LFG in Action

Jan. 4, 2014

The current state of utilizing landfill gas in the US is primarily focused on producing heat energy, electricity, and alternative fuels, points out Gil M. Haines, P.E., BCEE, managing engineer for Brown and Caldwell.

“Landfills are tightly regulated under strict state and federal air quality regulations where owners and operators are required to capture the LFG and destroy it in a flare or combustion device,” Haines says. “As this is an effective measure for controlling fugitive emissions and improving air quality, an important natural gas resource is realized.”

Economics continue to be a driving force behind any LFGTE project, Haines points out.

Managing municipal solid waste is more than landfilling: publicity, education, engineering, long-term planning, and landfill gas waste-to-energy are specialties needed in today’s complex environment. We’ve created a handy infographic featuring 6 tips to improve landfill management and achieve excellence in operations.  6 Tips for Excellence in Landfill Operations. Download it now!

“Feasibility studies and evaluations are an important first step in determining the viability of an LFGTE project at a landfill,” he says. “The proximity of the end user to the landfill and LFG quality required for the project present some challenges that require further study.”

Another challenge is to fit the right LFG technology to a facility, says Haines.

“End users and the technology itself may require varying levels of LFG treatment to improve LFG quality and to remove unwanted constituents from the gas,” he says. “For instance, siloxanes will cause excessive engine wear for internal combustion engines, so a moisture and siloxane removal system will be needed for this LFGTE technology.

“The technological processes for LFG treatment are tailored for the specific use, thereby requiring capital investments up front for equipment and infrastructure for various stages of treatment.”

Managing municipal solid waste is more than landfilling: publicity, education, engineering, long-term planning, and landfill gas waste-to-energy are specialties needed in today’s complex environment. We’ve created a handy infographic featuring 6 tips to improve landfill management and achieve excellence in operations. 6 Tips for Excellence in Landfill Operations. Download it now!  

CNG projects require the highest level of treatment for removal of oxygen, nitrogen, carbon dioxide, and volatile organic compounds (VOC) to produce a pipeline-quality gas for use in vehicles, Haines points out.

“Therefore, this technology requires a higher level of capital investment, creating a beneficial environment for public-private partnerships and for state and federal grants and funding opportunities.”

An LFGTE project begins with an effective gas collection system comprising gas extraction wells in the waste, adjustable high-quality wellheads, gas piping systems, and liquid removal and handling components within the system, Haines says.

“This technology has been consistent for years and has shown improvements in recent years with better quality components,” he adds. “It is paramount that the system is functioning at its top efficiency to get the high LFG yield from the landfill. These systems also are used to control odors, LFG migration, and groundwater impacts.

“We have found that the higher level of treatment employed on the LFG along with proper maintenance of the components will provide longer life for the LFGTE project,” he says. “Testing of the landfill gas in advance of a project will provide useful information as to the treatment technology recommended prior to its use.”

Currently, “there is still a lot of momentum with project development, albeit slow since the retirement of the federal stimulus plan, which provided funding for various types of project develop efforts for landfill gas projects,” Brian Guzzone, director of waste and climate projects for the Eastern Research Group, notes.

Once that expired, there was a slight decrease in the number of projects, but the growth in the industry is still occurring, driven by other factors.

“If it’s not tax credits or tax incentives, it’s factors such as alternative vehicle fuel,” says Guzzone. “You’re seeing more and more waste companies converting fleets to alternative fuels and landfills are obviously a logical choice, given their presence right where the waste trucks are visiting every day. They are developing a fueling station for those vehicles.”

Some of the barriers are the same barriers that have existed in the last 40 years and have evolved over time, resulting from the complexities of such issues as electricity projects.

“There is more focus on factors such as siloxanes and how that affects engines, and that’s because of the way society is changing,” Guzzone points out. “There are more materials being deposited in landfills that create siloxanes, which end up in the landfill gas and end up in engines.”

The technologies are very commercially proven, Guzzone points out.

“They’ve been around for a long time-it’s just a matter of making them efficient,” he says. “Technologies like vehicle fuels or other types of technologies that weren’t as prevalent in our industry have come online, and they have their own barriers. You have to make sure you have the right amount and quality of gas and that the economics for these projects will be viable.

“But there are solutions, because we have more than 600 projects today as a result, so the industry is still continuing to find ways to overcome those barriers.”

