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Biomass Energy- the Energy from Life Forms

Biomass Energy

Fire is among the oldest and one of the greatest discoveries made by humans. To be more precise, by the discovery of fire, we mean the first controlled use of fire by mankind. While we still don’t know exactly when the fire was discovered for the first time, the oldest evidence, ‘microscopic traces of wood ash’, of controlled use dates back to 1.7 million years ago. As the evidence suggests, the first fuel used to ignite fire was wood. When wood is still attached to a tree, it is alive, and dies when it is cut down, which makes it a life form. Life form, living or dead, when used as a fuel, is called biomass, and the energy generated, using biomass as a source, is the biomass energy. Taking everything aforementioned into consideration we reach to a conclusion that biomass was the first energy source to be used by humans, making biomass energy, the oldest energy form.

Biomass energy is organic energy since it is generated using materials that come from living organisms. Biomass is more often used as a raw material for making fuel, by getting converted into liquid biofuels or harvested as a gas from landfills, but in some cases, like wood, it is used as fuel itself. Biomass energy is renewable as life forms will never cease to exist. The best example to explain biomass energy’s renewability is wood, which is also the most used biomass for energy generation. Unlike non-renewable sources of energy, wood can be found in abundance and can be replenished by replacing the tree cut down for wood with planting another one. The most intriguing thing about wood is that even after millions of years of human evolution and advancement of technologies, wood still remains the most widely used and the most important single source of renewable energy providing about 6% of the global total primary energy supply. Its easy availability made people severely dependent on it, so much so, that in late 18th century, during industrial revolution, wood started to become scarce owing to the massive deforestation carried out to produce energy for running machineries. That was the time when humans decided to shift to coal and other fossil fuels for energy production, which at that time were in abundance. But recent growing need for energy, diminishing fossil fuels, and the pollution produced by their combustion have made humans rediscover the use of wood and other biomass as sources of energy. Furthermore, to avoid repetition of the mistakes from the18th century, many laws have been made by countries for cutting down of trees.

There are many other biomass sources other than woods to generate energy. Wood, itself, is used in many different forms, like firewood, wood pellets, and wood chips, lumber and furniture mill sawdust and waste, and black liquor from pulp and paper mills, while other sources of biomass energy include agricultural crops and waste materials, for instance- corn, switchgrass, miscanthus and bamboo, biogenic materials in municipal solid waste like- paper, cotton and wool products etc., animal manure, human sewage, sewage sludge and landfill gas. The energy from these sources can be transformed into usable energy through direct or indirect means. It can be burned, can be used to generate electricity or converted into electricity itself or processed into biofuels. 

The most common way to generate energy is using biomass directly as a fuel by burning it. The other use of biomass is by converting it into biofuels, which is liquid or gaseous in nature. Based on the source of the biomass, we can divide biofuels into three categories. First generation biofuels- derived from food sources like sugarcane and corn starch, second generation biofuels- derived from non-food-based biomass sources such as perennial energy crops (low input crops), and agricultural/municipal waste, and third generation biofuels- derived from microalgae. To convert raw biomass into fuels different methods are use which can be broadly classified as chemical, biochemical, electrochemical and thermal.

Under chemical conversion, raw biomass is converted into fuels using a range of chemical processes, such as the Fischer-Tropsch synthesis, a process in which biomass is converted into carbon monoxide and hydrogen which further are converted into synthetic fuels. In biochemical conversion biochemical processes of nature are used to break down the molecules of which the biomass is composed. In most cases, microorganisms are used to carry out the conversion process like, anaerobic decomposition in which bacteria break down material in absence of oxygen. This process is used in landfills to decompose biomass and produce methane. Electrochemical conversion converts biomass directly into electricity by electrochemical oxidation of the material in a fuel cell. Thermal conversion, as the name suggests, uses heat to upgrade biomass into a better fuel by methods like- pyrolysis, in which biomass is heated to 200°C to 300°C in absence of oxygen to produce fuels pyrolysis oil, syngas and biochar, and gasification- in which biomass is heated to 700°C with controlled oxygen to produce syngas and slag. These activities are carried inside dedicated places called biomass plants.

Biomass and biofuels are two of the best alternative energy sources to fossil fuels because of their renewable nature and low greenhouse emission. According to global bioenergy statistics, in 2017 renewable electricity covered about 25% of the electricity generated globally, out of which 596 TWh was produced using biomass as a source, making it the third largest renewable source after hydropower and wind. Today about 14% of the worldwide primary energy supply is provided by biomass resources — equivalent to 1000 million tons oil each year. A report from state that in early 2020, there were about 4,200 active biomass power plants worldwide, reaching an installed electrical capacity of around 72.5 GWel. India is one of top countries to use biomass as a source of energy.

Biomass energy is being promoted worldwide but its use has always remained a part of controversies because it is considered that increase in the use of biomass can lead to massive deforestation and increase the emission of harmful gases in nature. This leaves the future of the biomass in uncertainty. 

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