Biomass: A Sustainable Energy Source for the Future?
From creating sustainable jet fuel to developing consumer goods such as tissue and hygiene products, NC State’s College of Natural Resources is at the forefront of exploring the opportunities and challenges associated with the use of renewable biomass — plants that take in sunlight and carbon dioxide and make solid materials.
Biomass can be a complicated subject matter to those unfamiliar with forest biomaterials. “It’s anything that results from photosynthesis,” said Stephen Kelley, the Reuben B. Robertson professor in the Department of Forest Biomaterials. “In the college, it’s primarily wood, although we do some research with crops. It could also be algae or several different products.”
Biomass energy comes from various feedstock sources: trees and other plants like perennial grasses, waste and landfill gases. Forest residues like wood pellets can also be used to generate energy and heat, and potentially even liquid fuels.
Biomass has many benefits, the primary one being that it cannot be depleted like fossil fuels. With an abundance of plants on Earth, biomass could be a primary source of renewable energy that’s used as a sustainable alternative to fossil fuels.
Whereas sustainably managed biomass is considered carbon-neutral, the burning of fossil fuels releases carbon dioxide and other greenhouse gases, trapping heat in the atmosphere. This fuel source has been responsible for dangerous impacts on the environment, from air and water pollution to global warming.
According to Kelley, the pulp and paper industry will still be thriving 20 to 30 years from now, with more efficient uses and more considerable potential to make energy products and a wide variety of sustainable materials from woody biomass.
Educating students on the bioeconomy
The bioeconomy is one booming area for biomass, which is considered the largest renewable energy sector globally.
“A core component to biomass and its benefits is how it plays a role in the bioeconomy,” said Richard Venditti, Elis Signe Olson professor and associate dean of research in the College of Natural Resources. “The bioeconomy is a circular economy that is based on using renewable biomass to meet the needs of society. It produces products that are environmentally-compatible, where they can be reintroduced naturally into the environment after their use.”
At NC State, the Sustainable Bioproducts and Bioenergy Program serves to provide the knowledge and skills students need to advance the bioeconomy. The program is a collaborative effort between the Department of Forest Biomaterials and the Department of STEM Education and contains four courses, one of which Venditti co-teaches called “The Sustainable Bioeconomy.” The course focuses on how sustainable biomass can be harvested and the types of products that can be made from it, in addition to social, economic and environmental sustainability of these bioproducts. All course materials are available online for free and self-paced learning.
Because the bioeconomy is driven by sustainable products, they can be designed to be reintroduced into the environment without any harmful effects to surrounding ecosystems. The bioeconomy also provides benefits for rural areas in the United States, stimulating jobs and economies outside of factories and refineries located in cities.
“We’re promoting a rural economy and rural sustainability and all the benefits that come with growing plants,” Venditti said. “The encouragement of the growth of these more natural areas has a lot of eco-services. Plants help with the soil, provide recreational area, filter water, filter air, and provide wildlife places to live. The encouragement of the growth of these more natural areas has a lot of ecoservices.”
However, there are challenges to building a sustainable bioeconomy. One of those challenges is garnering the attention of younger individuals to create a more diverse workforce. According to Venditti, many younger individuals prefer to live in apartments in cities versus working and living in rural communities.
Another challenge comes with competition. Petroleum is an inexpensive resource with an industry that uses efficient technology to process it and make fuels and materials. Lastly, the inconsistency of using living material can be very challenging to the supply chain. Biomass is living material that is affected by variables such as the weather, insects, fungus and disease, making it less consistent than a barrel of crude oil coming from the ground.
“It’s not a given that everything from biomass is going to be better than synthetic sources. With any product, there’s always going to be plusses and minuses, but in most cases, biomass is favorable over synthetics,” Venditti said.
Harnessing woody biomass sustainably
The southeastern U.S. is heavily forested, making it a crucial source of biomass in the region. There are over 40 million acres of pine plantations located across the region, a vast majority of which is owned by private landowners who harvest trees. These pine plantations make up a tiny portion of total forest land in the southeast, but are the main source of biomass used by the wood products and pulp and paper industries.
While there are many opportunities for industrial forestry, harnessing woody biomass poses potential negative impacts on wildlife. A primary concern of environmental groups is that a market for woody biomass, especially wood pellets shipped to Europe, may increase the amount of timber harvested in some regions of North Carolina, causing negative impacts on surrounding wildlife. The industry that harvests wood pellets is establishing sustainability standards, such as not harvesting material from environmentally sensitive areas.
“There are a couple of ways that harvesting wood for bioenergy could affect biodiversity, including wildlife,” said Christopher Moorman, a professor and interim associate head of the Department of Forestry and Environmental Resources. “One is to reduce the amount of downed wood after a timber harvest because if there’s a broader market for the woody material, especially the smaller diameter, less desirable material, then there could be less left after the harvest. In that case, the site could potentially be more sterile and there could be less food and cover for wildlife linked to downed wood.”
Moorman and his collaborators conducted experimental research in the Coastal Plain of the southeastern U.S., which showed that most vertebrate animals — those with a backbone — appear not to be affected by reductions in the debris left after a biomass harvest. However, invertebrates, such as insects, show a mixed response, with some species favoring areas where no woody biomass was removed and others showing no response regardless of whether there was a harvest. Moorman recently completed a study in the southern Applachians that showed mice favored timber harvests that left more downed wood on site, which indicates that increased removal of woody biomass in the region may negatively affect mice and other wildlife.
One approach to ensure the sustainable harvest of woody biomass is to leave a portion of the woody biomass suitable for bioenergy behind after a harvest, which maintains habitat for wildlife such as mice and insects. Moorman recommended that retained debris be redistributed across the harvest site, which will spread the food and cover resources out for a wide array of nearby wildlife.
“As harvest technologies evolve and possibly become more efficient, it is important to monitor residual woody debris and associated wildlife and make sure relationships are on par with what we saw in our studies,” Moorman said.