In standard production of ethanol, enzymes are used to break down the biomass and release sugars. (sciencedaily.com)
During the first global oil crisis in 1975, Brazil launched a national biofuel programme leading to the large - scale production of ethanol from domestic sugar supplies. (greenfacts.org)
As a result, the energy recovered in the ethanol so produced is less than that required to produce it, i.e., there is a negative energy balance (more production of ethanol imposes more load on the environment). (sciencedaily.com)