A Closer Look at Bioenergy, Biofuels, and Biomass

Bioenergy is an important renewable energy source that has gained popularity in recent years. But biofuels have been providing us power and keeping us warm ever since humankind kindled the first fire. Corn, sugarcane, barley, wheat, and even the wood in your fireplace can all be considered sources of bioenergy

In this guide, we’ll share what bioenergy actually is and how it can help us move towards greater sustainability

What Is Bioenergy?

Bioenergy refers to the chemical energy found within biomass or biofuels. That energy can be released through special processing, or simply by combustion. This leads us to our next two questions: What is biomass and what are biofuels? 

Biomass refers to organic material that at some point in its life cycle has benefited from photosynthesis and sunlight. Some examples include wood, crops, municipal waste, algae, and even grass.

Through photosynthesis, biomass contains within it stored chemical energy from sunlight, which is why we refer to bioenergy as renewable energy. Unlike fossil fuels, bioenergy inputs — or feedstocks as they are called — can be grown

While biomass is typically solid, biofuels are often liquid or gaseous, and represent a more refined (and more commercially viable) source of bioenergy. Biofuels can be sourced from a wide variety of feedstocks, and are more often used in transportation fuels thanks to their ability to be stored as liquid fuels

What Is an Example of Biomass?

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Wood is by far the most common source of bioenergy, and it’s the biomass that we humans have the most experience as a biofuel. By burning wood, we take advantage of the heat generated by the release of the sun’s chemical energy. That heat can cook a meal, keep us warm during a cold night, or perfectly roast a marshmallow

Commercial bioenergy operations are a good deal more sophisticated than your average backyard fire pit. Wood-fired bioenergy plants often burn wood that has been processed into wood pellets. These wood pellets are denser than your average log, and as a result they have a higher energy density.

Wood pellets are also often formed from the byproducts of logging operations, so while the timber you might find at your local hardware store needed to be sourced in one piece, wood pellets can be formed from wood chips and sawdust

What Are Examples of Biofuels?

Biofuels are typically more refined products than biomass, and they come from a wider variety of energy sources. Biofuels are often grouped into two categories: first-generation biofuels and second-generation biofuels. Let’s take them one at a time

First-Generation Biofuels 

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First-generation biofuels are typically sourced from food crops. The three most common types of food crop-based biofuels are sugarcane, soy, and corn

These crops are processed, often using fermentation at a commercial scale, and their sugars, starches, or oils are converted into biofuel

Brazil is the world leader when it comes to sugarcane-based biofuels, while the United States focuses almost entirely on corn-based biofuels. In both cases, crops that would typically be grown to feed people are instead diverted to energy use

Second-Generation Biofuels

Also referred to as advanced biofuels, second-generation biofuels are produced from biomass that isn’t sourced from food crops, and often isn’t grown on arable land

These advanced biofuels have an important advantage over corn-based or sugarcane-based biofuels because they don’t compete with food crops for the land they need to grow. Often, second-generation biofuels use grasses or trees grown on marginal land

How Is Bioenergy Used In Transportation Fuels?

Bioenergy is used outside of power plants — it’s often used as a transportation fuel, or as an additive in a transportation fuel. We’ll look at the three most common types of bioenergy liquid fuels

Biodiesel 

Biodiesel is created from vegetable oils or used restaurant grease, and it can be used to power engines specially designed for the purpose. Biodiesel isn’t widely used, but it does represent important renewable bioenergy

Interestingly enough, Rudolf Diesel — the inventor of the Diesel engine — experimented with biodiesel all the way back in the late 19th century. It may not have been as big a commercial success as his engine, but biodiesel has clearly been a source of interest for many years

Biogas 

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Biogas is another sustainable bioenergy source, and it’s created by putting food or animal waste through a special process called anaerobic digestion. Simply put, waste is placed in a container and deprived of oxygen. After a process of fermentation, a mixture of methane and carbon dioxide is created, which can be compressed into transportation fuel or used as a substitute for natural gas

Ethanol 

In the world of bioenergy, ethanol is created by processing the sugars from crops like sugarcane, barley, or corn. This ethanol is then blended into gasoline, making it a transportation fuel

Here in the United States, corn is both abundant and relatively inexpensive, making it an ideal candidate for biomass fuel. This ethanol is then blended into gasoline, making it a transportation fuel

Cellulosic ethanol is a newer, more advanced form of bioethanol. This biofuel uses the cellulose found in grasses and trees as a feedstock. Cellulosic ethanol has considerable appeal for its ability to be sourced from marginal lands, but it has struggled to be cost-competitive with other transportation fuels to this point

What Are the Advantages of Bioenergy?

The single biggest advantage of bioenergy is the fact that it is a renewable energy source, unlike fossil fuels that have a limited supply and will eventually run out

The sustainability of bioenergy is especially apparent with biomass products like wood. It’s easy to understand why: if you plant a tree for every tree cut down to make pellets for biomass-fired power plants, you’re essentially creating a renewable energy source

If biomass combustion is paired with responsible forestry, it can be thought of as a relatively green, renewable energy source. In the European Union, many countries are using biomass power plants to help meet emissions targets set to help combat climate change. In fact, the EU obtains a whopping 60% of its renewable energy from biomass sources

The use of bioenergy also has some important strategic advantages. Countries know that if they have the land to grow the biomass needed to run bioenergy power plants or to create transportation fuels, then they’ll have a relatively secure supply of domestically-grown power

That security of supply is one reason why the United States actively supports bioenergy through the Renewable Fuel Standard program, which mandates the production of biofuels. The Renewable Fuel Standard has helped the United States grow its bioenergy production and consumption by leaps and bounds since its creation in 2005

What Are the Disadvantages of Bioenergy?

One of the biggest problems with bioenergy is its relative lack of energy density. Compared to coal, natural gas, or even nuclear power, biomass fuels don’t produce much power or heat for their size

That means that scaling up bioenergy production requires a lot of land to grow the biomass necessary for energy production. If the biomass fuel is a first-generation biofuel (for example, corn in the United States), we end up with a lot of land and growing a lot of food that could otherwise be devoted to feeding people. There is some evidence that, because of this, biofuels are actually leading to a rise in global food prices

Some environmentalists worry that devoting more of our land use towards a few select crops for the purposes of creating bioenergy can harm biodiversity in the regions where these crops are grown

The environmental impacts of bioenergy can also be called into question. It’s true that bioenergy is a renewable energy source, but depending on the energy crops and the bioenergy technologies being used, greenhouse gas emissions rise well above the levels set by other low-carbon renewable energy sources like solar or wind power

In fact, burning biomass like wood produces carbon dioxide emissions, just like fossil fuels

The Future of Bioenergy

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Bioenergy comes in many different forms, from biomass like wood to first- and second-generation biofuels. Depending on the bioenergy system being discussed, the environmental impacts of bioenergy can range from nearly carbon-neutral all the way to heavy greenhouse gas emissions

Renewable energy sources are vital to lessen our reliance on fossil fuels, but it’s clear that they aren’t all equally qualified to help with climate change mitigation.

As modern bioenergy continues to incorporate new technologies, the use of biomass can become a greener energy solution that’s better for people and the planet.

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