar and wind, landfill gas is very attractive, because we’ve got very high capacity factors compared to some of the other alternatives. That’s really important; it’s more than just the energy itself, it’s the capacity as well, that we can add that other renewables cannot. I think it gives us somewhat of a competitive advantage there.

“As long as we keep landfilling there’ll be landfill gas.”

Still another factor favoring electricity generation is the near-ubiquity of transmission lines. Exporting power to the grid makes economic sense to the utilities, even if they’ve been slow to embrace distributed generation.

“I think power generation will continue to be a big deal,” Augenstein says, “and one of the reasons for saying that is that when you take a look at where these landfills are located in the grid, they’re near the users. That is wonderful as far as long-range transmission is concerned, because transmission losses are a big factor for utilities. And anything generated near the user may negate the need to buy 110% of that amount of energy from a more distant provider, as an example.”

New Frontiers
Generating electricity isn’t the only application for LFG. A handful of innovative technologies—some new, some not—are on the cusp of commercialization after years of development and demonstration. For most of them, the road to the marketplace has been long and pocked by questions of economic viability. There’s no question that their processes work; the trick has been to make them commercially sustainable. Once again, however, the rising price of fossil fuels, particularly natural gas, has made them enticing alternatives to generating electricity or fueling boilers.

One of the most intriguing of these is the CO2 Wash by Acrion Technologies of Cleveland, OH. The process takes raw LFG and converts it into contaminant-free methane and virtually pure CO2. The tiny amount of contaminants are incinerated in a CO2 flare. But what makes the patented CO2 Wash unique is its ability to further convert LFG to pipeline-quality gas, CNG or LNG, methanol, or hydrogen. It can also produce CO2 that’s 99.99% pure, making it suitable for a wide variety of products.

Bill Brown, Acrion’s president, got started with the process more than 30 years ago while trying to clean up the gases that occurred from processing methane from coal. He stuck with it and eventually caught the attention of landfills that wanted to handle the CO2 in their LFG.

“The big difference, of course, between landfill gas and the natural gases and the coal gases is the pressure,” Brown says. “We need a certain pressure in order for our technology to work. So it took us a while to catch on that anybody who was doing anything with landfill gas, other than burning it, had to pressurize it or compress it in order to process it if you wanted to make pipeline gas. … We took a look at our technology in that light and it was very effective in removing the contaminants in landfill gas and we’ve moved from that point.”

Today, he says, “We’ve taken the approach to landfill gas (that) Acrion will remove the contaminants. Once you have removed the contaminants, you have a resource of methane and CO2 that can supply any market needs in a local area.”

Acrion has run a demonstration plant at the Rutgers University EcoComplex in New Jersey since 2001. While there, the company worked with Mack Trucks to produce more than 10,000 gallons of liquid methane to fuel two Waste Management refuse trucks. The trucks then ran regular collection routes for 600 hours.

Bruce Smackey, the project manager who oversaw Mack’s participation, said a preliminary evaluation of the technical and economic results was positive. LNG fuel consumption and vehicle lifting, compacting, and acceleration were quite good on Mack’s 325-horsepower, 1,100 lb/ft torque E7G gas engines.

“With a look toward the future,” Smackey went on to say, “the US is facing a highly uncertain future—the economy, energy security, and environmental impact. Taking all this into account, we find the highest beneficial use for raw landfill gas is in the production and use of transportation fuel for LNG/CNG vehicles.” Mack is reaching out to selected landfill owners and refuse haulers who share that perspective and want to secure a relatively fixed cost of operations for their future. Smackey believes a heavy reliance on imported energy—crude oil and LNG tankers—would cause added strategic risks unnecessarily in the landfill/refuse markets.

Acrion has licensed every other application of its process to FirmGreen Energy of Irvine, CA, which focuses on alternative sources. Steve Wilburn, who founded the company three years ago, says he was attracted to the CO2 Wash technology because of its versatility in processing LFG.

“You get to use the fuel one more time for a useful purpose,” Wilburn says, “as opposed to electricity, where you take it out and generate the electricity. What we would do is take that landfill gas and make a fuel out of it. And we feel that gets a larger, wider spread value for pollution abatement.”

FirmGreen, he says, is poised for tremendous growth in the coming years. The company has about $100 million in projects under development, including one in St. Louis to produce pipeline-quality gas. It will be sold under long-term contract with Laclede Gas Co.