Entities can get creative with financing options.

“There are third-party developers like Ameresco that would come in and offer to take all of the risk and assume to either own and operate a project, or build it and operate it for the landfill, or just build it and the landfill can operate it, or have another party operate it,” Guzzone says.

The projects must be designed to meet the needs of the clients so that it makes the most sense for the client and developer economically, he adds.

“A lot of times where you find projects fall apart is exactly because you can’t make the numbers work because one or more parties is either wanting too much out of the deal or there’s not enough skin in the game to make the project feasible economically,” he adds.

There are other types of ways projects are structured.

“There’s one called the “˜do it yourself’ project,” says Guzzone. “These are projects that you start to see from municipalities or end users of the gas that are starting to become owners of the projects or operators of those projects, so there’s more growth in that area.

While one may assume that the community will support landfill-gas-to-energy projects, that’s not always the case, Guzzone says.

“The best thing we’ve learned in the industry over many years is engaging stakeholders in the process as early as possible. The worst thing you can do in a community is to do something at the landfill that they’re not aware of and think can affect them negatively.”

If an entity does not communicate the many benefits that far outweigh the negatives in terms of reducing greenhouse gas emissions and improving local air quality, anybody can go on the Internet now and find a problem with a landfill gas project, Guzzone says

The end product after landfill gas collection is something in the order of 45% to 55% or even richer in methane, says Steve Hamilton, a vice president with SCS Engineers and manager of its energy group.

“Natural gas has almost 100% methane in it, plus some other elements, so it’s like a diluted natural gas,” Hamilton says. “You can do several things with it to make energy. You can find somebody who is close by-an industrial facility or a commercial facility-that has boilers or furnaces. You can put that gas in a dedicated pipeline and send it to a boiler or furnace where it’s used in lieu of natural gas.”

For that use, the gas is dehydrated and compressed. Hamilton points out that such an application is in place at a BMW factory near Spartanburg, SC. Another such project is in place at the University of California, Los Angeles.

Next up in terms of scale is the generation of electricity from LFG, using technologies from Caterpillar, GE Jenbacher, Cummins, and Waukesha.

“These companies produce the systems that are used to generate electricity, and that electricity can either be sold into the grid to the local utility or can be used for onsite purposes,” says Hamilton. “Sometimes there are places that have a high demand for power onsite. Perhaps they have a material recycling facility or something else and they can generate the power for themselves.

“Usually these are done through reciprocating engines, but you can also do it with combustion turbines, such as Solar Turbines in San Diego,” he says. “You can do it with microturbines from FlexEnergy and Capstone. You can do it with fuel cells.”

Electricity made from landfill gas is considered electricity from a renewable power source, which is helpful in areas with renewable portfolio standards that require utilities to produce a certain percentage of their gas from renewable sources, Hamilton points out.

“The next thing in terms of complexity is making high-Btu gas out of the landfill gas,” he says. “In this case, you’re essentially making a natural gas substitute, where the gas is dehydrated and the contaminants removed to produce a product that is nearly pure methane.

“That product is clean enough to go into a natural gas pipeline, where it can be either bought by the local utility or shipped through the pipeline to some end user somewhere who wants to use renewable gas for whatever reason,” says Hamilton.

“Landfill gas is a renewable source of energy, but it still has to compete in the market with other energy sources, and right now natural gas is relatively low in price.

“With natural gas prices that low, it makes it difficult to do the medium- or high-Btu projects to supplant natural gas unless whoever is using that natural gas is using it for its renewable qualities.”

What will drive such gas production are such incentives as tax credits or renewable identification numbers for renewable liquid vehicle fuels, says Hamilton.

IRS Section 45 tax credits are going away relatively soon-a facility has to be in place by the end of 2014 to qualify, Hamilton points out.

“Some of the programs out there that historically had supported landfill gas or other renewable energy projects are going away,” he adds. “Perhaps Congress at some point can get together and agree to continue to support renewable energy, but who knows right now?”

In the solid waste sector, Golder Associates works with the industry on developing and existing technologies used for managing solid waste, including the classic landfill design, as well as systems that come into play as the life and purpose of a landfill diminishes.

The company works with other waste issues, from remediation to medical waste, specialty waste, and the like, providing engineering services. In the area of energy, the company works with the same entities as well as developers looking to use the methane or to manage the landfill gas more efficiently, says Bruce Labno, senior consultant with Golder Associates.

