„Ethanol is a quasi-renewable energy source because while the energy is partially generated by using a resource, sunlight, which cannot be depleted, the harvesting process requires vast amounts of energy that typically comes from non-renewable sources. Creation of ethanol starts with photosynthesis causing a feedstock, such as sugar cane or a grain such as maize (corn), to grow. These feedstocks are processed into ethanol. … Bio-ethanol is usually obtained from the conversion of carbon-based feedstock. Agricultural feedstocks are considered renewable because they get energy from the sun using photosynthesis, provided that all minerals required for growth (such as nitrogen and phosphorus) are returned to the land. Ethanol can be produced from a variety of feedstocks such as sugar cane, bagasse, …, straw, cotton, other biomass, as well as many types of cellulose waste and harvesting, whichever has the best well-to-wheel assessment.”
cited from: Ethanol fuel. (2014, September 7). In Wikipedia, The Free Encyclopedia. Retrieved 07:36, September 12, 2014, from http://en.wikipedia.org/w/index.php?title=Ethanol_fuel&oldid=624550092
EnviCare® Engineering GmbH was able to obtain all regulatory approvals for the construction of a bioethanol plant, which process steps are briefly described below.
A concept for a higher efficiency
This plant for the production of about 500,000 l / year bioethanol complements the material and energy balance of a conventional 500 kW biogas plant. It optimises the whole concept as not only the waste heat from the CHP but also the slop of the bioethanol plant can be usefully exploited in the biogas plant.
All commodities are being used
In the bioethanol plant the agricultural commodities corn and wheat grains are processed while the plant without cobs is fermented in the biogas plant. The raw material is first miled and then pumped into the slurry tank.
Processing and distillation
In the mingle tank a protein-rest is kept at a certain temperature, simultaneously the enzymatic conversion of the starch begins. In the fermenter the mash is mixed with the yeast. The fermentation tank is cooled to control the temperature during the fermentation. After a certain time the alcohol quantity is in the range of about 10-12%. The distillation system consists of a mash column, a rectifying column and a dephlegmator. The task of the mash column is to expel the alcohol and feed it vaporous into the directly patched rectification column for further concentration.
Extraction of the targeted outputs
With a sump pump the mash in the column bottom is continuously moved and heated. In the accumulator, the fusel oil is excreted and then separated in the fusel oil separator. Over that the dephlegmator is placed, in which the warm fermented mash from the fermenter is fed in counter-current and preheated. In return, the alcohol is concentrated to about 94% and thereby cooled.
Energetical use of residues
The finished raw alcohol is condensed in the heat exchanger and passes into the ethanol reservoir. The stillage is fed to the biogas plant.