During the 1920s, German scientists discovered a way to synthesize oil from long-chain hydrocarbons. These include biomass, coal, or other carbon-based material, which was then made into fuel that worked in existing internal combustion and diesel engines. Called the Fischer-Tropsch method after its discoverers Franz Fischer and Hans Tropsch, Germany used this process to produce synthetic fuels during World War II, as the country had no domestic petroleum resources. South African company SASOL still uses this method to convert some of the country’s vast coal reserves into liquid fuel. This same process can also be used for wood biofuel production.
Biofuels from Waste
Biofuel can be made from any waste materials derived from plants, algae, or even animals. This is referred to as biomass and, since these materials are easy to replenish, the biofuel produced from them is a form of renewable energy. It essentially mimics the process in which crude oil formed underground over millions of years, emitting the same amounts of carbon when it’s burned that the materials initially absorbed. However, unlike fossil fuels like natural gas, coal, or petroleum, biomass is easy to produce and, even better, it’s more sustainable.
While environmental concerns are associated with the amount of arable land biofuel used to ensure sufficient feedstock is available for production, advocates tout it as a cost-effective and generally benign alternative to existing fossil fuels. As petroleum and other carbon-based fuels have been scientifically linked to climate change, biofuel offers great promise as a carbon-neutral replacement. Using unwanted wood from lumber mills and other businesses that produce large amounts of wastage also creates new markets for materials previously considered unusable.
A Norwegian utility company called Statkraft uses wood chippings and other organic waste to produce biodiesel. Through the use of wood and other organic waste, the company also avoids criticism about using valuable farmland for creating biomass. Statkraft intends to expand the types of green fuels it makes to include aviation fuel and biofuels for other purposes.
“This could be revolutionary,” stated Statkraft CEO Christian Rynning-Toennesen at a utilities industry conference. “It could have the same widespread impact as wind turbines or solar photovoltaics. Mankind needs liquid fuels, just not fossil liquid fuels.”
How Wood Biofuel Production Works
Companies in the United States are also embarking on ways to produce fuel from woody biomass. Using the Fischer-Tropsch process, Colorado company Red Rock is planning a $320 million facility that will take in biomass from wood and convert these liquid hydrocarbons into diesel, naphtha, and jet fuels. Set to open in the spring of 2021, the site looks to use woody biomass sourced from byproducts gathered from forest thinning projects meant to reduce the chance of wildfires in the area.
The Fischer-Tropsch process for converting wood biomass into liquid fuel requires three steps:
- Convert wood biomass into what’s known as synthesis gas (syngas), which is a mixture of carbon monoxide and hydrogen.
- This feed material is used to produce a mixture called synthetic crude oil (syncrude), resulting from catalytic polymerization and carbon monoxide hydrogenation. Syncrude contains hydrocarbons, oxygenates, and water.
- Syncrude is then refined in the same way as conventional crude oil to create various petrochemicals and fuels used in the transportation industry.
The process in which Red Rock will produce biofuel involves grinding down the material into slivers half the size of toothpicks. These wood slivers are then heated in a high-pressure and oxygen-free environment to 1,800˚ F (982.2˚ C). This converts the material into a gas, which is then liquified and processed into biofuel.
In fact, the US military has considered this model as a way to reduce its carbon emissions. Using waste biomass from wood provides a cost-effective alternative to petroleum-based fuel as well, offering a price under $3.50 per gallon on average. This method can even be used to manufacture renewable diesel and sustainable aviation fuel (SAF).
Machinery Used in Wood Biofuel Production
A key element in wood biofuel production involves grinding down the material into fine particles with consistent shapes and sizes. Since size reduction is so important in the process, horizontal hammermills are commonly used in processing biofuel from wood waste. Hammermills are particularly effective at particle reduction and help control problems related to water content within the biomass.
Besides hammermills, other machinery is used in the processing of biomass:
- Pellet mills are used mainly for large-scale commercial operations, as their features include higher output, lower consumption and longer working lifecycles. They work by pressing the biomass mash into uniform pellets.
- Counterflow coolers offer the best cost to performance ratio. Using rotary distributors, they cool the wooden biomass pellets gradually and evenly from the bottom to the top in bin rooms.
- Vibrating sifters are compact machines that work efficiently to clean the pellets made from the biomass, removing grit and fine particles from them.
- Rotary screeners catch biomass material that falls onto the center of the screen before putting it through a centrifuge to remove particulates. The screener separates the coarser material from the finer material within the biomass.
Other types of machinery can also be modified and customized to fit a manufacturer’s purposes.
Prater Wood Processing Equipment
Prater Industries makes a variety of machinery that can be used in wood biofuel production. Its reducing machinery includes hammermills, rotary screeners, vibrating sifters, and other machinery that can be easily customized for producing biofuel from wood waste. Additionally, Prater has considerable experience in putting together customized particle reduction systems that can be utilized to produce biofuel from wood waste.