“Usually, when we come in, somebody has already got a project identified,” says Labno. “We work with a community or a group of communities in establishing what they want to do, and, in that case, technologies can come to bear as part of the decision process.”

Such projects may entail a long-existing landfill with an increasing amount of gas, a landfill that is getting larger, or an existing landfill where there may be a preliminary gas collection system that needs to be expanded with the addition of new lifts.

What to do with the potential energy depends on the stage of life in which the landfill is in.

“This goes all the way to the end, where a landfill has been closed for 20-plus years and that gas supply has dwindled to nothing that can be effectively used,” says Labno. “We work with passive systems that are often used to make sure any bursts of gas are properly destroyed.”

In the case of the “sweet spot,” where there is enough gas in the line, the most effective technology has been combustion techniques associated with internal combustion engines, sometimes combustion turbines, says Labno.

At the processing point where the organic materials are separated for decomposition, use of the gas as a fuel in municipal waste combustion or processing further for a byproduct such as syngas are technologies that are “on the fringe” and not economically viable, Labno says.

The bottom line is indeed the bottom line: “The one basic underpinning to all of this is, simply, Is it economically viable to do?“ points out Labno.

There are a few variables, the first of which is the EPA regulation that landfill gas must be controlled for most landfills that are large enough-and most of them are, he says.

Those who do have gas collection systems have gas that must be managed, “otherwise it’s going to leak out to the sides, and there have historically been problems that the gas can migrate,” Labno says. “There’s a health and safety issue that’s a driving force there.”

The next step is whether or not the gas can economically be collected.

“It’s got to be collected and go to a flare anyway,” Labno says. “If you take that and put it to an engine or two or three, can you do that economically, and does that work?”

Facilities that have just enough gas for one engine tend to be fairly marginal unless there’s a substantive need for energy on the site or at a public works that could use the energy, he adds.

“There’s some offsetting done,” he says. “Almost analogous is a net metering that might occur for your home if you have a solar energy system of some kind.”

Thus, landfills that have increasing gas quantities substantive enough to support two or more engines and are slated to be there for a long time justify the economics, Labno says.

“Even if you have the LFGTE system but have no place to send the energy, and you’re a good distance from any type of energy source, or there are no electrical lines you can put your energy onto, that becomes a third issue along the way,” says Labno.

“Who’s the entity? Who owns the landfill? Is it a private concern? A public concern? Municipal? City? How does that fit the character in the case of a governmental unit, the municipality or the county?” Labno points out.

“Are they willing to operate it, maintain it, and manage it themselves? Then they don’t have to make a profit. They can just break even and use the gas effectively and say they’re being green.”

If they are willing to sell the gas, they can sell it to a third-party developer that will own and operate it and get the profits from it, but that occurs at a higher cost, Labno says.

Labno deals with renewable energy in landfill materials and landfill gas, biomass, wind, solar, and costing.

“We deal a lot with digester gas from wastewater treatment plants,” he adds. “We’ve looked into food processing and food oils. I’m dealing with a biodiesel plant now that we’ll be looking at strictly as using a variety of chemicals and brown-and-yellow grease from food processing.”

Landfill gas is a low-hanging fruit, says Labno. “It’s not going to go anywhere,” he points out. “The landfill stack is right there, and you’ve got to do something with the gas anyway.”

Companies such as Clean Energy Renewable Fuels are paving the way for CNG and LNG to become more widely used.

The company acquires raw biogas from two landfills that the company processes into pipeline-quality biomethane that becomes renewable CNG and LNG.

“We put it into the grid, and it is sold as vehicle fuel,” says Harrison Clay, president of Clean Energy subsidiary Clean Energy Renewable Fuels, a wholly owned subsidiary of the Clean Energy Fuel Corp.

“We also acquired a third-party product. Right now, the gas we’re buying from third parties is also produced at landfills, where these third parties have processed it to pipeline quality, put it into the gas grid, and sell to us, and we resell it as renewable CNG or LNG through our stations,” he adds.

The gas process technologies deployed are all conventional gas separation technologies that pull out CO2, H2S, or any other contaminants to produce an end product which is 97% or greater methane for pipeline quality, meeting the standards and quality requirements of the local public utility, Clay says.

