Enerkem produces second-generation biofuels and green chemicals using a thermo-chemical gasification process to produce a uniform synthetic gas ("syngas"). This syngas is subsequently converted into liquid fuels, such as ethanol, as well as biochemicals.
Enerkem's gasification and catalytic synthesis technology platform is the result of several years of research. It includes a number of processes that have been tested in the laboratory and at the pilot plant. Enerkem's technology converts one tonne of raw material (dry base) into 360 litres of cellulosic ethanol, which is enough to drive a distance of approximately 2500 kilometres (a drive from Winnipeg to Montreal or from Los Angeles to Houston).
Enerkem can use diverse feedstocks, such as sorted municipal solid waste, construction and demolition wood, treated wood, as well as forest residues and agricultural waste.
Its technology can also convert syngas into other fuels, including synthetic diesel, synthetic gasoline, and dimethyl ether, as well as green chemicals.
In a recent joint publication released by the Sierra Club and Worldwatch Institute, entitled Smart Choices for Biofuels(p.7), thermo-chemical technologies are highlighted as having “a potential advantage over biochemical technologies as they can convert almost any kind of biomass into fuel”.
There are 4 steps in Enerkem's process:
Step 1 - Feedstock pre-treatment
The feedstock is dried, sorted, and shredded, and then stored in a container that is connected to the gasifier via a front-end feeding system.
Step 2 - Gasification
The gasification process converts carbon-rich residues into a syngas. Enerkem's technology is based on a bubbling fluidized bed reactor with a front-end feeding system that is capable of handling fluffy material with no need to pelletize it. Slurries or liquids can also be fed into the gasifier through appropriately designed injectors.
The gasification is carried out using air as a partial oxidation agent or using oxygen-enriched air, with the oxygen-enrichment level tailored to the desired composition of the synthetic gas. The presence of steam at a specific partial pressure is also part of the process.
The gasifier operates at low severities (temperatures of approximately 700º C and pressures below 10 atm), which allows for the use of known, available, and inexpensive construction materials and refractories.
Step 3 - Cleaning and conditioning of the synthetic gas
The gas is cleaned and conditioned for use with existing and known catalysts. This is accomplished through a sequential conditioning system, which includes cyclonic removal of inerts, secondary carbon/tar conversion, heat recovery units, and reinjection of tar/fines into the reactor. The gas produced by this process is ready for conversion into liquid fuel.
Step 4 - Conversion into liquid fuel
Using a sequential catalytic conversion process, the syngas is finally converted into high-value, market-ready fuels and chemicals. Products, such as methanol, can be sold directly or used as intermediate products in the creation of other products, such as ethanol, synthetic diesel, dimethyl ether, and synthetic gasoline.
