Benchmark’s ethanol plants re-engineering includes incorporating an Anaerobic Digester to produce renewable biogas and generate 100% of the thermal energy required for processing the ethanol and the by-products. It eliminates the use of hydrocarbons from the process.
History of Anaerobic Digesters
The first anaerobic digester for biogas production was built in France in 1860; it was converted from a settling basin of a sewage system.
In 1925, a heated anaerobic digester was designed and built in Germany.
The first anaerobic digester in the United States was established in 1926 and the digester was operated with a temperature control system.
Significant effort was spent on aerobic digestion of organic waste materials for biogas production in Europe and the United States after World War II. However, relatively cheap petroleum had prevented anaerobic digestion for biogas production from becoming a major energy generation technology and a main source of thermal energy.
More than 5 million anaerobic digesters were built in China. Most of them small household scale and operated under ambient temperature. However, only a few anaerobic digesters in the United States and Europe were built for generating thermal energy.
In recent years, biogas production has again attracted worldwide attention and wide adoption as a renewable energy source because of sustainability goals and environmental concerns regarding fossil fuels, in addition to becoming cost competitive and enhancing domestic energy security.
More than 17,000 biogas plants were in operation in Europe by the end of 2014. These plants are producing biogas through anaerobic digestion from a variety feedstock material.
The United States currently only has 2,200 operating biogas systems, representing less than 20 percent of the total potential.
Benchmark designed Anaerobic Digester
For a 60 MGY ethanol production, Benchmark will build a 30-million-gallon Anaerobic Digester.
The new Anaerobic Digester is a proven Benchmark Design LLC technology and will operate at moderate controlled temperatures (30 C – 37 C). This temperature range is classified as a Mesophilic Anaerobic Process. These types of digesters are easy to start up, `have very stable performance and are relatively high in microbial activities.
One main feature and competitive advantage of Benchmark’s Digester is the control and uniformity of the proprietary feedstock used to generate the biogas in a mixed flow reactor. (Feedstock System and Process to Producing Biogas from an Ethanol Slurry Mix- Patent # 11,046,925)
Generally organic feedstocks used for biogas production (especially waste organic materials) may contain inhibitory chemical compounds that, at certain concentration, can cause anaerobic digestion upsets. Among the undesirable compounds commonly found in waste materials are ammonia, sulfide, and other metals.
Benchmark formulated feedstock is free of any of these inhibitory compounds, which constitute an additional level of safety for the uniform production of biogas. In addition, the proprietary feedstock to be utilized has been thoroughly tested in a variety of concentrations and optimization of performance and will result in a state-of-the-art Digester, with significant margins of safety in terms of biogas production volume required for full and continuous operation.
For additional information, please contact the company.
Note: Some of the information on biogas digesters was sourced from the book “Biomass to Renewable Energy Processes” authored by Dr. Jay J. Cheng, PhD, professor at NCSU Biological & Agricultural Department.
