|
Archives
Blacktop or Biomass?
When I was a kid, we moved to the “burbs”. Actually, the “burbs”were
new subdivisions on the southwest side of Chicago, surrounded by mud and cornfields.
We lived in the middle of nowhere
as far as I was concerned.
As I grew, I watched the “middle of nowhere” grow
with me. Cornfields were replaced with newer, bigger houses and lots of retail
stores with even bigger parking lots. Eventually we bought a summer home, on
a river in the middle of nowhere, surrounded by cornfields. And over the years
I watched houses and stores and parking lots expanding there as well. I also
noticed that for every field where corn was actually growing, there were an
equal number of fields that were left empty.
Pick up a newspaper today, or watch a newscast on TV, and we hear of global
warming, greenhouse gases, energy conservation, ethanol, etc. President Bush,
in his State
of the Union address urged Congress to pursue the goal of “Twenty In Ten” – a
reduction of gasoline usage by 20 percent in the next ten years. To accomplish
this, America must learn to become less dependent on oil, and more dependent
on alternative fuels. So, if we become less dependent on domestic and foreign
oil, then where does the source of our alternative energy come from? In a word,
biomass.
Biomass defined in broad terms is “all plant and animal waste on the Earth’s
surface.” More directly, biomass is all energy captured by photosynthesis,
and as such, emits no net greenhouse gases. Already, biomass has outdistanced
hydropower as the largest source of renewable energy. In 2003, biomass supplied
approximately 2.9 quadrillion Btu (quad) of energy. Currently, biomass supplies
close to 3% of the total energy consumption of the United States.
A Biomass Program was set forth by the U.S. Department of Energy, Office
of Energy Efficiency and Renewable Energy with the enviable goal that biomass
will supply
enough power, fuels, and chemicals by 2030 to equate to 30% of the current
petroleum consumption in the U.S. But this will not be an easy, or cheap, goal.
 Biomass comes in many forms: urban, woody, agriculture, forestry, animal, and even municipal waste can be used.
Many benefits can be gained from the development of biomass technology. Environmentally,
biomass is nontoxic and biodegradable. Biomass essentially reduces greenhouse
gas by completing the carbon cycle: plants take CO2 from the air during the
growing process and release CO2 back into the air during the burning process.
Thus, CO2
is balanced out and the process is considered “carbon neutral”. Economically,
biomass creates new job markets for farmers and foresters, finds new uses for
land not currently being used, and reduces the trade deficit. Biomass use will
ultimately reduce our reliance on foreign oil, improving the nation’s
energy security; and best of all, it is produced domestically, not imported.
With increased technology comes increased concern: Will there be enough agriculture
grown to feed the population and meet our energy and materials needs? According
to Dr. Robert Armstrong of the National Defense University “our natural
resource base of land and water is more than adequate to meet the demand.”
The United States land base consists of nearly 2,263 million acres of forest
land, grassland pasture, cropland, special use land, and miscellaneous use
land. At least
half of this land has the potential for growing some sort of feedstock crop.
For the past 10 years an average of 50 to 55 million acres of agricultural
land has been retired annually according to the Oak Ridge National Laboratory
records.
Conservation measures and economic gains have literally put the farmer out
of work.
Now, ORNL is working to put the farmer back in business. It is estimated
that 1 billion dry tons of biomass feedstock annually will be necessary to
meet
the 2030 goals. Scientists and researchers at the Departments of Energy and
Agriculture
have determined that forest resources can produce 368 million dry tons of biomass
annually. Add to that the nearly 1 billion dry tons of biomass produced from
agricultural and animal resources, and it is clear that the United States has
the potential to meet its goal. In addition, research is being conducted to
determine the feasibility of replacing some crops with fast-growing grasses,
switchgrass,
and trees such as poplars and willows. When that happens, we will have accomplished
not only steps towards oil independence, but we will have put idle land to
use. There is no question that we are more than capable of sustaining a bio-based
economy.
So we have the crops, we have put the land to use. What happens next?
The feasibility of a bio-based economy is contingent upon getting materials
from the source to its destination – in this case, to the biorefinery – in
the most economical way. This is not an equipment issue, rather a limiting
of the accessibility to the biomass. Moving material to biorefineries requires
roads.
In many areas, access to roads is unavailable and/or environmentally restricted.
Cost of transportation must be accounted for when determining the economic
feasibility of utilizing biomass.
 Once the biomass has been harvested, it is transported to a biorefinery where it undergoes conversion to a usable form.