“We’re taking an energy resource that is often flared and not being used productively, and very significant commercial quantities of methane that’s not being used, and converting it into an energy form which can be used to displace petroleum vehicle fuel,” Clay says.

“The highest-priced, dirtiest energy inputs in our economy are diesel and gasoline and our ability to displace those products with a fuel that’s derived entirely from waste is a tremendous environmental and economic opportunity for us,” he adds.

Clay doesn’t believe there’s a “˜chicken and egg’ scenario anymore with respect to CNG use in vehicles-build the stations first or retrofit the vehicles.

“At Clean Energy, we have more than 400 stations and are committed to building stations for any fleet that is willing to make the investment in acquiring vehicles, so most of our business is fleets,” he says.

The company builds a station around an anchor tenant-a refuse fleet, a trucking fleet, shuttle buses, and a transit fleet-that is already committed to converting to natural gas over their vehicle acquisition and replacement cycles.

That station typically serves other customers in the vicinity that also want to fuel with natural gas, such as Clay himself, who drives a car fueled by natural gas and fuels it at a station built for someone else.

“We built a coast-to-coast LNG and LCNG fueling station for trucks. Clean Energy has made the commitment to build the infrastructure precisely because we wanted to solve the chicken-and-egg question,” Clay says.

While financing such plants is difficult, the company has been successful in doing so to date, Clay says.

“We’ve been able to raise capital by finding long-term buyers for the fuel who are willing to pay the prices necessary to cover the cost of production,” he says. “We’re offering this renewable LNG and renewable CNG Redeem. We’re offering Redeem price parity with conventional natural gas CNG and LNG. However, that’s unlikely to last, because really the demand for the product is growing and will grow faster than the supply.”

There are challenges, including the volatility and regulatory risk around renewable fuel.

“Low-carbon fuel incentive is probably the primary risk and most significant challenge for us in terms of how we continue to grow and make this fuel available to more and more fleets,” Clay points out.

“Once you produce natural-gas-vehicle fuel or renewable CNG or renewable LNG, you’re having to compete against conventional CNG and conventional LNG, which is a very inexpensive fuel,” Clay says, adding it’s difficult to compete head to head with the price for conventional fossil fuel and natural gas in the absence of some sort of carbon pricing or incentive for renewable fuels.

“We do have programs that incentivize renewable fuel that do provide carbon pricing. We have a federal program for a renewable fuel standard, and in California we have the state’s low-carbon fuel standard,” he says.

These programs are quite new in their application to the fuel pathway, Clay says.

“The question is, Are these programs going to continue to provide meaningful incentives for producing renewable and low carbon fuels? If they do, then we certainly will continue to produce them in greater and greater volume. If there is no economic value that can be realized from the renewable or low carbon attributes of Redeem, it certainly becomes more difficult for us to grow the business.”

Barton and Loguidice is an engineering consulting firm that works with Cummins engines.

“We provide the design for a system to treat the gas and to pipeline it,” says Christopher Campman, a senior project manager. One such project is under way at the Delaware Solid Waste Authority.

“We’re treating the gas for siloxane and for the H2S issues, and then it goes through a 4-mile pipeline to a facility that has utilized it both as boiler gas and also for gensets,” says Campman.

The firm is working on another project with Cummins at the same facility going in the opposite direction to a wastewater treatment plant, where the landfill gas will be used for power in a boiler operation.

“They also have digester gas at that facility in the sewage plant, and we’re going to clean up and utilize that also,” says Campman.

While the construction of such projects is relatively simple, securing permitting can be a challenge in such endeavors, Campman says.

“Understanding the permitting process, having the state officials understand what we’re trying to do and how we’re going to accomplish it” are factors in securing permits, he says.

Granger Energy has built projects around direct use where the gas is transported directly to an industry that is burning more traditional, dirtier, and more expensive fuels such as coal and oil, says its president, Joel Zylstra.

“We’ve built projects where we can transmit gas directly to them so they can use that as their primary fuel in their boiler houses or in their turbines or whatever equipment they’re using,” he says. “There are technologies out there now where conversions can be done that can allow that type of equipment to easily burn landfill gas or landfill methane.”

The company’s staple is electrical generation.

