Biomass Energy

What is Biomass Energy?

Biomass energy is an organic energy generated or produced by living or once-living organisms. Biomass feedstocks are the materials used to generate this energy. Some examples of biomass feedstocks are switchgrass, wheat, sunflowers, cottonseed oil, soy, jatropha, palm oil, sugar cane, canola, and corn. Although biomass is an organic energy, it can also be a non-renewable energy. The energy is obtained from the sunlight that the biomass feedstocks gains. The energy is than directly burned (creating heat) or converted into electricity. It can also be indirectly processed into biofuel [1].

What are the Advantages?

• Clean and renewable energy source [1]
• Initial energy comes from the sun
• Biomass materials can regrow in a short time period
• If trees and crops are sustainably farmed, they can offset carbon emissions by absorbing carbon dioxide through respiration
• Biomass feedstocks can be harvested on marginal lands or pastures (not competing with food crops)
• Energy is stored within the organism and can be harvested when needed

What are the Disadvantages?

• If biomass feedstock is consumed more than its reproduces, it can become a non-renewable resource [1]
• The land that grows crops (corn, soybeans, etc.) used for biomass cannot be used to grow other foods or create habitats for animals
• If forested areas are not sustainably cut, replanted, and given time to grow and sequester carbon, the advantages of using wood for fuel are not offset by the tree’s growth
• Biomass plants require the use of fossil fuels to be economically efficient which interferes with sustainability
• If the gases that are created when burning biomass are not captured and recycled properly, it can create smog and exceed the number of pollutants released by fossil fuels

Ways to turn Biomass Energy into Heat

Thermal Conversion

Biomass feedstocks are heated so they can be burned, dehydrated, or stabilized. This method is commonly used on raw materials (e.g. municipal solid waste (MSW), scraps from paper or lumber mills) [1].

Torrefaction

The chemical process that dries the biomass before it can be burned. The material is heated to 200°C to 320°C. Torrefaction dries the biomass so that it cannot absorb moisture or rot while still retaining 90% of its energy. The lost energy can be used to fuel this process. The dried-out materials are compressed into briquettes (small, molded block of charcoal or biomass) [1].

Direct Firing

When the briquettes are burned directly. The steam produced powers a turbine which turns a generator and produces electricity [1].

Co-Firing

When biomass is burned with a fossil fuel. This process commonly occurs in coal plants. This process also eliminates the need for new factories for processing biomass as well as the demand for coal (reducing carbon dioxide and greenhouse gas amount from fossil fuels [1].

Pyrolysis

When biomass is heated without oxygen. This process keeps it from combusting and causes the biomass to be chemically altered. Pyrolysis produces a dark liquid called pyrolysis oil (synthetic gas called syngas) which is a type of tar. The oil is currently being studied as a possible alternative for petroleum. Biochar is also produced from pyrolysis. Biochar is a type of charcoal that is rich in carbon and extremely useful in agriculture. It enriches the soil and prevents it from leaching pesticides and other nutrients into runoff [1].

Gasification

When the biomass is heated with a controlled amount of oxygen letting the molecules break down and produce syngas (combination of hydrogen and carbon monoxide which is used for heat, electricity, or processed into transportation biofuels, chemicals, and fertilizers) and slag (glassy, molten liquid used to make shingles, cement, or asphalt) [1].

Anaerobic decomposition

Microorganisms (usually bacteria) break down material in the absence of oxygen. When the biomass decays, it produces methane (an energy source). An anaerobic environment is where there is a lack of oxygen [1].

Biofuel

Biomass is the only renewable energy source that can be converted into liquid biofuels such as ethanol and biodiesel. Biofuel can be used to power vehicles [1].

Black Liquor

Wood is processed into paper, creating a high-energy, toxic substance. It can be recycled and used to power mills [1].

Hydrogen Fuel Cells

Biomass is rich in hydrogen which can be extracted and used to generate power and fuel vehicles. Currently, hydrogen fuel cells are used to power buses, forklifts, boats, submarines and are being tested on airplanes and other vehicles [1].

Next Steps in Research to Advance Biomass Energy

Growing Energy Plantations

It only takes 3 – 15 years to grow trees that are suitable to be converted to bioenergy unlike trees that are grown in natural forests which can take 40 – 100 years to mature. This type of plantation also offers substantial supply cost reductions as well as a possibility of providing landowners and farmers with additional cash crop [4].

Testing A Variety of Fast-Growing Poplars

“A program in eastern Ontario is demonstrating that hybrid poplars from genetically improved stick could be established and grown to produce biomass on a sustainable basis.” [3]. When harvesting biomass from energy plantations, European machinery that has been modified has worked most effectively [4].

IEA Bioenergy

Canada is participating in research activities with the International Energy Agency (IEA) Bioenergy who has a focus of improving and sharing information between countries relating to bioenergy research, development and deployment. There is a study that is focused on the “sustainability of forest residues for bioenergy production as well as the potential effects on land use of changing over to enhanced bioenergy production.” [4].

How Engineers Use Biomass Energy Relating to Transportation

Transporting high bulk volume of biomass can result in high expenses, the use of large storage facilities, and having to have a high moisture content which can result in biological degradation and freezing and blocking in-plant transportation systems [2]. “All of those problems may be overcome by standardization and densification. The former consists of processing the original biomass in order to obtain fuels with standard size and heating properties, while the latter consists in compressing the material, which needs to be available in the sawdust size, to give it more uniform properties.” [3].