Table 2.
Modern bioenergy conversion technology summary
| Category | Products | Technology |
|---|---|---|
| Non-biological | ||
| Combustion1 | Electricity, heat | Mature. Electricity generation rather capital intensive (about $1,900 - $4,300/installed kW). |
| Gasification2 | Electricity (via gas turbines) or synthetic gasoline and diesel (e.g., Fischer-Tropsch) | Limited commercial application. Often highly capital intensive (about $375/L annual capacity for coal liquefaction in South Africa). |
| Pyrolysis3 | “Biocrude”, a mixture of liquid-phase organics | Limited commercial application. $2/L annual capacity for production of naptha and diesel. |
| Pressing and transesterification4 | Biodiesel from oil-rich crops | Mature. Relatively simple, low capital ($0.33/L installed capacity for biodiesel in Europe). |
| Biological | ||
| Fermentation of starch and sugars | Ethanol, potentially many other molecules | Mature for ethanol production. Capital cost5 about $1.20/L installed capacity for ethanol with cogeneration in Brazil, about $2/L installed capacity for maize ethanol in the US. |
| Anaerobic digestion | Methane | Rather mature. Can be applied to both liquid and solid wastes. Many thousand small-scale digesters operative, particularly in China and Germany. |
| Lignocellulose hydrolysis and fermentation | Ethanol, potentially many other molecules | Not mature. Hydrolysis can be accomplished via acid or enzymes. Several fermentation options and configurations. |