Biogas Production

UNDERSTANDING BIOGAS PRODUCTION

Biogas is a combination of methane and carbon dioxide that is produced through anaerobic digestion. The methane portion of the biogas, typically from 50-80% by volume, is very rich in energy and can be used within existing infrastructure. Methane is chemically identical to natural gas, but anaerobic digestion has a much more environmentally friendly lifecycle than fracking and biogas is sustainably produced from liquid wastes. The biogas can be burned directly in a number of commercially available generators and turbines or the methane can be purified and compressed for use in place of compressed natural gas.

Anaerobic digestion is a process by which a series of microbes break down organic material into biogas. Hydrolytic bacteria break down incoming material into free fatty acids, amino acids, and sugars; acetogen and acidogen microbes break down this material into acetic acid; and methanogens break down the acetic acid into methane and carbon dioxide. The final step, methanogenesis, is the rate limiting step of the process and an overload of energy will cause the system to crash. Other issues relating to microbial health and process flow are crucial in the development of anaerobic digestion systems or the use of high energy feedstocks.

Biodico specializes in biomethane potential testing and in the testing and implementation of high energy feedstocks for anaerobic digestion systems. We have worked with mesophilic and thermophilic microbial communities with a wide array of different process technologies and been able to substantially increase biogas production. We are also equipped with a state of the art biomethane potential test laboratory with two Automated Methane Potential Test Systems (AMPTS). Each AMPTS is able to simultaneously test 15 batch digesters for methane production (the CO₂ is scrubbed out) and provide production rate and cumulative production data every 15 minutes.

Glycerin is a very widely used substance with applications ranging from cosmetics to industrial manufacturing. The glycerin byproduct from biodiesel production is far from pure though. Producers’ grade glycerin is generally about 65% actual glycerin with the remainder made up of soaps, emulsified fatty acid compounds, water, and methanol. The biodiesel is produced through the transesterification of triglycerides and the free fatty acids produced briefly in the intermediate reactions, as well as any FFAs in the feedstock, react with the base catalyst to form sodium or potassium fatty acid soaps. Just as bathroom soaps cause body oils to mix with water in order to clean the skin, the soaps formed in this process cause an emulsification of the non-polar fatty acid compounds and the polar glycerin, resulting in an impure glycerin byproduct.

Biodico has worked extensively with the use of glycerin in anaerobic digestion and has been able to increase the biogas production from most standard feedstocks by 300-400%. Glycerin alone or in the wrong amount can easily crash a digester, but Biodico has refined the necessary concentrations and additives and currently works with commercial digesters and wastewater facilities to increase biogas production with its proprietary GBX formulation.