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 October 28, 2019
The race is on to repurpose garbage

 Towns in central and northern Maine were seeking a workable alternative to landfills and incinerators when they engaged Fiberight to build a municipal solid-waste-processing unit in the town of Hampden. In 2017, the UK-based firm began constructing a sorting facility intended to pick out and recycle metal, paper, and plastic from 135,000 metric tons (t) per year of waste generated by the towns.

The $80 million facility was to be up and running by early 2018. An engineering marvel, it would convert food waste into biogas for injection into the local gas grid, mixed paper into recyclable pulp for egg cartons, and plastic film into fuel briquettes for energy generation. In the process, the plant would reduce greenhouse gases such as carbon dioxide compared with landfills and incineration, Fiberight said.

But by March of this year, the facility was still incomplete. Local press reports noted weather-related construction delays, a challenge to the plant's environmental permits, and difficult markets for recycled materials.

Those delays point to the hurdles that municipalities face when dealing with new ways to handle and process waste. Reducing mountains of trash by turning it into fuels and chemicals would solve a lot of problems, but so far that has been difficult to do.

Several firms have tried and failed to develop new trash gasification technologies, including Range Fuels, KiOR, and Air Products and Chemicals. Air Products alone took a $1 billion write-off in 2016 for its attempt to gasify garbage and generate energy. High costs, technical complications, and cheap competing petroleum-derived fuels and chemicals doomed the projects to failure.

Yet relying on landfills is becoming increasingly costly and environmentally questionable. Tipping fees---the price charged to drop off waste at a landfill---can reach $70 per metric ton in Maine and exceed $100 in other areas of the US.

According to the US Environmental Protection Agency, each person in the US generates nearly 2.3 kg of waste per day. Of the 260 million t of municipal solid waste generated annually in the US, only about 35% is recycled or composted.

A Fiberight spokesperson indicates that the Hampden facility is now close to full operation. According to the firm's website, the company recently commissioned a food-waste digester that is making biogas to provide heat and power for some of the site's operations. Fiberight says its goal is to get the recycling rate for the communities it serves to 65%.

Achieving that goal means treating waste as a resource, Fiberight says. It's a goal shared by several companies developing waste gasification techniques. They claim that gasification can significantly reduce landfill volumes and recover energy from trash to make electricity, fuels, and chemicals. They say gasification is simpler than Fiberight's multistream approach. It also has a lower carbon footprint than simply burning trash in incinerators, which has both environmental and public perception problems.

Another virtue is that waste gasification, often coupled with a catalytic chemical transformation step, satisfies a growing call to reuse valuable materials in a circular economy in which waste is kept to a minimum.

Among the most advanced gasification technologies is one from Enerkem. The firm's process converts garbage and industrial waste into synthesis gas that is then catalyzed to methanol and ethanol for use as fuel or a chemical feedstock.

Similarly, Red Rock Biofuels is linking gasification with Fischer-Tropsch catalysis to make jet fuel, diesel, and naphtha using wood leftovers from sawmill and logging operations. Another firm, Aries Clean Energy, is developing gasification projects that convert sludge from water treatment plants and agricultural waste into electricity and a soil amendment known as biochar.

Success isn't assured. Gasification methods have been around for nearly 2 centuries to make, for instance, hydrogen from natural gas and methanol from coal. Applying such methods to inconsistent waste materials such as garbage and wood won't be as simple.

The current crop of high-tech waste converters say they will succeed where predecessors have failed. But Glen Farris, executive vice president of operations at the bioenergy consulting firm Lee Enterprises Consulting, warns that gasification will be challenged to prove its worth. Gasification also has a way to go to prove itself profitable. Even if projects achieve technical success, they will still fail if they don't provide an adequate return to investors, "no matter how green they are," says Wayne Lee, CEO of Lee Enterprises Consulting.

Enerkem is keeping things simple by not getting involved in the costly process of sorting through municipal waste. That's the job of the City of Edmonton in Alberta, where Enerkem has been operating a waste-to-ethanol plant since 2017.

According to Michel Chornet, executive vice president of project execution and plant operations at Enerkem and the person who got the plant up and running, the city keeps recyclable plastics and compostable matter and removes rocks and glass. Enerkem gets carbon-containing materials, including soiled cardboard, paper, wood, textiles, and residual nonrecyclable plastics.

After being shredded and dried, the trash enters Enerkem's gasifier, where heat in a low-oxygen environment decomposes it into a synthesis gas mostly containing hydrogen and carbon monoxide. After scrubbers remove residual CO2, chlorides, and sulfides, the syngas is catalytically converted to methanol and then ethanol.

The plant does emit CO2 and other pollutants, Chornet acknowledges, but at one-tenth the rate of a comparable-sized waste incinerator. "Our process is predicated on CO2 reduction," he says. The Edmonton facility converts 100,000 t of municipal waste annually to 36 million L of ethanol.

One supporter of Enerkem's approach is Marco J. Castaldi, a chemical engineering professor and director of the Earth Engineering Center at the City College of New York (CCNY). Not only has Enerkem used catalysts suitable for its waste-to-energy technology, but the firm has also successfully removed nearly all the CO2 from syngas so it can more easily make methanol and ethanol, he says.

Enerkem's process didn't emerge overnight. The firm started in 2000 as a spin-off from the Université de Sherbrooke, where Chornet's father, Esteban, was a professor of chemical engineering. Esteban and Chornet's brother, Vincent, cofounded the firm. Chornet, also a chemical engineer, joined in 2006 to help demonstrate the technology at a commercial scale.