“Electricity prices tend to be more stable compared to other fuels, like natural gas, that we might be offsetting,” he says “Natural gas was once north of $8 and recently its price was $3.50. It’s tough to have a project like that continue to be successful when economics get cut in half.

“Electricity tends to be much more stable, and the technology to convert landfill gas to electricity has been evolving for the last 25 years.”

Carlo Lebron, vice president in the waste management group for HDR Inc., points out that the current market for natural gas produced from landfill gas is challenged due to the production going on in such places as the Marcellus shale. Nevertheless, there are strong opportunities for CNG to fuel vehicles at solid waste facilities that may be retrofitting their vehicles to run off of it so they can control their own energy costs.

HDR is a full-service firm for power generation.

“In small projects, such as landfill gas to energy, we frequently will support a strategic consulting relationship or have done a lot of design of gas-to-energy systems with reciprocating engines to support that entire realm of gas utilization and energy conversion,” says Brian Bird, vice president of industrial and institutional projects in the power generation group for HDR.

“We’ve seen applications in the past where landfill gas has been of direct use, displacing natural gas in a boiler application,” he says. “We are aware of one client in particular that entered into a landfill gas purchase contract on a take-or-pay basis.

“They’re in a pretty tough situation. Obviously natural gas pricing has come down on a competitive basis, and they’re in a situation where their loads have fallen off, so economically it’s not as attractive as it was when they first went into the project.”

Bird points out to clients the costs of getting the landfill gas to a facility to convert boilers or to install generation equipment.

“When you compare that to the alternatives of continued purchase from the utility or displacing natural gas, the tighter market situation oftentimes does not support the alternative,” he adds.

Some municipal clients or private landfill operators are risk averse and are more likely to engage a developer in energy conversion projects, Bird says.

“They don’t like to stray from their core business and expertise, so they want to mitigate that risk by bringing in a developer to execute the project,” he adds. “HDR will play a role in preparing a request for proposals that an owner might entertain. It’s a pretty mature technology. Landfill-gas-to-energy has been around for a lot of projects implemented over the last 30 years.”

Factors to consider include landfill size, its current operation components, climate conditions, and how much gas is going to be available for the end use energy project, Lebron points out.

While the technologies used are fairly mature in terms of reciprocating engines that are capable of firing the lower-Btu landfill gas, “the new wrinkle that’s emerging, depending on the specific location and region of the country, is the emission regulations for reciprocating engines that have come down,” says Bird.

“That requires a site-specific evaluation of projecting emissions and what it will take to permit this kind of a project,” he adds. “It may require some additional exhaust gas cleanup and removal of particular pollutants in order to get it to a level that can be permitted. Obviously that translates into a different cost, which can adversely affect the project’s viability. Owners and developers are having to grapple with to try to make these economic situations work from a business standpoint.”

Bird adds that the engine and generation technologies coming out are more efficient.

“Yet because of the current marketplace, the overriding issue is, Are there any renewable energy credits to go along with these projects that will support them and what are the emissions permitting requirements?” he says.

“It’s really getting down to the core energy,” he adds. “Either you’re generating electricity and having to sell that into the market and determining the market price for that energy and whether it’s going to be viable or you’re displacing natural gas and with natural gas pricing so low, that can be a stretch when you put the economics together.”

In many landfill energy projects, GE’s Jenbacher gas engines come into play. They include gas-fueled reciprocating engines, packaged generator sets, and cogeneration units for power generation.

GE’s Jenbacher gas engines range in power from 0.25 to 9.5 MW, and run on either natural gas or a variety of other gases that include landfill gas. GE’s Jenbacher gas engines team focuses on technical excellence in waste heat-to-electricity generation in small-scale applications. As such, the team developed a 125-kW heat recovery generator, which recovers the waste heat from various types of engines and biomass boilers and uses it as fuel to produce electricity with no additional environmental emissions. Combustion systems, engine controls, and monitoring enable Jenbacher power generation plants to meet stringent emission standards while offering high levels of efficiency, durability, and reliability.

GE technology powers the first landfill-gas-to-energy project in Alaska. In July 2012, Doyon Utilities went online with the project, which is powered by GE’s ecomagination-qualified Jenbacher gas engines. GE’s fuel-flexible Jenbacher gas engines are powered by landfill gas created from solid waste decomposition and recovered as renewable fuel. Overall, GE’s gas engine business has more than 1,650 units operating on landfill gas with an electrical output of over 1,650 MW. Located on the Joint Base Elmendorf-Richardson in Anchorage, a joint US Army and Air Force base, the project will provide approximately half of JBER-Richardson’s 13-MW of peak demand power.

