The key difference between biofuels that are truly green and those that aren’t is the source material: is it genuinely waste, or is it something like food or virgin wood, that could be put to better use? Well, there’s one source about which there can be no doubt: sewage sludge. And a new study says that this poo-power can produce biodiesel that costs just 10 cents more than conventional diesel.
Every year, Americans generate seven million tons of sewage sludge — the semi-solid stuff that remains after wastewater is treated — and disposing of it is a real mess. Adding oil-producing microorganisms and processing the results into biodiesel could kill two
turds birds with one stone, generating roughly seven billion gallons of fuel at just $3.11 a gallon. Conventional diesel costs about $3.00 a gallon.
The best practices for getting biodiesel this way have hardly been worked out yet, according to the study by EPA scientist David Kargbo. Among the biggest problems is finding a way to collect sludge that is high in lipids — the material the reaction uses — ensuring that traces of pharmaceutical chemicals don’t make it into the fuel. Finally, regulators haven’t even begun to assess what it would mean to transfer large amounts of sewage sludge to private companies for processing into biodiesel.
Via Science Daily