Waste Not

FROM THE JULY ISSUE: Greenfield Global’s ethanol plant in Quebec supplements natural gas with biogas power produced through anaerobic digestion of organic waste from 27 nearby cities.
By Susanne Retka Schill | June 19, 2019

Greenfield Global is taking diversification and the biorefinery concept up a notch. For more than a year, the Canadian ethanol producer has been displacing about 15 percent of its natural gas demand at its 200 MMly (50 MMgy) ethanol plant in Varennes, Quebec, with biogas purchased from the SEMECS anaerobic digestion (AD) plant just across the street. Plans are being finalized to more than double the capacity of the SEMECS plant by 2022 and add process equipment to upgrade the biogas into renewable natural gas, as well as direct conversion of biogas to hydrogen.

Hydrogen is a fuel for the future, says Jean Roberge, vice president of renewable energy strategies for Greenfield. “When looking at the trends worldwide, hydrogen is seen as a source of energy for transportation,” he says, adding that the provincial government in Quebec is promoting future adoption of electric cars and hydrogen fuel cells for buses and heavy transport.

The Varennes AD plant is a result of another provincial policy. In 2009, the province announced its intention to ban the landfilling of organic waste by 2022, along with a program to subsidize qualifying AD and composting operations. Three regional county municipalities—MRC Marguerite d’Youville, MRC Vallée du Richelieu and MRC Rouville—joined forces to develop a project and sought an industrial partner.

What emerged was a unique plan involving the municipalities and Biogaz EG, a joint venture between Greenfield and Groupe Valorr Inc., a waste treatment firm. The project qualified for a CA$30 million ($22.4 million) provincial subsidy toward its CA$45 million ($33.6 million) capital cost.

The private/public structure has come with advantages. “Greenfield, through Biogaz EG, is a shareholder of SEMECS,” Roberge says. “Biogaz EG brings the technical expertise to the SEMECS plant, and was awarded the contract for overall management and design and construction, as well as a 20-year operating contract for the plant.”

Another advantage is a guaranteed feedstock—the three regional municipalities have jurisdiction over the handling and disposal of all the waste in the 27 cities they host, with a combined population of about 270,000. Not only are businesses and industries required to separate their organic waste, but households also separate their organic waste for curb-side, brown bin pickup.

Project Design
The Varennes AD plant is equipped with pulper and digestion technology from German company BTA International GmbH to treat source-sorted organics containing up to 10 percent contaminants. Trucks dump their loads in a building under negative pressure. A front-end loader dumps the material into a hopper, where it is conveyed into the pulper, a 32-cubic-meter vessel that utilizes water and hydraulic sheer forces to treat the waste. “The plastics and styrofoam float and a rake picks that up,” Roberge says. “The heavy fraction—stones, bones, cans—get sucked off the bottom. What remains in the middle is the mash that you use.”  

Some of the feedstock supplied by 25 industrial clients is clean, but the pulper system is robust enough to handle less-than-ideal loads. “We have a yogurt company nearby and sometimes they bring a big batch and, other times, it could be all the little cups filled with out-of-date yogurt.  We don’t have anyone at the plant that will go cup after cup and open them up—the truck dumps the load on the floor and the pulper does its job. The yogurt comes out into the digester and the plastic floats on top and we’re done.”

Designed to handle 40,000 metric tons of organic waste annually, the system produces about 18,000 tons of digestate—unconverted solids—that is applied to about 200 surrounding farms, many of which supply corn to the ethanol plant. “We do not sell the digestate to farmers, we give it to them,” Roberge says. While niche markets in Europe have valued the digestate as high as $500 per ton, no value was assigned in the SEMECS business plan, he says. “We could sign a long-term contract on the biogas, but you cannot have a long-term contract on the digestate. I’m sure, in time, we can improve the product and give it a better value.”

The digester produces 6.4 million cubic meters of raw biogas annually. If further cleaned, it would amount to 4 million cubic meters of pure methane. The ethanol plant, however, uses the raw biogas with just the water and trace sulfur removed, burning the remaining methane and carbon dioxide mixture in the ICM-designed plant’s thermal oxidizer.

With more than a year in operation, the system has worked so well that six more cities want to join, resulting in plans to increase SEMECS capacity to 100,000 metric tons per year. Expansion plans include biogas cleanup and compression to renewable natural gas for injection into the natural gas pipeline, plus the addition of a hydrogen production system.

Part of the expansion plans will be undertaken by SEMECS and part is being developed by Greenfield. Together, the green energy projects will enhance Varennes’ status as a true biorefinery. The renewable natural gas, hydrogen, biogas and digestate fertilizer amplify the core products of ethanol, distillers grains, corn oil and carbon dioxide captured and converted to dry ice by Praxair.

“The benefit for Greenfield is it increases our business base and diversifies our portfolio,” Roberge says. “We’re gaining expertise in different fields and enabling it to play in emerging energy markets. Hydrogen is soon to play an important role in the future energy basket in the world. In Europe, all you hear about is hydrogen.”

Greenfield Diversifies
The new projects at Varennes are the latest of several waste-reducing innovations at Greenfield. Its Chatham, Ontario, plant has been piping carbon dioxide and waste heat to a nearby tomato greenhouse. The company has ongoing research and development on alcohol production from industrial waste, cheese waste being one example, Roberge says. Varennes has a cellulosic ethanol research program and continues to work on hydrogen and AD technologies.

Diversification has long been a business strategy for Greenfield. The company was founded in 1989 as Sunroot, opening an industrial alcohol plant in Tiverton, Ontario. It acquired the packaging assets of Commercial Alcohols shortly after and adopted that name. In 1997, its Chatham plant opened and the company acquired Pharmco Products, a brand that is still used for its specialty chemicals.

The company rebranded as Greenfield Ethanol and expanded into fuel ethanol, opening the plant in Varennes in 2007 and another in Johnstown, Ontario, in 2008. In 2013, it adopted the name Greenfield Specialty Alcohols and in 2017, Greenfield Global. The company produces 111 MMgy of fuel ethanol and 37 MMgy of industrial-, food- beverage-grade alcohol, of which 16 MMgy is pharmaceutical-grade alcohol and specialty chemicals.

Greenfield has continually invested in innovation, says Howard Field, president and CEO. “Today, we are the largest ethanol producer in Canada and a leading producer of many grades of specialty alcohols. But we also produce and sell hundreds of products to thousands of life science, food, flavor, fragrance and beverage customers in more than 50 countries worldwide.”

Greenfield’s renewable energy division is focused on making a meaningful contribution to developing the low-carbon economy. “Our vision of a biobased economy is essential to how we think and operate at Greenfield,” Field says. “Like ethanol, we believe hydrogen and fuel cell technologies are essential in combatting climate change. So much of what we are working on aligns with hydrogen in the low-carbon economy; it’s a tremendous, innovative business platform for us. At the same time, we are helping solve real environmental challenges being faced by communities, governments and industry alike.”

Author: Susanne Retka Schill
Freelance journalist