agencies, both Natural Resources Canada and Sustainable Development Technology Canada, and also lately from U.S. funding agencies like the Department of Energy. ACCN: What happens to the chemi-
cals that you remove from the gas during the cleaning process? Temperatures inside the gasifier (left) at Enerkem’s demonstration plant in Westbury, Que. are typically 700° - 800°C. Waste is fed continuously by a feedscrew (bottom right, yellow). The blue module on the top left is a cyclone for the gas cleaning process.
Enerkem Inc.
E.C.: Organics are broken apart into
small molecules that are part of our mix for the synthesis. For instance, we transform creosote into carbon monoxide, methane and hydrogen, which are desirable compounds for us. As for inorganics, we have chlorine, which comes from PVC. It will form hydrogen chloride, and you have to neutralize that by adding lime. We recover it as an innocuous salt, typically calcium chloride. Sulphur is always present, and that can form hydrogen sulphide. We use the same technique; we neutralize the sulphur and produce natural forms of sulphides. Most metals will stay as innocuous oxides, but you could have some that are volatile either by themselves or as salts. For example, suppose someone has thrown a battery or a thermometer into the garbage. Some mercury will form into gas, because mercury is very volatile. At the end of the gas conditioning system, we have a getter, which is functionalized activated carbon that gets this mercury and transforms it into mercury sulphide. That’s how it is found in nature, and it is innocuous. A small amount of innocuous solids are produced in our plants. These salts could be used for additives for cement manufacturing, aggregate materials for construction (that is, in concrete or asphalt), or additives for brick manufacturing or landfilling.
ACCN: How does the amount of energy that it takes to gasify the material
compare to the amount of energy you get out in the form of ethanol? E.C.: Let’s say we go all the way to ethanol. The energy efficiency is typically 40 per
cent. This is the energy contained in the ethanol produced, divided by the energy in the feedstock, plus any other energy that you add to the system. We can operate in two ways: we can import electricity, or we can produce our own electricity. In Quebec, electricity is rather cheap, so we have operated using electricity from Hydro-Québec. In Edmonton, we plan to buy the electricity locally as well. We are now at around 35 to 36 per cent efficiency. Eventually, we’re going to put in an engine that will be able to produce electricity and achieve a self-sufficient system. At that time the efficiency will be 40 per cent. ACCN: The idea of producing fuel from municipal waste is very attractive;
why did it take until now to gain traction? E.C.: I think everything in life has its time. In the fifties and the sixties they asked
“why don’t we get some electricity from waste?” So then incineration came, particularly in Europe and Japan. Today, there are a few visionaries, among them Enerkem, that ask “Why don’t we use carbon for a more valuable application than just electricity?” That’s the new paradigm, to capture the carbon in waste and use it as a valuable resource. Our goal is (and I’ll use the Latin word) to valorize carbon. We want to give added value to carbon in waste, and you cannot do that by only heat or electricity production. You have to go into chemical or biochemical production. Soon, people will talk about making garbage into fibres, or into structures, or into fuels. It’s coming, but society wasn’t ready for it until now. Want to share your thoughts on this article? Write to us at magazine@accn.ca
January 2011 CAnadian Chemical News 23