Starting in 2013, federal agencies were required to use renewable energy sources to provide at least 7.5% of total electric consumption. The GE technology allows the base to turn landfill gas into an energy source for the US military base and also into a revenue stream for the municipal utility, which currently flares the gas instead of selling it, says Dan Gavora, chief executive officer of Doyon Utilities.

“In addition, the plant will help the military improve its energy security and move closer to its renewable energy target,” he says.

Doyon will own and operate the facility and will buy the gas produced for at least the next 20 years, with an option for an extension to 40 years, under the agreement with the municipality. Additionally, the power produced will offset what the military would have to buy from the municipality, adding to more than $30 million in savings over the life of the project. The Anchorage Regional Landfill, which opened in 1987, has the capacity to hold 40 million cubic yards of waste. It is one-third full and expected to reach capacity around 2045.

As the landfill grows, so will the opportunity to increase the LFGTE plant’s capacity. For those landfill operations that look to create energy from landfill gas, having the right tools makes a difference in the success of that project. To that end, Landtec offers its expertise and technology solutions.

“We provide the instrumentation for reading the individual wells,” says Jamie Tooley, chief operations officer. “We provide portable instruments by the name of GEM, which has been an industry standard in the US. The instruments measure gas quality and flow and temperature of the gas, which is all used in the prediction of the gas production in the future and what the gas production is at the moment.” The company also supplies specialized wellheads that work in conjunction with the instrument to measure the flow and a fine-tune valve, enabling an operator to accurately turn the flow to a very small or large volume to maximize the production from the well. Landtec supplies enterprise software used by major corporations for environmental compliance.

“It takes the readings and puts it into an enterprise system for reporting to different state and federal agencies to show your environmental compliance while still maintaining the highest production or Btu value of the gas,” says Tooley.

Landtec also supplies moving stations or knockout stations that are used in the gas systems for removal of moisture within the conveyance line.

“We also supply several flow meters that are used before a plant for measuring the flow,” says Tooley. “They’re highly accurate, and they only need calibration once every five years. That was a new technology or approach to existing devices.”

The company also supplies stationary laser equipment, which is new to the industry, Tooley says.

“It never needs calibration. It measures very accurately the CH4, the CO2, and we’re releasing a CO2 laser that will be of great use to the gas-energy engines, because they really have to monitor that,” he says. “The existing technology is a chemical cell which is prone to wearing out after 12 to 18 months, and they need a lot of maintenance.

“Our laser will be able to be set in place in front of a high-Btu plant or in front of an engine assembly and not need any calibration or maintenance.”

Landtec also conducts engineering seminars for consultants in the United States and people who just got hired out of school for their introduction to landfill gas and how to apply what they’ve learned in school.

Tooley says these are exciting times for landfill-gas energy production.

“California is going to allow for landfill gas to be injected into the pipeline in 2014, where in the past we hadn’t been able to do that, so that’s going to be a very exciting opportunity,” he says. “It appears there’s a big move toward the waste operators to convert trucks or buy the collection trucks powered on natural gas so they have controlled costs on their fuel consumption.”

Tooley says he looks to see California’s innovations spread throughout the United States.

“It looks like it’s going to be an exciting future for renewable energy,” he says.

When landfills are not an option for producing energy, there are other options.

“Per ton of waste, energy-from-waste facilities generate 550 kWh of electricity versus 65 kWh derived from landfill gas projects,” says James Regan, spokesperson for Covanta Energy Corp.

Covanta owns and operates 45 waste-to-energy (WTE) facilities, primarily in North America, and 20 additional energy generation facilities in North America.

WTE is produced as such: Municipal wastes delivered to Covanta facilities are stored in a bunker and transferred to a combustion chamber where self-sustaining combustion is maintained at extremely high temperatures.

Covanta maintains the building around the tipping and bunker area under negative pressure, using the air in the combustion process to control odor.

The heat from the combustion process boils water. The steam from the boiling water is used directly, or more frequently is used to drive a turbine that generates electricity, which is distributed to the local grid.

