Gasification? If you’re like 100% of people out there, you’re probably wondering what, exactly, is gasification? No, it’s not what happens to the room you’re standing in after you’ve eaten a bunch of burritos (that’s fumigation, a much different process.) In fact, gasification is a thermochemical conversion process. During the process, a carbonaceous material (such as biomass, or a fossil fuel) is reacted at a high temperature with a limited amount of oxygen and steam, to produce a substance called synthesis gas.
Synthesis gas (syngas) consists primarily of carbon monoxide, hydrogen, and carbon dioxide. Depending on the material gasified, there will likely also other trace impurities that need to be removed to produce a high quality syngas stream. What can you do with syngas? It’s actually a fuel that can be burned to produce energy, producing carbon dioxide and water (syngas burns just like any other carbon-based fuel.) Additionally, syngas can be used to produce liquid fuels and petrochemicals through a process called Fischer-Tropsch synthesis. In this process, syngas is reacted at high temperature and pressure to produce hydrocarbon chemicals chemically identical to the ones derived from oil.
You might think that this sounds advanced, and so gasification must be a new technology. Actually, it’s been around for a couple centuries. Originally, gasified wood was used in lanterns to provide lighting. Also, it was piped through towns to provide energy for heating and cooking, not unlike natural gas today. Surprisingly, syngas back then was referred to as “town gas.” More recently, syngas has been used as a transportation fuel. It was very common in WW2 Europe, where petroleum shortages forced citizens to find other energy sources. They fueled their cars with”woodgas” by attaching small wood gasifiers to their cars, and running them on syngas. Woodgas powered cars and tractors are still used today in times of energy crises, or isolated places where the cost of imported energy is very high.
Gasification is likely to play a big role in our power plants in the future. “Clean Coal” power plants use a system called Integrated Gasification Combined Cycle (IGCC.) In IGCC, the pulverized coal is first gasified to produce syngas. Water is added to the syngas so that instead of CO, H2, and CO2, the gas stream is hydrogen gas and CO2. The CO2 is then separated and stored underground, avoiding the release of large amounts of CO2 associated with coal energy.