“We look in the next two to three years to have 20 projects operational. We should have two projects operational by the middle of next year, and from there,” Wilburn says, the company has “what we call 15 good opportunities identified. These are landfills that we either have under contract, where we control the gas rights, or with joint-venture partners who control the landfill gas rights.

“We’re a very conservative company” he says, “and we’re not going to bring a product to market until it’s ready to go into the market and operate effectively, both from a technical and an economic standpoint. And we’re now at that point. You’re going to see much more activity.”

Wilburn says FirmGreen will focus on producing pipeline-quality gas. He is also interested in producing methanol to fuel miniature fuel cells, which could replace lithium-ion batteries.

It seems ambitious, but he calls it “very reasonable. All methanol in the United States, other than ours, is produced from natural gas and almost all the methanol that is imported from overseas to the United States is from natural gas as well.”

Like others in the conversion industry, he believes that “economics have caught up with potential. In the past, relatively speaking, there was low-cost natural gas available. A few years ago natural gas on the wholesale market was selling for about $2.60, $2.80 for a million Btus. Today it’s at over $6 per million. And that makes our product competitive, without subsidies.”

Acrion’s Brown agrees and says natural gas prices are pushing companies to seek alternatives to fossil fuels.

“The recent price spikes in petroleum and natural gas have really created a lot of interest in our technology,” he says. “We’re getting inquiries from all over the world. There were three on our Web site this morning, one from New Delhi, one from Beijing, and one from Madrid, Spain. Different applications—pipeline gas one of them—want to make hydrogen from landfill gas.”

Augenstein, one of the bioreactor pioneers, acknowledges that processes like CO2 Wash work, but says they’re not without their difficulties. “What you find repeatedly as you look at these processes is that they are more difficult and cost more than you initially think,” he says.

A group he’s associated with has studied employing newer technologies to treat dairy biogas for uses other than generating electricity, he says, “But you find that the costs are pretty high. The Europeans are doing these things, and they’re doing pretty well with compressed biogas and, to some extent, landfill gas and biogas-based vehicle fuels. But that is because the subsidies are much higher than would ordinarily be possible in the United States.”

Half Full, Half Empty
And yet, two of the key factors that have kept LFGTE and alternative processes like CO2 Wash in the shadows—economics and abundant, cheap fossil fuels—are changing dramatically. As Augenstein, who once worked for Exxon, notes, recent studies strongly suggest that world oil production will peak in the next five to ten years. We can’t see the bottom yet, but many smart people in the petroleum industry say the world’s cup is awfully close to half-empty.

“A couple of years ago I was reading about how there isn’t any oil problem,” he says, “that we’re getting higher recovery efficiencies from old fields and the like. And then I started looking at the peak oil issue. … There’s a lot of information, including predictions by even major oil companies, that world oil production is peaking before the year 2010. And that is a far, far, far more severe problem than anyone realizes. Because what happens is the cost of oil energy is the floor for natural gas energy, and natural gas just rides that right up. And we’re draining Canada of natural gas. Here’s where landfill gas comes in. I do think combustion is a very good thing to do, by the way; it’s gotten bashed quite a bit. But if you can’t do that you should be maximizing your recovery of landfill gas. I do think the world is in a real oil pinch—an energy pinch—and it’s bigger than we think, and landfill gas amounts to a pretty significant input. You’re talking about 1% or 2% of United States electricity, which is a huge number, actually, given the United States’ electricity use.

“I do talk to Evan Hughes at EPRI [Electric Power Research Institute] quite a lot; I used to work there. He points out that your solutions are not going to be one great big thing. They’re going to be, particularly in renewables, 2% from this, 2% from that, 2% from the other thing—from wind, from solar, from landfill gas and combustion of wood, things like that. All of that will have to add up. It goes quite a way toward solving the problem. But the economic driving factors, and the energy demand factors are going to be really, really big.

“The world can lurch around on this,” Augenstein says. “For a couple of years we may assuage the demand by getting more oil out of one resource or another, but all you’re doing when you’re using as much as oil as we are in the world, is changing the date of a big crunch by a year or so. If you found 10 billion barrels in the Arctic Wildlife Reserve, you buy four months for the world. That’s it. Whereas, if you conserve and you use landfill gas and you do all the other things you can, you’ve actually extended your energy and energy availability for many years.”

The laws of supply and demand are likely to dictate that America will turn to alternative fuels for its energy. And when it does, LFG will never have smelled so sweet.

Jim Logan is staff writer for Forester Communications.

MSW - September/October 2005