PROCESSWEST Magazine Online

Technology Profile: From waste to biofuels

October 18, 2015   Don Horne




Can gasification solve the world’s garbage problem?

If someone suggested it’s possible to convert an old couch into electricity or transportation fuel or a plastic container, you might, understandably, be skeptical.

But the technology to do just that has existed for some time, and is once again making serious inroads as a source of energy and feedstock for further production.

The technology is called gasification and it’s been around in various forms since it was discovered in the early 17th century by Jan Baptista Van Helmont, a Belgian chemist and physician, who was able to produce gas from heating wood or coal. During the 1800s, gasification was used to produce fuel, known as “town gas,” for commercial and residential heating and lighting, It was the development of cheap (and safer) electric lighting along with natural gas resources that eventually replaced the widespread demand for town gas and the need for gasification in the early 1900s.

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However, for some countries without major resources of petroleum, gasification served as a significant source of fuel during the war years and afterwards. Even the U.S. invested significantly into research and development of gasification technology for both electricity and liquid fuels production after the Arab oil embargo in the early 1970s, while some European countries constructed a number of gasification plants to generate electricity. Power generation is still the primary application for gasification units, with much of it based on the use of coal as a feedstock.

But there’s an increasing movement towards employing biomass feedstocks such as agricultural, forestry or municipal waste. Gasification facilities that process biomass have the capability to produce synthesis gas (syngas), which can then produce electricity as well as serving as feedstock for clean transportation fuels, chemicals and gaseous fuel for fuel cells. Not only do these gasification technologies contribute substantially to the diversion of waste from landfills, in general, they produce considerably less emissions during the gasification process while producing cleaner feedstocks for further production.

And, according to the U.S. Department of Energy’s National Energy Technology Laboratory, “gasification processes used today are already able to clean syngas beyond U.S. Environmental Protection Agency requirements (current and proposed), as demonstrated by currently commercial chemical production plants that require ultra-clean syngas to protect the integrity of expensive catalysts.”

Developing those gasification technologies has been a long pains-taking process. Take the example of Enerkem Inc., based in Montreal, which founded in 2000 by father and son team Esteban and Vincent Chornet. Esteban — who is now professor emeritus at the University of Sherbrooke and holds a degree in industrial engineering from ETSIIB in Barcelona, Catalunya (Spain) and a Ph.D. in chemical engineering from Lehigh University in Pennsylvania — serves as chief technology officer for Enerkem. Inspired during his childhood by factory owners in his native Catalona, Spain, who used gasification to generate electricity, Chornet went on to teach and conduct advanced research in the fields of biomass, energy, and environment prior to forming Enerkem with Vincent, who specialized in developing and funding industrial projects and start-up companies in the energy and specialty chemicals sectors.

The technology used by Enerkem has roots in the research carried out by Chornet during the 1980s, says Marie-Hélène Labrie, Enerkem’s senior vice-president of government affairs and communications. “The dots connected for him in the 1980s and 1990s to use municipal waste as a feedstock for gasification technology,” says Labrie. ‘To develop the technology which Enerkem now uses, it has progressed through all the necessary phases over the past 15 years; from the lab to the pilot stage, testing more than 20 types of feedstock, then on to the demonstration and large industrial scales.

And that’s considered a normal length of development for this type of breakthrough technology.” By 2003, the Chornets had set up and were operating a pilot gasification facility in Sherbrooke, Que., followed by the construction and start-up phase for syngas and biofuels production at the Enerkem Westbury demonstration plant near Sherbrooke in 2009.

In 2008, Enerkem not only joined forces with GreenField Specialty Alcohols Inc. to incorporate Enerkem technology on the site of GreenField’s corn ethanol plant in Varennes, Que., but the company also announced its plan to build the world’s first commercial-scale municipal waste-to-biofuels facility with the City of Edmonton. The Westbury demonstration facility allowed Enerkem to scale up its technology to the commercial level for facilities such as the Edmonton plant. The Westbury plant uses discarded electrical and telephone poles, as well as railway ties as the waste feedstock. It also tests various other kinds of feedstock that may be suggested by clients and partners. The plant also serves for the development of new products and as a training centre for plant technicians and operators. Enerkem Alberta Biofuels LP’s gasification plant that was built and is operating at the Edmonton Waste-to-Biofuels and Chemicals Facility is considered the first industrialscale waste-to-biofuels facility of its kind to convert household garbage into clean syngas to be used as feedstock for ethanol and methanol.

In the Enerkem process at Edmonton, the waste feedstock is the non-recyclable and non-compostable part of the City’s residential waste stream. The waste is then first prepared by removing inert materials such as glass and metals, which are not carbon rich. Those materials are transported away for recycling. The qualified waste is shredded into small pieces, about two inches square. Carbonaceous slurries or liquids can also be fed into the gasifier through appropriately designed injectors. The waste feedstock is fed into the bubbling fluidized bed gasifier — essentially, a reactor or vessel in which the feedstock is forced to mix with steam at a controlled partial pressure, with oxygen-enriched air acting as a partial oxidation agent. The “bed” refers to the area in the reactor where an inert material (one that doesn’t react chemically), such as sand, becomes suspended or “fluidized” leading to the forced mixture of the feedstock and the oxygen blend.

