What is Biomass Energy and How Does it Work?
Biomass energy is organic matter that can be burned or decomposed to be used a source of energy. In a way, biomass energy is a form of solar energy since it receives its original energy from the sun by photosynthesis. This solar energy is stored in plants and is available for conversion into usable forms of energy.
Biomass energy comes in many forms. These include burning wood, converting waste into energy, collecting methane for biogas, and using energy crops for biofuels.
When most people hear the term “renewable energy” they usually think of solar panels or wind turbines, but biomass actually accounts for most of our renewable energy consumption in the US. Most of this is through wood burning and biofuels such as biodiesel and ethanol.
Biomass energy is renewable because we have a boundless capacity to grow plants, and in turn we will always produce biomass waste with those plants.
Collectively, biomass energy lessens our dependency on foreign oil, strengthens our economy both locally and nationally, reduces harmful greenhouse emissions, and will hopefully contribute to the phasing out of fossil fuels altogether someday.
Let’s go over each of the biomass energy sources.
In fact, wood was the main source of energy across the planet until fossil fuels took over in the mid-1800s.
Today, we still use wood for heating and cooking (especially in developing countries), but most of it is for industrial purposes.
Wood can be burned for electricity production by using the heat to create steam for spinning turbines. Some manufacturing plants even burn their own wood waste (paper, wood scrap, wood chips, sawdust, and bark) to contribute to power needs.
Garbage and waste from landfills can be used as an energy source. About half of the waste in our landfills contains organic biomass matter that can be converted to energy. This content is sometimes called biogenic matter. All biogenic matter contains potential energy.
Paper, grass clipping, cardboard, wood, and food scraps are all good examples of biomass energy sources.
We create an incredible amount of waste. In fact, it’s estimated that an average American produces about 5 pounds of waste every single day. This all adds up quickly in our landfills if the waste isn’t properly managed.
There are a few things we can do with this waste. One option is to just simply burn it in solid waste incinerators and be left with compacted ash which takes up less space.
Granted, this is in indeed an effective means of reducing the quantity of waste, but what about all the organic matter that contains usable energy?
A better alternative is to put the waste to good use in a Waste-to-Energy Plant. These plants can make use of heat energy by burning waste to produce steam which spins turbines to generate electricity.
Currently, waste-to-energy plants provide about 15 million kilowatt-hours. This is enough electricity to power around 1.5 million homes.
Not only can we reduce waste in our landfills, but we can also use it for our own energy needs.
Waste-to-Energy plants still cost more than other standard electricity production methods, but as technology continues to improve this will not be as much of an issue. Also, one could argue the benefits of cleaning up our landfills makes it worthwhile, not to mention further reducing our need for fossil fuels.
Biogas comes from microorganisms that digest (break down) organic waste which becomes a mixture of methane gas and carbon dioxide. This is called anaerobic digestion.
On farms and sewage treatment plants, manure and human waste is a good source of biogas. An anaerobic methane digester traps large amounts of waste with limited oxygen and high temperature to induce bacteria into breaking it down – or digesting it. Obviously, the inherent odor can become an issue if the digester is too close to a residential community.
Biogas contains a much lower percentage of methane than standard natural gas. To reach standards necessary for practical use, biogas has to be “upgraded”.
Depending on the use, methane levels are increased and carbon dioxide levels are decreased before it can be used. Certain things, like boilers, don’t require high quality biogas. On the other hand, when used as a fuel source biogas quality must reach a much higher standard.
Essentially, it is a renewable natural gas which can be substituted for the more common natural gas found deep within the earth. It can be used for any purpose that already uses natural gas such as heating, cooking, lighting, steam production, electrical production, and can even be used as an alternative fuel in natural gas vehicles.
Biofuels such as ethanol and biodiesel can be used as clean fuel sources for vehicles of every sort.
They are usually blended with standard fuels as “green” supplement, but they can also be used on their own in specialized vehicles.
Biodiesel is made from organic materials such as animal fat, recycled grease, and vegetable oil. It’s renewable, nontoxic, biodegradable, clean, and safe.
Biodiesel is made by separating biomass into fatty acid methyl esters (FAME) and glycerin. The methyl esters are what make up the biodiesel. The glycerin is a byproduct that can be used in cosmetics, pharmaceuticals, soaps, and food additives.
Most of the biodiesel production source comes from businesses that already use animal fats or vegetable oils in their product.
An appealing aspect of biodiesel is that it’s compatible with most diesel engines. It can be blended with regular diesel in any amounts with no modifications needed to the engine.
