One need not be a physicist or chemical engineer to understand what plasma gasification can mean to the future of solid waste. This intriguing technology for converting solid waste into chemicals and energy has been in the demo phase since the mid-80s. But in May it took a major step forward towards commercial deployment when Waste Management (WM) and InEnTec announced a joint venture to form S4 Energy Solutions. S4 plans to build plasma gasification plants and WM has the nationwide infrastructure to deliver a smooth flow of segregated feedstock.

WM, North America’s largest waste management company, is embracing plasma gasification for the first generation of commercial facilities. “We are choosing some sites right now and have a few identified. Short term, we are looking at three to five different locations. Long term we are going to be looking at the majority of the 50 states. We expect to announce our first plant in three to six months. At that time we will expect to have already started construction. We are beginning the permitting process in a few cases and doing prep work for those facilities,” stated Jeff Surma, president and CEO of S4.

“The point lost on a lot of people is that this technology has been around for a while. From a chemistry perspective it works,” said Joe Vaillancourt, senior vice president of S4 Energy Solutions. “What no one had done in the past is put together a model where the collection of waste can be done efficiently, routed and pre-processed efficiently. This collaboration allows the technology to marry a very large WM infrastructure that from an economic standpoint allows it to work commercially.” ...read more

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PV turns old dumps into solar assets
by Mike Breslin

Click to Enlarge - During the restoration of the author’s 1981 Chevy pickup, many rebuilt parts were utilized. Rebuilt and remanufactured parts are key to keeping maintenance costs down for older cars.

Aside from harvesting landfill gas, closed landfill acreage is largely wasteland. And where are these vast tracks of vacant land located? They are usually close to the metropolitan centers that filled them up or close to cities where large utilities are scrambling to meet renewable energy portfolio targets. This relative geography opens up large potential for the installation of plastic geomembrane caps covered with thin-film photovoltaics (PV). Very importantly, and unlike many solar or wind farms, this largely unproductive wasteland is usually sited next to power lines standing ready to deliver electricity into urban areas, which avoids building costly transmission infrastructure.

Traditional ground-mounted PV does not work for landfills because of prohibitions against drilling into soil caps to build the foundations necessary for steel racks to support conventional PV arrays, and the land is far too unstable to support other heavy structures like wind towers. After long term settlement these lands may serve as green space, golf courses or parklands, but usage is often problematic because of the underlying decomposition.

Exposed geomembrane caps are well established for closing landfills. A main advantage is that durable plastic covering is an environmentally safe and economical alternative that circumvents the high expense of buying, carting and spreading the required clay-content capping soils. Geomembranes are highly efficient in preventing rainwater from percolating through the waste and becoming troublesome leachate. And better than soil caps, they contain landfill gas for recovery while masking unpleasant odor.

Take the inherent benefits of modern geomembrane durability and combine it with the latest developments in thin-film solar technology, and many people are convinced that this is a hybrid solution with great potential. Combine a solar-geomembrane with gas recovery, and suddenly, what were once wastelands can become productive energy farms.

At least, that’s the theory. And the theory is being deployed in a few large-scale commercial applications with early indications of success. United Solar Ovonic (known as Uni-Solar), a wholly owned subsidiary of Energy Conversion Devices, has been the pioneer in developing its amorphous silicon thin-film technology for landfill geomembranes. Energy Conversion Devices has been manufacturing thin-film panels for over 20 years and has approximately 250 megawatts in operation worldwide, primarily mounted on roofs.

No other solar manufacturer is doing geomembranes at this time, although others are interested because of the potential size of the global market.

Different than the heavy crystalline-silicon solar panels with aluminum frames and glass surfaces that must be bolted down, these thin-film panels are less than a quarter-inch thick and adhesive-applied to geomembranes. Built on a flexible, stainless steel substrate, the layers of photovoltaics are encapsulated in polymers.

While having lower energy output per square foot than conventional panels, thin films cost less to manufacture and are much lighter weight. Despite requiring a larger footprint than conventional panels for equivalent electric production, Uni-Solar claims that the payback time on investment is better than conventional panels. ...read more

Commercialized plasma gasification of solid waste offered by S4 Energy

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