Conversion of the feedstock into syngas (a combination of hydrogen and carbon monoxide) during this stage of the process takes only seconds. The syngas, sand and residue, formed from the gasification process, exit into a cyclone vessel to be separated. A cyclone separator operates using centrifugal force to spin the oxygen-particle mixture. As the cyclone rotates, the sand and inert particles are pressed against the outer wall by centrifugal force and decelerate. Because the particles are now out of the air current, they drop to the floor where the sand is recycled to the gasifier and the char is moved out to be used for various products such as aggregates and construction materials.

The syngas, meanwhile, is piped into scrubbing towers for cleaning before being stored in preparation for processing into converted into biofuels, methanol, ethanol or other renewable chemicals using catalysts. Methanol is a feedstock for the production of secondary chemicals such as olefins, acrylic acid, n-Propanol, and n-Butanol, which can then be used to form thousands of everyday products. Enerkem commissioned the Edmonton gasification facility in June 2014 and has initiated production of biomethanol from its syngas. Labrie says there will be a shutdown to construct the methanol/ethanol conversion unit. She says incorporation of the conversion unit is crucial because it means the company will be able access the ethanol market, which is being driven by the renewable energy standards in North America, such as the five per cent ethanol blend requirement (some areas have higher blend requirements).

“Certainly, there are some markets that hold higher potential than others,” says Labrie. “For instance, there is legislation in place in California requiring low-carbon fuels, which gives us an advantage because fuels produced from waste feedstock are lower carbon. Our business model is quite attractive from a cost standpoint because we use inexpensive feedstock and our technology is extremely efficient to build because it’s designed to be put together as pre-fabricated modules.”

Even more promising for companies offering waste-to-fuel technology are the overseas nations such as China that are looking to solve huge waste problems. “We travelled to China in the fall of 2014 with a trade mission to evaluate any interest,” says Labrie. “Just to make a comparison for you: there is as much volume of waste in the in the city of Shanghai, alone, as there is in all the cities and communities in Canada. So, no question, there’s lots of opportunity there and true interest by the Chinese government.” In fact, Enerkem announced two agreements at the end of October 2014: to develop a project partnership to jointly build a municipal solid waste-to-biofuels facility in Qingdao; and with Shanghai Marine Diesel Engine Research Institute to develop a project partnership to jointly build a waste-to-biofuels facility in China.

In both cases, Enerkem will license its exclusive technology to convert a variety of waste feedstocks into biofuels and chemicals. Shortly after, Enerkem also signed an agreement with AkzoNobel of Amersterdam, a leading global paints and coatings company and a major producer of specialty chemicals, to develop a project partnership to explore the development of waste-to-chemicals facilities in Europe.

The advantages of plasma
In Europe, the economic possibilities are even more feasible, according to Walter Howard, president and chief executive of Alter NRG Corp. a Calgary based company that is building what is called the world’s largest plasma (there are larger coal gasifiers) gasification plant in the Tees Valley located in the northeast of England.

Howard says, in England, the European government has basically outlawed landfills. To dispose of waste, there’s a current tipping fee or landfill tax of $172.86/tonne.

Because of this expense, for many businesses, it’s much more economical to ship waste to Europe and, especially, to China, which has become an enormous importer of waste, particularly plastics. Alter NRG offers an alternative market for the mountains of waste being produced in England. The company’s project in the Tees Valley consists of two separate gasification facilities. Its Tees Valley No. 1 project will use 950 tons per day of municipal waste feedstock to produce three million MMBtu/year of syngas — enough to produce 800 to 1,000 Bbls/ day of biofuels, although the plant will actually generate 50 MW of electricity.

The second facility is expected to produce additional 50 MW of electricity capable of providing renewable energy for 50,000 homes. The two facilities are expected to be able to produce enough electricity for 100,000 homes. While the technology used is also gasification, the Alter NRG technology uses plasma gasification to control temperature while breaking down the waste. This particular type of plasma technology has a direct connection with the NASA’s space program. It was developed by Westinghouse Electric Co., prior to its corporate breakup in 1996, to sell to NASA for simulating spacecraft re-entry conditions of more than 5,500 C (10,000 F), as well as for commercial uses.

The extreme heat produced by the plasma torch made it suitable for a variety of uses “In fact, there is currently one of our plasma torches still in use after 20 years that is used to melt faulty engine blocks back into cast iron,” says Howard. In the 1990s, when Westinghouse Electric split into component companies, the plasma torch subsection was purchased by former Westinghouse employees and named Westinghouse Plasma Corp. By that time, the technology had been adapted to process hazardous wastes such as electronic parts containing PCBs. In the mid-1990s, the company successfully applied the technology to municipal solid waste in a joint pilot program with Hitachi Metals of Japan, proving its capability not only to produce steam and power but also syngas.