Biomass is transported to a facility known as a biorefinery. Much the same
as oil refineries, the biorefinery works to achieve the highest possible value
out
of biomass feedstocks. While producing chemical products from feedstocks, a
biorefinery might also produce liquid transportation fuels as well as generate
electricity
for their own use. It is hoped that some day this will lead to the production
of enough electricity to sell into the grid. Some technologies have already
been developed. Others are on the drawing table.
 Switchgrass can yield almost twice as much ethanol as corn, estimates geneticist Ken Vogel, who is conducting breeding and genetics research on switchgrass to improve its biomass yield and its ability to recycle carbon as a renewable energy crop. Photo by Brett Hampton.
Currently, biorefineries work on two platforms based on the end product desired.
The “sugar platform” is based on a biochemical conversion within
the refinery. The “syngas platform” is based on a thermochemical
conversion process. Referred to as platforms, these two processes could potentially
make a wide range of fuels, chemicals, power, and materials.
Biomass is converted into many forms of usable energy. At the forefront of
research is the introduction of liquid transportation fuels, or biofuels.
 Cellulosic biomass consists of three main components: Cellulose, Hemicellulose, and Lignan.
During the oil embargoes of the ‘70s, the Department of Energy began
exploring the use of biofuels. The most popular of these biofuels today is
ethanol. With
over 60 ethanol plants in operation or being constructed, the United States
is at an annual production level of 1.5 billion gallons. Most of this ethanol
comes
from the fermenting of corn kernels. Through the DOE program, it is hoped that
technology will be developed to produce biofuel not only through the sugar
of corn kernals, but with many more types of biomass.
Ethanol is produced through a biochemical, or sugar platform, process. The “sugar
platform” uses simple sugars to obtain results. Starting with the corn
kernel, it is broken down to its starch component where it is then fermented
into ethanol. More advanced studies are being conducted by NREL to include
the use of cellulose, and its counterpart, hemicellulose, the fibrous material
that
holds a plant together, thereby expanding the option for using more types of
feedstock. Sources of cellulosic biomass include stalks, husks, and leaves
from corn, tree limbs, wood chips, sawdust, and municipal solid waste.
Cellulosic biomass has traditionally been used as fuel, paper, and building
materials. Biorefineries are developing the technology to break down these
complex, unedible
components into fermentable sugars. The remaining product, lignan, is recovered
and used as an energy source.
In addition to ethanol, sugar from cellulose and hemicellulose can be used
to produce organic acids such as citric acid, levulinic acid and lactic acid,
and
chemicals such as xyliol and xanthum gum. It has been estimated that production
of these bio-based chemicals could potentially contribute as much as $80 billion
to the economy.
The “syngas platform” uses a thermochemical process to heat the
biomass with a minute oxygen supply to produce a synthesis gas, or a gaseous
mixture
of carbon monoxide and hydrogen. Known also as a gasification process, the
syngas burns cleaner and more efficiently and can be used to produce electricity
in
turbines or for a wide variety of other products.
 Biomass that is rich in carbohydrates, like corn and soybean, can be converted directly into biofuels to meet our transportation needs. The biofuel ethanol is mostly used as a fuel additive to reduce vehicles' smog-causing emissions. Photo courtesy of U.S. Department of Energy.
Another thermochemical process that converts biomass to a liquid fuel is
known as pyrolysis. Pyrolysis produces an oil-like liquid which can be burned
like
fuel oil or it can be used to pretreat biomass.
Other platforms are currently being researched and developed by NREL scientists.
Biogas is being developed from landfills and animal manure. A complex mixture
of methane, carbon dioxide, and other gases, biogas has the potential of being
used for power generation or compost material.
To be sure we have only scratched the surface of a “biomass” economy.
The potential to draw from such resources as aquatic biomass exist. Studies
have shown the idea works: use of biomass can reduce greenhouse gas emissions
considerably;
it puts people back to work; it reduces our dependence on a finite amount of
fossil fuel; a co-product of corn and soybean production is protein, which
can be used as a feed material for livestock; conversion of animal manure to
bioenergy
reduces groundwater contamination; perennial crops produce less soil erosion,
less soil disturbance and better habitats for birds and mammals; and, we have
the resources to do it.
On the other hand, we don’t have the technology available just yet
to convert all forms of biomass into usable, cost-effective products. There
are
long-term
concerns about removing such massive quantities of cropland, and attitudes
regarding utilization of perennial crops, harvesting and collection technologies,
and transportation
issues need to change.
Biomass and biorefineries will never eradicate the need for oil. But they
will play a key role in making our world a more sustainable one.
Seems to me that Mother Nature has given us the answer. Now we need to work
harder to make this century the renewable energy century.
Archives
|
