Resolving the Biofuels Dilemma
It is prudent action to focus on feedstocks such as agricultural wastes
and residues. Here, a Verenium employee handles sugar cane bagasse
biomass (residue left after product extraction) to be used at the company’s cellulosic ethanol demonstration-scale plant in Jennings, La.
Commissioned in May, the facility is the first of its kind in the nation.
step to producing climate-positive biofuels. Feedstock yields, however, are only one component of a more fundamental measure, the total
energy yield per unit area. Doubling the amount of usable energy produced
from one bushel of corn will have the same effect as doubling the amount
of bushels produced per acre. In fact, it may have an even larger effect
when emissions from feedstock production, processing and transportation are taken into account.
An important aspect of the climate impacts of biofuels not
addressed in the Science papers is the carbon-storing ability of feed-stock-producing lands. Scientists have assumed that growing and
harvesting biomass feedstocks either reduces or at best has no effect
on carbon storage in the landscape. In many natural systems, however, increased use of biomass has the potential to result in more carbon storage. For instance, removing biomass from overstocked stands
in many forest types can reduce greenhouse gas emissions associated with catastrophic fires. Reclaiming degraded or desertified lands
with grasses or trees can greatly increase carbon storage in soils. The
positive climate impacts of these activities must be taken into account
when attempting to quantify the total impacts of a certain biofuel.
Pursuing a Climate-Positive Portfolio
Clearly the climate impacts of a particular biofuel are contingent
on a number of factors. Depending on management practices and site
characteristics, biofuels have the inherent potential to greatly outperform petroleum fuels or to rival them as greenhouse gas emitters. We
can maximize the positive climate impacts of biofuels by focusing on wastes
and residues, treading lightly on agricultural commodity markets, increasing yields and productivity, and aiming to use feedstocks that increase the
carbon storage of the lands on which they are grown.
Given this discussion, it is deeply troubling that the newly enacted renewable fuels standard precludes the use of biomass materials from
any federal forest lands — despite congressional, state and local priorities to reduce hazardous fuels to help prevent catastrophic wildfires.
The use of such material can help address multiple goals for more sus-
We should use the onslaught
of concern to help ensure we get it
right as we seek to implement
sustainable pathways. But we
should be careful not to throw the
baby out with the bathwater.
tainable forest management — and can provide feedstocks drawn from
waste/residues that do not affect land-use change or draw from agricultural commodity production. This disconnect in the renewable fuels
standard needs to be corrected.
It also is important to note that renewable biomass can be used
effectively in a number of energy applications beyond liquid transportation fuels. Woody biomass can be combusted at high efficiency
(up to 90 percent) to produce renewable thermal energy, electric
power or combined heat and power applications. Cofiring experiments
with both wood and switchgrass have demonstrated potential to
reduce fossil fuel use and improve emissions in traditional coal-fired
power plants. Anaerobic digestion, a process in which microorganisms
break down biodegradable material in the absence of oxygen, has been
used to produce both electric power and thermal energy from livestock
manure and other biomass.
The United States is blessed with an abundance of biomass to serve
these applications — but it is critical to know what kinds of biomass are
available where, in what quantities on a sustainable basis and at what
price. That is why a more comprehensive national biomass assessment
is needed and why we should conduct biomass assessments at the
state/regional level to ascertain the true variety of feedstocks available.
These assessments need to consider the amount and kinds of wastes,
including everything from food processing to prunings to manure to
wastewater treatment facilities. Wastes must become resources.
We should use the onslaught of concern about biofuels to help
ensure we get it right as we seek to implement sustainable pathways.
But we should be careful not to throw the baby out with the bathwater, as some vested interests would like. Biofuels, and biomass more generally, are an important piece of the solution. That said, perhaps the most
important thing we can do is to recognize that our societies will be better off the more energy efficient we are and develop a portfolio of
solutions to reduce demand. Improving the efficiency of our vehicles,
using biofuels with plug-in vehicles and greening the grid with distributed renewable energy can make the whole picture more manageable
and more sustainable. Reducing travel demand through better community design and better mass transit options will also help. Let’s not forget that the land-use change represented by converting countless acres
of agricultural land to sprawl every year also represents huge carbon
releases. Who is accounting for that?
Carol Werner ( email@example.com) serves as executive director of the
Washington, D.C.-based Environmental and Energy Study Institute, a nonprofit public policy organization dedicated to sustainable development.
Werner has more than 20 years of public policy experience on energy and
environmental issues and has organized dozens of congressional briefings.
She is a member of the American Solar Energy Society Policy Committee.