Energy Sustainablity in NC: Forest Biofuels

The following is a blog entry written by Steven Pires, a Sierra Club member and Grad student at NCSU's Department of Forest Biomaterials Science and Engineering. This is the first post in a new series that will focus on how North Carolina can lead the way in alternative energy production.

The practice of sustainability and sustainable development becomes critically important as global populations and natural resource demands continue to rise. According to the US Census Bureau, the global population is expected to exceed 9 billion by 2050. This staggering figure leaves us with no choice but to be more environmentally conscious with the use of our resources. Steadily rising natural resource demand coupled with increasing public environmental concerns has sparked major investments in the renewable energy sector.

Biofuels are attracting a considerable amount of attention due to their unique ability to provide a direct substitute for conventional gasoline and their (arguably) carbon neutral renewable character. But, this attention has also brought scrutiny upon the biofuel industry, questioning their true environmental benefits. Until recently, the United States has focused their attention on corn-based ethanol (also known as, first generation biofuels). Contention surrounding first generation biofuels are justified through a number of logical avenues. First, corn is one of the, if not the most, energy intensive crops requiring both labor intensive site preparation and huge amounts of petroleum derived fertilizer. Secondly, corn has a more compelling value as a food source than a fuel source. There have been numerous Life-Cycle Assessment studies which come to a variety of conclusions about the environmental performance of these renewable fuels. First generation biofuels tend to have marginally better to significantly worse environmental performances than current petroleum transportation fuels. On the other hand, second generation biofuels prove to have positive environmental performances when compared to petroleum fuels.

Keeping that in mind, it is exciting to consider the technological advancements made in, what we are now considering, second generation biofuels. Second generation biofuels are renewable fuels derived from non-food source cellulosic biomass (example: trees, wood residue, crop residue, landfill waste, grasses, etc). Expanding the second generation biofuel industry in the Southeastern United States has the ability to enhance economic development, promote energy security, and reduce the environmental impact of our fuel consumption. The Renewable Fuels Standard set out in the 2007 Energy Bill calls on the US to produce 36 billion gallons of biofuels by the year 2022 in hopes of promoting more green jobs and augmenting the amount of money spent on foreign fuels. The Renewable Fuels Standard seeks to cap our production of corn-based ethanol at 15 billion gallons a year while requiring the rest of the 36 billion gallons to be represented by second generation biofuels. This provokes the question of how we will successfully meet this goal from both a technological and economic perspective while still reducing green house gas emissions.

Major declines in the paper industry are causing existing facilities across the Southeast to halt operations, slowing economic activity and biomass utilization. These facilities have the capability and capacity to process this biomass (mostly hardwood and softwood) to a finished biofuel product with little modifications to the existing facilities. The process of taking an old paper mill and converting it to a biofuel refinery is known as “mill repurposing” and is gaining attractiveness on the economic development side of the equation. NC State and the Department of Forest Biomaterials are currently leading research and development in mill repurposing technology.

Using woody biomass to create biofuel also has its regulatory and political hurdles to overcome. Both first generation and second generation biofuels are currently being scrutinized due to a consideration many researchers feel is being left out of the equation: indirect land use change (ILUC). ILUC considers the total life cycle effects of the carbon emitted due to land use change from converting natural landscapes to croplands for biofuels. I project this is going to be a huge point of contention for the biofuel industry, policy makers, and the public to reach an agreement. A policy guiding the responsible use and management of these new biofuel croplands is critical for the success of the industry. This policy should also be geared towards giving environmental activist groups peace-of-mind that the proper steps are being taken to come up with a best management practice. Utilization of woody biomass does offer some advantages to this ILUC debate. Although plantation forestry will most likely be a monoculture crop, these trees sequester huge amounts of carbon and have long harvest rotation times (8-10 year rotations) compared to switch grass (harvested 1-2 times per year).

There is much room to debate and improve on the current status of biofuels. That being said, I’m sure we all can agree that the investments and increasing attention on this particular renewable energy source will have a positive domino effect. This is not the end all solution to our problems, but it is a step in the right direction towards creating an all encompassing renewable energy infrastructure within the United States.

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The whole time I'm reading this

my mind kept saying "hemp" I really thought he might get there when he talked about "long rotation times" How does switch grass compare with hemp as a biofuel? (beside the fact that it's not legal to grow it)

Progressives are the true conservatives.

Steven says

"This is a good point to make. Both crops (switchgrass and hemp) can be grown on marginal soils with little inputs of fertilizer and pesticides. The chemical composition of the plants are quite similar, both having high (~30-35%) cellulose concentrations with slightly a higher total cellulose content in hemp. Cellulose is the key building block of all plant materials, and the focus of "second generation biofuel" production. Cellulose can isolated from other plant building blocks, then be fermented (biologically) to produce our final product (i.e., ethanol).

Hemp fibers are considerably longer than switchgrass fibers which opens some opportunities for co-product generation. Total biomass yield per acre of land seems relatively equivalent. Depending on geographic location and fertilizer input, one crop could generate more biomass over another.

The two biggest reasons for switchgrass use over hemp that I see are the following:

1) Hemp is a controlled substance in the US
2) Switchgrass occurs naturally across the grasslands of the United States and is a key component to grassland ecology (providing habitat for many species of birds, small mammals, etc); wheras, hemp is not a natural occurring plant species in the US and would most likely be considered an invasive species."

NC Sierra Club