Ash from combustion is processed to extract metal for recycling and combined with residue from the air pollution control process. The combined ash is either disposed of in a monofill—where only ash is stored—that receives only that waste, used as cover material at a conventional landfill, or landfilled with other waste.

All gases are collected, filtered, and cleaned before being emitted into the atmosphere, using state-of-the-art air pollution control technology that operates to state and federal standards.

Covanta WTE facilities recycle more than 400,000 tonnes of ferrous and over 15,000 tonnes of nonferrous metal annually.

Cornerstone Environmental Group’s BioCNG unit was formed to process LFG and other digester biogas into CNG as vehicle fuel. The system removes hydrogen sulfide, moisture, siloxanes, and volatile organic compounds by a carbon media and chilling system down to appropriate levels. The CO2 is removed via a membrane system. The end result is a product in the 97% and 98% methane range, ready for either vehicle fuel or any other energy application, meeting SAE J1616 standards.

“We currently have five new projects operational in the country that use BioCNG technology to process that gas,” says Chris Voell, who is Cornerstone’s eastern sales manager and works for the company’s BioCNG unit.

Three are at landfills: one outside of Lafayette, LA; one outside of Madison, WI, and one in Riverview, MI.

“We’re busy educating people about the possibility for this opportunity, working on installing the system at a couple of other locations, and working with clients to the process of this technology being installed at these facilities, but also learning about what natural gas vehicles are, compared to what they’re used to, what incentives are available for doing these kinds of projects, and working through the financial aspects of them,” says Voell.

Most people are educated as to the traditional use of landfill gas for electricity production or Btu applications and a smaller number of high-Btu pipeline injection projects, says Voell, adding that has comprised 99% of landfill gas applications over the last several decades.

“Not only are people most familiar with those applications, but a lot of the incentives around landfill gas energy development rotates around electricity production,” he adds. “There is a learning curve that is occurring now for people to become comfortable with this technology.”

“It’s usually been at a scale that most landfills cannot afford or don’t have the amount of gas for,” he says. “Our offering is down in the 50- to 200-cfm range to convert landfill gas into a product fuel that is 97% to 98% methane and is ready to be converted into CNG to fuel natural gas vehicles.

“There’s also a very strong and growing interest in moving away from petroleum-based vehicles, gasoline and diesel, to alternatives,” he adds. “We have the opportunity to not only have a cleaner, quieter vehicle, but we have the opportunity to do that at 25% to 50% less cost than you would pay for those petroleum products.”

For those who make an investment in biogas or a landfill-gas-to-CNG project, there is long-term fuel price control, Voell says.

“It doesn’t matter what happens with the natural gas prices,” he adds. “As long as you have a flow of landfill gas at your site, you’re able to set that cost for the next 15 or 20 years.”

The long-term value of using or selling CNG as a vehicle fuel is much higher than selling electricity, Voell contends.

“There is a better economic return,” he says. “From an economic standpoint, there is an 80% to 90% greenhouse gas reduction when you replace a garbage truck that typically runs on diesel fuel with one that runs on landfill-gas-based CNG.”

Any landfill with gas is a candidate for a project, Voell says.

“A landfill that has 100 cfm of landfill gas at 52% would yield about 400 diesel gallon equivalents [DGEs] a day from that volume of gas,” he says. “The best candidates are also those that have a fleet, either within that same organization that is ready to make the move to natural-gas vehicles or a relationship to one to convert their vehicles.”

Case in point: a city-owned landfill that contracts out for the hauling for its waste.

“If the city were to invest in a project like this and then sell the fuel to that contract hauler, that’s a great scenario,” Voell says.

One of Cornerstone’s most successful projects is the St. Landry Parish landfill in Louisiana, which is converting 50 cfm of its landfill gas to about 200 gasoline gallons equivalents a day.

“They worked with their sheriff’s fleet to convert their vehicles to dual fuel so they can run on biogas CNG or gasoline, and they also have converted some of their solid waste management vehicles,” says Voell. “That’s an example of a municipal investment at a very small scale. They are actively looking to probably quadruple the size of their project and are trying to work the vehicle fuel offtake for that.” 
About the Author

Carol Brzozowski

Carol Brzozowski specializes in topics related to resource management and technology.

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Microplastics that were fragmented from larger plastics are called secondary microplastics; they are known as primary microplastics if they originate from small size produced industrial beads, care products or textile fibers.