Utilization of bioenergy

Bioenergy is a field that relates to various processes and applications, because it very often has a very large. This field can concern the production of energy through direct biomass combustion, the use of gas fuels, liquid biofuels, and the use of microbial populations to produce biohydrogen or for waste treatment. Here is an explanation of each of these applications.

Direct biomass combustion

Biomass can be directly burnt in order to produce heat. This is the most basic application of bioenergy, and is the most widespread bioenergy technology. The use of biomass as a heating source, however, can sometimes be more complex than the simple burning of wooden logs. In the past years, wood and herbaceous pellets as well as briquettes have become popular means to create more efficient fuels that can be, in certain regions, less harmful to human health than the direct combustion of biomass.

Gas fuels

Through pyrolysis or gasification processes, it is possible to produce fuels from solid biomass. This results into a cycle with a higher thermal efficiency. The first step is a pyrolysis phase (heating of organic matter), which forms a solid char, a liquid fraction and volatile gases. All three fractions can be used independently or further processed. In the creation of syngas, the volatiles and part of the char react with oxygen to create carbon monoxide. The char further reacts with carbon monoxide to create the gaseous fuel called syngas, a mix of dihydrogen and carbon dioxide. This gas can then be used as a fuel for burning and for electricity generation. Biofuel greenhouse heating project

Another way to produce useful gas fuels is through anaerobic digestion of solids or liquids. In the absence of oxygen, microbial populations will generate biogas (a mixture of methane, carbon dioxide, sulfur oxides and water vapour) by digesting organic matter from waste or energy crops. This gas can then be used to produce either heat, electricity or both.

Dr. Jeff Bergthorson conducts important research on the combustion and reformation of sustainable fuels, such as synthetic gas (a mixture of dihydrogen and carbon monoxide), that can be used as alternatives to fossil fuels. His research group, the Alternative Fuels Laboratory, runs experiments in order to build detailed models related to the combustion of such fuels and to optimize the process.

Dr. Mark Lefsrud is conducting experiments on the gasification of certain biomass products as a potential value-added feedstock for the purpose of heating greenhouses. He also leads the Biomass production lab, which currently focuses on community proteomics for the production of liquid biofuels.

Liquid biofuels

Liquid biofuels are usually classified in 2 categories: biodiesel and ethanol. Biodiesel is usually made with vegetable oils or other feedstocks with a high lipid and oil content. The transesterification process generates a less viscous liquid with a relatively high heating value that can be used in diesel engines. It provides lower fine particle counts in the exhaust and is generally considered an extremely "clean" feedstock for a diesel engine.

Ethanol is usually produced through the fermentation of certain organic materials under the action of microbial populations or yeasts. It is a good alternative to highly-refined liquid fossil fuels and can replace them in biofuel designed or modified combustion engines.

The utilization of biofuels is currently investigated for its applications in motors and other engines, as well as its effects on the expected life of combustion engines that work with blends of liquid biofuels and conventional fossil fuels.

Biological treatment of waste

Membrane bioreactors (MBR) have been used for decades as a good secondary treatment option in small municipalities for wastewater treatment. The use of aerobic or anaerobic microbial populations that feed on nutrients allows the treatment of suspended solids through membrane filtration. Membrane bioreactors have been added to increase the water treatment capacity of the Olympic village for the 2008 Beijing Olympics and to recycle 50% of the wastewater. The use of MBR treatment and other technologies has more than doubled the water treatment capacity of the Beixiaohe wastewater treatment plant by using a biological energy source.

Microbial populations can also be used to treat solids. Composting of organic matter, is one of the best ways to reduce solid waste volumes. Large composting facilities can make an odorless product from organic waste. Treatment under high temperatures has the ability to kill parasites and weeds that could be found in the initial waste. The method of industrial composting is an efficient method used by cities like Edmonton or Toronto in order to reduce the waste mass that needs to be transported to landfills.

Dr. Dominic Frigon works on the application of mathematical models to microbial populations for waste treatment systems and plans to work on the development of hydrogen and microbial fuel cells.

Bioproduction of hydrogen

Hydrogen can be produced by either photosynthetic or fermentative microbial populations.

Researchers discovered that under sulfur deprivation, cells from microalgae Chlamydomonas reinhardtii could produce molecular dihydrogen by a transfer of protons and electrons during a biophotolysis process, a chemical reaction in which the compounds break down under the action of photons. In a sulfur-lacking environment, Chlamydomonas reinhardtii accumulate starch and have an increased consumption of oxygen which leads to the degradation of water molecules to consume the oxygen atom and the release of dihydrogen. Sustained dihydrogen production can be attained in the absence of acetone and is dependant on the lighting at certain stages (there is an aerobic phase followed by an anaerobic phase in the absence of ambien oxygen), pH, the possible addition of sulfur as well as the use of mutant microalgae.

Indirect biophotolysis refers to a fermentation process under which purple, non-sulfur photosynthetic bacteria use sugars as a feedstock to produce dihydrogen and carbon dioxide in a nitrogen-deficient environment. Like direct biophotolysis, this process requires an energy input provided by photons.

Dark fermentation, on the other hand, uses organic matter as the primary feedstock. Under anaerobic conditions, the digestion of the substrate will yield dihydrogen gas, but also different acids and alcohols, such as ethanol or methanol. The yields in biohydrogen depend on the microbial populations, oxidation state, the primary feedstock, and the environmental conditions. Dark fermentation yields a lot of by-products, but does not require any light and can work with a wide array of feedstocks.

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