Chornet attributes the Edmonton plant's success in part to 110 patents and "a lot of trade secrets and know-how" developed over the past 20 years. Enerkem now has 216 employees and has attracted funding from investors such as the Canadian energy firm Suncor Energy, Waste Management of Canada, and the venture capital firm Braemar Energy Ventures. In a recent fundraising round, in April, the firm brought in $58 million. Earlier this month, Suncor invested another $38 million.

Enerkem's success in scaling up its process has brought several new projects to its doorstep. They include a waste-to-methanol project planned for Rotterdam, the Netherlands, with partners Air Liquide, Nouryon, the Port of Rotterdam, and Shell and a project to convert waste to ethanol in Minneapolis.

Chornet won't say whether his firm's approach is profitable. But he points out that customers are willing to pay more for methanol and ethanol when they're made from recycled garbage. "Government subsidies favor us," he says. So too do mandates such as the Renewable Fuel Standard program in the US, the Low Carbon Fuel Standard Program in California, and similar requirements in Oregon and Washington.

"It's too early to tell if the first generation of commercial-scale gasification plants will be successful," says Steve Simmons, president of the solid waste management consulting firm Gershman, Brickner & Bratton. Prices for the fuels and chemicals coming out of these plants will have to go through a few economic cycles before experts come to a verdict. Even then, he says, gasification firms may need additional policy help, such as a federal carbon tax, to make the economics work.

These are interesting times for the municipal solid waste industry, Simmons points out. The sector is dealing with an increasing amount of difficult-to-recycle plastics because China stopped accepting such waste 2 years ago. As once-exported low-value trash builds up, waste handlers are finding it difficult to acquire permits for landfills in densely populated parts of the US, he says. In those places, landfill fees are rising, and municipalities are looking to alternatives such as gasification.

Tipping fees exceeding $100 per metric ton in the New York City area are what attracted Aries Clean Energy to build a fluidized-bed sewage sludge gasifier in Linden, New Jersey. "We will offer somewhat lower tipping fees" and still turn a profit, says Jeff Snyder, senior vice president of business development at the firm.

The facility now under construction will treat about 130,000 t of sludge annually from a nearby sewage-processing plant when it starts up in 2020. Aries will gasify the sludge into syngas that will fuel electrical generators for plant operations. Biochar left over will go to concrete makers as a substitute for fly ash.

Aries operates a slightly different gasification system in Lebanon, Tennessee, that processes a combination of woody biomass and sludge from a nearby sewage plant.

Snyder says Aries plans to use the Tennessee plant's technology to build small gasifiers in California that will consume agricultural waste and that could be used in the future to process forest undergrowth the state wants to remove to reduce wildfires. Aries intends to sell by-product biochar from the California gasification projects as a soil amendment, potentially sequestering CO2 "for thousands of years" and slowing climate change, a company press release says.

California is attractive to firms like Aries because the state requires utilities to pay premium prices for electricity generated from biomass, says Frederick Tornatore, chief technical officer at TSS Consultants. Biobased fuel makers can also benefit from the state's low-carbon fuel program, which offers credits worth about $150 per metric ton of CO2to low-carbon fuel makers, he says.

Utilities and refineries can buy the credits to offset their greenhouse gas emissions as part of the state's cap-and-trade program, Tornatore says. Gasification firms can get tipping fees for the solid waste they bring in from municipalities and take advantage of the state's fuel-credit system. California is a complex market, he points out, where "economics are driven by policy initiatives."

Red Rock Biofuels (RRB) is one of the firms hoping to benefit from California's low-carbon fuel standard, CEO Terry Kulesa says. The company is building a $240 million gasification plant in Lakeview, Oregon, that will convert 125,000 t per year of waste wood into 55 million L of jet fuel, diesel, and naphtha. Some of the fuel is destined for California.

The firm already has jet fuel contracts with Southwest Airlines and FedEx. Kulesa is also talking with chemical firms interested in buying the bioderived naphtha that the Lakeview facility will make. "We weren't initially expecting that," he says.

RRB, which has received $70 million in US government awards, is not a technology inventor as much as it is a technology integrator, Kulesa says. "We build, design, and run facilities," he says. The firm's designers cut their teeth learning to build cost-effective ethanol plants, he notes.

RRB is integrating gasifiers from TCG Global with Fischer-Tropsch units from Velocys to catalytically convert syngas into liquid hydrocarbons. RRB will upgrade the hydrocarbons to jet fuel, diesel, and naphtha using hydroprocessing technology from Haldor Topsoe.

Using proven technology providers will allow his firm to ultimately make a profit, Kulesa says. RRB has two more wood-to-fuel plants on the drawing board, and he expects raising funds will get easier once the Lakeview facility is up and running.

But without government policies and support that firms like RRB are getting, wood and garbage gasification processes probably wouldn't be developed, says Masoud Zabeti, a biofuels expert at Navigant Consulting.

Because of its makeup and oxygen content, biomass is a more complex feedstock than natural gas or even coal, Zabeti says. When gasified, it is likely to form tar, which interferes with syngas formation. Also, removing impurities such as sulfur and nitrogen oxides is complex and costly, he points out.

After adding technology development and distribution costs, Zabeti figures that users of fuel made from gasified biomass are paying a premium of anywhere from $300 to $1,000 per metric ton over traditional fossil fuels. Even with technology improvements, governments may need to impose a price on carbon to make waste-based fuels competitive with their petroleum-based counterparts, he says.

Ultimately, the goal is to divert as much biomass from landfills as possible while reducing greenhouse gas emissions. Doing nothing and continuing to rely on landfills is worse, CCNY's Castaldi says.

Castaldi remains bullish. Gasification developers are improving syngas purification and cleanup techniques, he says. Also, municipalities are getting better at collecting and separating waste into streams that can be easily gasified to extract their energy and carbon content.

"I'm forever optimistic that gasification advances will be made," Castaldi says.