By: Tina Casey
So who knew? The manufacture of cooking oil involves hexane, a solvent that separates the oil from crushed seeds. Hexane is a volatile organic compound found in gasoline. Hexane is also a degreaser used in the printing industry. It dissolves glues, varnishes, and inks. Aside from the ick factor of having the same compound used to dissolve glues and inks pop up in the production of your bake sale items, hexane is a pollutant that contributes to smog and greenhouse gas emissions.
This is where Queens University of Ontario, Canada comes in. Researchers there have discovered a new energy efficient way to use the greenhouse gas carbon dioxide to help separate oils from seed and vegetable crops including corn, canola, peanut safflower, sunflower, and soybean. That’s the sustainable twofer we’re so fond of: a new twist on a conventional process that reduces negative impacts while providing a remedy for additional problems as well.
Cooking Oil and Hexane
As part of a broader effort to reduce hexane emissions (pdf), the U.S. EPA introduced new rules for hexane emissions from seed crushing facilities in 2002. For the most part, hexane is recycled and reused within these facilities, so the emphasis was on reducing – though not entirely eliminating – the relatively small amount that escaped the process. However, as world populations grow and demand for cooking oil rises, even small amounts will begin to climb.
Cooking Oil, Carbon Dioxide, and Energy Efficiency
The Queens University process addresses three issues with conventional cooking oil production. First, it completely eliminates hexane. Second, it puts our planet’s overabundance of carbon dioxide to good use. And third, it eliminates the need for distillation, which is an energy-gobbling part of the conventional process. The researchers discovered that oil can be extracted from soybeans by adding carbonated water to a mixture of soybeans and an alternative solvent. No distillation is needed, and both the water and the solvent can be used again. At this point, the process is not commercially viable, partly because it is far more expensive than the hexane-based method. The researchers’ ultimate goal is to bring the cost down to a competitive level.
Creative Uses for Greenhouse Gasses
Compared to carbon sequestration, the productive use of excess carbon dioxide is a mighty attractive way to reduce greenhouse gas emissions. Cooking oil manufacturing is one example. Another can be found in biofuel production, where the company Joule Technologies has developed a way to grow biofuel-producing organisms with carbon dioxide and sunlight. It also dovetails with the “green chemistry” trend of developing new sustainable process that eliminate the use of hazardous chemicals, for example by using kinetic energy to disinfect water instead of using chlorine.
Image: Cooking oil by Rene S on flickr.com.