There is more than one way to get liquid fuel from bio-mass. We have covered cellulosic ethanol in an earlier SDU posting (here). Now we look at making a mix of various alcohols from almost any cellulosic material, including municipal solid waste and sewage sludge. By using these waste streams as the fuel feed stock, the MixAlco process can provide a large fraction of our fuel needs without displacing valuable crop lands or using high energy crops such as corn.
The MixAlco process converts biomass from any source into organic chemicals and alcohols via lime pretreatment; non-sterile, acidogenic digestion; product concentration; thermal conversion and hydrogenation. Because they have low capital costs and relatively simple operation, the MixAlco pretreatment and fermentation steps may be carried out on-location at sewage treatment plants or municipal landfills. Several studies have shown that MixAlco is capable of economically converting dairy manure and chipped yard waste into carboxylic acids which can be converted to alcohol.
Professor Mark Holtzapple, holder of many patents on this process makes a great presentation at Texas A&M on the MixAlco process and his Star Rotor engine which is currently under development.