It's been one of the most enticing alternative fuel concepts in the waste-hauling business: converting the methane produced by rotting landfill trash into liquefied natural gas (LNG) or even a form of diesel fuel that can, in turn, power a variety of heavy-duty trucks working in many different applications.

Waste companies have worked for years to make this concept a reality, and it's not hard to understand why, for the very trash they get paid to haul away ends up becoming the fuel powering the collection trucks.

"Basically, your landfill becomes your own little Saudi Arabia," says David McKenna, product marketing manager for engines, transmissions and axles for Greensboro, N.C.-based Mack Trucks. "And when diesel fuel is costing $2.80 a gallon again, it suddenly becomes much more economical on a long-term basis to be able to make your own fuel."

Houston-based Waste Management (WM) is one waste company that's worked hard over the years to find a way to economically produce fuel from the gas produced by their landfills. The firm has worked with Mack to fine-tune LNG-powered refuse trucks along the way.

Now it seems WM may have finally made it happen. Working in partnership with Linde North America, part of The Linde Group, a Murray Hill, N.J.-based engineering company, WM recently opened a landfill gas (LFG) collection and refining plant at its Altamont Landfill near Livermore, Calif.

The plant, which Linde built and operates, purifies and liquefies landfill gas that WM collects from the site. The plant is designed to produce up to 13,000 gallons of LNG a day — enough to fuel 300 of the 485 LNG-powered collection vehicles that WM uses in California.

Since beginning operations last September, the Altamont plant — currently the world's largest LFG to LNG facility — has produced 200,000 gallons of LNG, says Duane Woods, senior vice president of WM's Western Group. "We've been working for eight years to achieve this, for the ability to use recovered landfill gas to fuel our hauling fleet offers significant environmental benefits to the communities we serve in California and is a great example of how we are committed to recovering resources in waste," he adds.

LNG produced from landfills has been designated a "super-ultra-low carbon fuel" by the California Air Resources Board (CARB), and the Altamont project is expected to reduce carbon dioxide emissions by nearly 30,000 tons a year. Four California state government agencies — the California Integrated Waste Management Board, CARB, the California Energy Commission and the South Coast Air Quality Management District — made significant contributions to get the $15.5 million Altamont project off the ground, significantly lowering the research and development costs for WM and Linde.

Just the Latest Step

While WM's Altamont plant marks the first step in using LFG to ultimately power vehicles, it's not the first — nor will it be the last — effort to create usable vehicle fuel from landfill waste. In 2006, Issaquah, Wash.-based Green Power Inc. claimed to have developed a method of inexpensively converting biomass and household waste into high-grade diesel fuel, a process the firm dubbed "NanoDiesel."

In March 2008, Green Power completed its first refinery plant prototype outside Pasco, Wash. The company says its plant is capable of processing 100 tons of municipal and other waste per day in a low-heat and low-pressure catalytic system — converting waste into a variety of fuels, including diesel, kerosene and fuel oil.

The preparation of the incoming waste stream includes chopping up the garbage and removing metals, glass and sand, which leaves about two-thirds of the waste to be processed and refined into fuel and electricity. Materials that can be converted to diesel fuel through this process include plastics (including PVCs), rubber, waste oils, agricultural wastes (food and animal waste) and wood.

Green Power said the cost of producing this diesel fuel is about 60 cents per gallon, though covering capitalization, maintenance, marketing and other costs pushes the overall expenses for such a plant much higher. The company says the conversion of input waste to fuel output is around 25 percent to 30 percent efficient, so that one ton of input waste will produce around 120 gallons of diesel, with the diesel produced purportedly a pure hydrocarbon diesel, equivalent to what comes out of the oil fields.

Trucks OEMs getting involved

Even some truck manufacturers are getting involved in trash-to-truck-fuel endeavors, not only in response to the growing need for low-emission alternative fuel vehicles but also for the ability to deliver both vehicle and fuel in one package.

For example, Mack Trucks is working with Terracastus Technologies — both owned by Sweden's AB Volvo — to develop a "total solution" landfill gas product that offers fuel production technology combined with natural gas-powered vehicles. Though the new venture is playing its cards close to its vest for now, Mack says the eventual goal is to create a "soup to nuts" package for refuse companies: the ability to buy landfill gas refining technology as well as natural gas-powered refuse trucks all through one firm. "Natural gas has a number of significant benefits," said Tom Kelly, Mack's senior vice president of product portfolio management. "It burns very cleanly, and it's comparable to diesel in terms of cost over the life of the vehicle." He also noted that Mack's refuse truck chassis has been specifically engineered and built to operate on natural gas, using ISL G engines from Columbus, Ind.-based Cummins Inc.

Mack has been investing in natural gas vehicle research for over two decades. In 2002, the OEM worked with Cleveland-based Acrion Technologies and others on a pilot project to recover LFG and convert it to LNG for trucks serving the landfill. The project took place at a landfill in Burlington County, N.J., and produced more than 10,000 gallons of LNG, which powered two Mack refuse trucks owned by WM for 600 hours of operation each during a four-month field tests.

The results of that test and WM's Altamont facility demonstrate that LFG may provide waste firms that have landfill operations with an economically sustainable and environmentally friendly way to fuel their collection trucks.

Sean Kilcarr is the senior editor of Fleet Owner, a sister publication of Waste Age.

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Want to Know More About Alternative Fuels?

This year's WasteExpo conference session includes the "Greening Your Fleet" session, which will be held on Monday, May 3, from 3:15 p.m. to 4:30 p.m. The session is part of the Green Management Track. Scheduled speakers include Anthony Ciofalo of Clean Energy and Joanna Underwood of Energy Vision.

Trash to Truck Fuel: How It Works

So how does one go about converting landfill gas (LFG) into usable truck fuel, anyways? "The process to convert landfill gas to LNG [liquefied natural gas] is actually very quick — on the order of minutes," says Bryan Luftglass, head of chemistry, energy and environmental solutions for Linde North America, which owns and operates the LFG collection and refining plant at Waste Management's Altamont Landfill in Livermore, Calif. "This isn't like, say, a fermentation process where you need a reactor that has a very long residence time. Much of the heavy lifting has already been done by the microbes in the landfill itself that have converted garbage to methane through a natural decomposition process."

The key for Linde is first recovering the methane, then separating it from all the other components present in landfill gas. Once the gas is captured and purified, the Linde plant chills the purified methane down to minus 260 degrees Fahrenheit to liquefy it, Luftglass says.

The plant is designed to produce 80,000 to 90,000 gallons each week — enough LNG to replace more than 50,000 gallons of diesel fuel. "To put it another way, we make enough fuel so that we could power 100 diesel trucks to drive across the U.S. every week," says Steve Eckhardt, head of business development for alternative energy at Linde.

And Eckhardt believes this process can certainly create a long-term, steady source of fuel. "There are at least 300 landfills big enough to economically produce LNG, which is enough to serve every one of the roughly 140,000 refuse trucks operating in the U.S.," he says.

"The real beauty is that collection or transfer trucks are going to the landfill anyway, so why not have more fueling right there using fuel produced right there?" Eckhardt adds. "I just don't think it's sunk in yet just how methane resource-rich the U.S. really is. When it does sink in, more and more fleets will be willing to take a serious look at this."