Gavin Schlissel, 2013, Mechanical and Aerospace Engineering

I spent my Energy Grand Challenge internship investigating problems with wood gas filtration with Professor Robert Dibble at UC Berkeley. Wood gas is a renewable, sustainable, carbon-neutral fuel source that can easily be obtained by heating wood (without burning it) through a process called wood gasification. The gasification process releases wood gas along with tar and ash. Pure wood gas can be used to power gas turbines to generate electricity, but the process of purifying wood gas requires consumable solvents, which makes it extremely expensive. Last summer, I tested the idea that a silicon carbide diesel particulate filter—like those that catch soot in diesel cars and buses—could be used to filter tar and ash from wood gas. I hoped that because silicon carbide can withstand temperatures up to 2000˚C, it would be possible to burn the trapped tar and ash out of a clogged filter leaving the filter clean and fully functional. If the idea proved possible, it would eliminate the need for consumable solvents in the wood gas filtration process. The filter proved very effective in filtering tar and ash from wood gas, however the filter could not stand temperatures hot enough to oxidize waste ash. I determined that because the diesel particulate filter cannot be cleaned effectively, it is not a suitable replacement for current filtration systems.