Energy from Biomass: Prospects and Challenges

Energy from Biomass: Prospects and Challenges

By Avanti Kulkarni

Fossil fuels are derived from plant and animal remains, trapped far beneath the surface of the earth for millions of years. Most of our contemporary energy demands are fulfilled by these fossil fuels. This has caused environmental and energy companies to divide and Given their harmful effects on health and the disastrous effects on the earth’s atmosphere, meeting our energy and fuel demands from a renewable carbonaceous source of energy like biomass is highly desired.

What Are Biomass Feedstocks?

Biomass feedstocks such as agriculture residues, energy crops, woody biomass, and municipal solid waste are all excellent sources of renewable fuel. Biomass feedstocks are categorized into two main feedstocks: starch/sugars, and the lignocellulosic biomass (forest and agricultural residue), namely. The selection of the conversion technology is dependent upon the type of feed stock. These technologies could be used to obtain various chemicals, liquid fuels and electric power.

How is Biomass Converted to Energy?

Biomass can be converted to energy by three ways: biochemically, through microbial fermentation and, lastly, via thermochemical processes. The biochemical approach includes digestion (aerobic and anaerobic) whereas the fermentation process takes place in the presence of microbes that convert the starch and sugar in feedstocks into liquid chemicals and fuels.

The thermochemical conversion platform, on the other hand, relies on thermal energy for conversion and includes pyrolysis, gasification, combustion and liquefaction processes. These thermochemical processes result in the production of an energy carrier in a liquid, solid or gaseous form.

Food Vs. Fuel Dilemma Favors Thermochemical Conversion Technologies

Fermentation of corn to produce ethanol for gasoline blending has been commercially successful. However, this has led to a food vs. fuel dilemma. To overcome the food vs. fuel debate, the biochemical conversion of lignocellulosic biomass has been proposed. However, extensive labor and capital cost make it an expensive process.

Relative to the biochemical platform, thermochemical conversion technologies have the benefit of being feedstock independent. Several different biomass species can be used after the pre-treatment and/or densification. In order to withstand natural calamities, the plant fiber structure and composition is made complex. The complexity leads to major challenges in the thermochemical conversion of biomass during several stages of the conversion process including biomass transportation, feeding, conversion and downstream clean-up. These challenges are further associated with a high cost. Extensive research is been conducted all around the world to address these issues and some have made significant progress in pre-treatment techniques, reactor design and catalysis of biofuel.

Why Biomass is Better

A major advantage of a biomass is that some agricultural crops (called energy crops) could help incorporate carbon and other inorganic nutrients back into the soil, thus making it a carbon negative renewable energy resource. Using biomass as an energy source can help reach the challenge of meeting the target of restricting the global temperature increase by 2 °C.

The United States is of the few countries that is aware of the potential value of biomasses and, thus, has an abundant biomass reserve. The Billion-Ton Study update, released by the Department of Energy in 2011, reported that the biomass supply in the US could be increased up to 1.1 billion dry tons by the year 2030 for energy production.

Image courtesy of pixabay.com

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