Specific labels are used to indicate the ratio of biodiesel used. For example, B20 contains 20% biodiesel and 80% petroleum diesel. B100 contains 100% biodiesel.
B100 can be used with some newer engines (1994 and newer) although there are some drawbacks. The higher the amount of biodiesel, the more likely it is to freeze in colder temperatures since it has a higher freezing point than petroleum. The freezing point depends on the source product used. For example, canola oil has a much lower freezing point than tallow (animal oil).
Nitrogen oxide emissions are higher in biodiesel, but many more harmful emissions are avoided. It can be harder on rubber engine components, and you can expect gas mileage to be about 8% lower. Only engines that use the highest quality biodiesel and are specifically equipped to handle these limitations should use B100.
B20 is the by far the most popular biodiesel mixture and can overcome most of the limitations of the B100. It can withstand cold weather, and is much easier on certain engine components.
Obviously, the higher the blend, the better it will be for the environment and public health. It’s also less combustible and safer if there is ever any kind of spill.
Ethanol, also known as grain alcohol, is a liquid fuel made from energy crops such as corn and sugarcane. When these crops undergo yeast fermentation they release ethanol. It can then be used as a transportation fuel source for automobiles.
The very first automobiles ran on ethanol. In fact, Henry Ford even claimed it to be “the fuel of the future”. Eventually gasoline took over the market because of its superior fuel efficiency (ethanol is 34% less energy efficient than gasoline) and cheap production costs.
Most of the cars in the US are capable of running on a blend of ethanol, usually up to 10%. More than half of all gas stations now add ethanol. In some states, it’s even required by law to have ethanol added to gasoline. Recently, more flex-fuel cars are coming into the market. Flex-fuel cars are capable of running on E85 fuel (85% ethanol, 15% gasoline), gasoline by itself, or a combination of the two.
The most common crop used for ethanol production in the US is corn. In Brazil (the second largest ethanol producer), sugarcane is the crop of choice.
It doesn’t necessarily matter what the source crop is, the ethanol will always be the same and of the same quality. The main factors in determining which crop to use are availability and cost. Certain crops grow more readily in different parts of the world.
Much research is going into finding alternative sources of ethanol and ways to grow these crops faster and cheaper. The quality of the crops isn’t as much of a concern since they aren’t used for food.
Other ethanol crops include potatoes, sorghum, sawgrass, and barley. Also, certain cellulosic feedstock like wood, grass, newspaper, crop residues, and nonedible portions of plants can be used. These cellulosic crops are more difficult to produce ethanol from since they must first break down into simple sugars before they can be fermented.
There are many benefits of using ethanol fuel. It reduces our dependence on foreign oil (ethanol is produced domestically) and reduces harmful greenhouse gas emissions. It strengthens the agricultural industry, and creates renewable energy jobs.
Ethanol is biodegradable, so if there’s ever a large spill it will pose little threat to the environment or public health. Also, the price of ethanol is always decreasing because of technological improvements in production and greater consumer demand for cleaner fuels.
Ethanol has the same chemical makeup as the alcohol that we drink, but don’t expect to get much performance from your six pack of bud light. Ethanol is a different type of alcohol with a much higher level of purity.
Environmental Impact of Biomass Energy
The carbon dioxide emissions from biomass can be offset whenever new plants are grown. Through photosynthesis, plants absorb roughly the same amount of CO2 as is given off through the burning of them. This results in a healthy and natural balance in CO2 levels in which net carbon emissions remain stable.
Technically, fossil fuels are derived from ancient organic biomass material, but they do not play a role in the carbon cycle. When fossil fuels are burned, nothing new is planted to make up for the carbon output. It’s because of this that they contribute to air pollution and global warming.
Biomass power plants produce much less harmful emissions than fossil fueled power plants. For example, coal gives off sulfur (the prime cause of acid rain and smog) and mercury (a harmful neurotoxin). They also produce much less NOx emissions (nitrogen oxide) which also contributes to poor air quality.
It’s important that energy crops are replanted and grown at the same rate as they are harvested for energy production. Not only is this important to preserve the balance of the carbon cycle, it also prevents crop and soil depletion for future sustainability.
Another concern is the displacement of trees, grasslands, forests, and savannas to make room for biomass crops. The destruction of these lands can lead to a chain reaction which impacts food production on many levels. Beneficial biomass resources will provide the needed crops for energy production without negatively impacting the environment or food sources. A delicate balance must be reached through careful analysis before any major biomass energy operation breaks ground.