This eventually led to full scale gasification facilities in Mihama-Mikata and Utashinai Japan, which both began commercial operation in 2002 and 2003 and continue operating today at Mihama-Mikata (Utashinai lost its waste supply contract a year ago). The experience gained at the two Japanese facilities was used to create the next generation gasifier, which was commissioned in 2009 in Pune, India. That facility treats hazardous wastes from more than 40 different industries.

In 2007, shortly after Alter NRG was incorporated to pursue alternative energy producing technologies, the company acquired Westinghouse Plasma as a subsidiary, along with its technology. Since then, its plasma torch technology has been applied to a wide variety of uses such as metals recycling, catalyst re-forming, heating of blast furnaces, cleaning industrial gases and, of course, its gasifier commercial facilities. You could say plasma is an unusual state of matter compared to the three other fundamental states of matter — that is, solid, liquid and gas.

Essentially, plasma is defined as thermal energy at extremely high temperatures. It’s an ionized gas generated when an electrical charge passes through a gas. Lightning produces plasma when it superheats the air around the lightning bolt at temperatures reaching 20,000 C, creating the flash we see as a bolt. Plasma torches such as Westinghouse Plasma’s replace the lightning by using electric arcs to convert the electrical energy into the intense heat required to generate the chemical reactions that will transmute the waste feedstock into syngas. The gasification process actually begins with a feedstock separation stage. As Howard explains, the Westinghouse

Plasma technology has specific advantages even at the initial step. “The Holy Grail belongs to whoever can make high quality syngas from cheap feedstock,” he says. “Most gasification processes require consistent material such as coal or clean, dry wood chips. It means the heat required in the gasification stage can also remain consistent. But, nobody pays you to take away clean, dry coal, whereas, in the waste business it’s the opposite. The waste generators must pay to have the waste removed, which changes the economics for the gasification operator.”

As far as what type of wastes are compatible with a plasma gasifier for feedstock, different commercial settings generate types of waste. In the Tees Valley setting, as in most developed countries, there is already a recycling program separating the glass and recyclable plastic from the waste stream. The remaining material is shredded and shipped to the gasification facility. Metals are also removed, although, some trace metals sneak through and will be melted down into molten slag. That’s also the case with waste rubber which is usually in the form of tires with steel belts. If those same tires were processed in a conventional incinerator, the result would be a pile of tangled wire in the incinerator, says Howard.

“Our units will completely melt that steel and it can become a revenue stream,” he says. “So, our facility gets a lot of everything. For instance, one truck may have dry paper, but if it’s shiny paper, then it has a coating of kaolin, which is an industrial clay mineral. Removing the clay from the paper is very difficult and means the paper is then non-recyclable, but is great feedstock for us. “The next truck may have kitchen waste or crushed furniture or shredded auto residue. For conventional waste processing, you can separate steel from copper. But what about the mess of foam rubber, carpeting and plastic. What do you do with it? Well, all of that becomes viable feedstock to be fed into the gasifier because of the heat the plasma torch can produce and because of the technology’s ability to control the temperature. “The torches are able to sense through computerized controls to pump additional heat into the gasifier as needed. Or, it can go down to minimal heat input for other waste such as rubber.”

The China factor
While technologies are being developed to solve the world’s enormous waste problem, the question remains as to whether the economics support it? For both Enerkem and Alter NRG, Europe and China both hold the potential for economic viability. As stated above, Enerkem has opened important markets with agreements in both China and Europe. Alter NRG, too, has made a major move into the Asian landscape with the announcement in 2015 that it has been acquired by Harvest International New Energy, Inc. wholly owned by Sunshine Kaidi New Energy Group Co., a privately held multi-billion dollar company in China. Harvest International is focused on investing in and developing renewable energy technology.

An interesting side note to this acquisition is that, in 2014, Harvest International also acquired a division of Los Angeles-based Rentech Inc. and its biomass gasifier technology. Rentech had previously announced plans to build a gasifier at White River, Ont., to produce high-quality jet fuel. In 2010, United Airlines flew the first commercial flight in the U.S. on approved synthetic fuels, with a 60/40 blend of Rentech’s RenJet and traditional Jet- A fuel. Rentech has since decommissioned its product demonstration unit and now focuses on wood fibre processing and nitrogen fertilizer businesses.

That comes as no surprise to Howard who believes there are a number of obstacles to the viability of producing fuel from waste in Canada.

“You can’t collect enough garbage in order to ship to a central processing plant to produce enough liquid. There’s not a city big enough in Canada to produce fuel on that scale. But it can work with a population such as China. And, China has a specific strategy. They are already building facilities in China to make liquid fuels. Kaidi will now be using our plasma technology as well as Rentech’s technology to produce even more fuels.”
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Ernest Granson is a Calgarybased writer and editor, and a contributor to PROCESSWest.


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