Biomass Energy 101

How Is Biomass Energy Generated?

Biomass contains sun-generated chemical energy. For example, a plant will produce biomass via the process of photosynthesis. It is also possible to burn biomass and generate for heat or turn it into a renewable fuels with the help of a number of different procedures.

Some of the main sources of biomass refer to:

• Wood and the resulting waste obtained from processing wood, including wood chips, pellets, firewood, mill sawdust from furniture and lumber waste, and even black liquor obtained from paper mills. Black liquor is a by product of paper production procedures and it can also be used as an energy source once it is pulled out of the digesters when the pulp of the wood is removed. Once it evaporates, it turns into a substance that resembles black liquor which can be burned and used as fuel in recovery furnaces.
• Animal manure
• Human sewage
• Crops from agriculture and waste materials such as algae, corn, sugar cane, soy beans, woody plants or switchgrass
• Residues that result from food processing processes
• Wool products, paper, yard, food, cotton and wood waste and other biogenic materials found in solid waste

In other words, biomass is a wide term that can incorporate anything from plant, animal, wood, or agricultural waste sources. When it comes to the biomass energy is generated, biomass is usually used in the form of wood pellets that need to be harvested from a forest and burned in order to generate energy.

Given the need to drastically reduce the number of coal-based power plants around the world because of the climate change problems we are facing today, biomass energy is gaining more and more popularity as an alternative source of generating power.

It is also possible to use biomass in an indirect manner, by turning organic matter into biofuel that can be used as carriers of energy to conventional fuel like petroleum or diesel. Biomass energy represents as much as half of all renewable energy generated in the United States alone, according to data from the U.S. Energy Information Administration. Fifty percent of it generated with the help of wood products.

Biomass can be turned into energy using a number of different procedures, such as:

• burning or direct combustion in order to generate heat
• chemical conversion that can generate liquid fuel
• thermochemical conversion that can generate liquid, solid, and gaseous fuel
• biological conversion that can generate gaseous and liquid fuel

Direct Combustion

As stated previously, the most common method of generating energy with the help of biomass is direct combustion. All types of biomass can be burned and used to provide water and heat to buildings, generate heat at an industrial level or generate electricity with the help of steam turbines.

Thermochemical Conversion

The thermochemical conversion of biomass uses gasification and pyrolysis, which are two similar procedures that rely on heat-based decomposition in which biomass from feedstock is heated in an enclosed and pressurized vessel at a high temperature. 

When it comes to pyrolysis, organic materials need to be heated to 800–900°F without having to use any oxygen. Biomass pyrolysis generates hydrogen, charcoal, renewable diesel, bio oil and other forms of fuels.

Hydrotreating

With the help of hydrotreating, experts can process bio-oil with the help of hydrogen subject to high temperatures and levels of pressure with a catalyst that can generate renewable jet fuel, diesel, and gasoline.

Gasification

Gasification is the process of heating organic materials to temperatures between 1,400 and 1700°F  free oxygen injections or steam into the vessels in order to generate a gas that contains large amounts of hydrogen and carbon monoxide. This is called a syngas and it can play the role of fuel used with a diesel engine, to heat a building, or to generate electricity for gas turbines.

Biological conversion

With the help of biological conversion such as fermentation, biomass can be turned into ethanol as and generate natural gas that is renewable (called biogas). Ethanol can be used to fuel vehicles. Biogas is generated in landfills with solid waste, as well as anaerobic digesters found at sewage treatment plants and livestock or dairy operations. Biogas that has undergone the correct treatment can be used similarly to natural gas based on fossil fuel.

At the moment, researchers are continuing their work towards finding the best solutions of improving all of these processes and developing additional ways of converting and using even more biomass to generate energy.

Is Biomass Energy Renewable?

This is one popular question often times asked in relation to the use of biomass. Scientists who have long studied the main biomass energy facts claim the following: since trees that need to be cut to generate bioenergy will grow back, this means that this particular source of energy is inherently renewable. The same goes for waste and manure whose availability is not expected to lower compared to the limited amounts of fossil fuels.

However, there are also voices that claim that because of the environmental impacts in the form of tree harvesting, fine particles and emissions resulting in the burning process, or the need to remove large forest areas in order to generate feedstock, biomass energy might not be as advantageous.

Biomass Energy Advantages and Disadvantages

Advantages

• Biomass is constantly available worldwide and it is considered a renewable energy source.
• Organic materials needed to generate biomass are not finite, since the planet continuously produces manure, wood, garbage and other forms of waste.
• Biomass is carbon neutral, as it only releases the same amount of carbon as the amount that was originally absorbed by the plants during their life cycle.
• Biomass is more affordable than fossil fuel energy as there is no need to drill for oil or build pipelines to collect the fuel.
• It helps us use smaller amounts of polluting fossil fuels that release large amounts of CO2.
• Landfills are emptied out for waste and garbage by as much as 90%.

Disadvantages

• Energy generated by biomass is not as efficient as fossil fuel energy.
• Biomass is not 100% clean given the need to use human and animal waste which will in turn generate methane gas which is harmful for the environment. Wood burning is another polluting process, similar to coal burning.
• Biomass energy could lead to serious deforestation issues in the future.

With further research in the field and more innovation that will make biomass more easily available and affordable, biomass energy could become a serious candidate that could replace conventional energy sources.