[Gasification] Biomass Gasification to Improve Ethanol Energy Balance

[Jane Turnbull]

This is from the Energy and Environmental Study Institute posting.

Jane Turnbull

Commentary     


Paving the Way for Cellulosic Ethanol, by Brendan Jordan of the Great Plains
Institute 

High natural gas prices have convinced the management of two corn ethanol
plants in Minnesota to replace their natural gas consumption with biomass.
For the uninitiated, biomass is any plant material, and generally refers to
plant material used for energy. Common biomass materials include wood waste,
crop residues, and dedicated energy crops like hybrid poplar and
switchgrass. Both the Chippewa Valley Ethanol Company (CVEC) and the Central
Minnesota Ethanol Cooperative (CMEC) are installing biomass gasifiers this
year that will use waste biomass to produce heat and electricity to replace
energy previously purchased on the market. In addition to improving their
bottom line and shielding them from energy price fluctuations, this will
also dramatically improve the CO2 emissions profile of their fuel, and set
the stage for producing cellulosic ethanol.

Faced with high natural gas prices, many ethanol plant operators are looking
for other sources of process heat. According to a recent study (Tilman et al
2006), 60 percent of the lifecycle energy used in producing ethanol is made
up of energy used in the plant for such processes as cooking the corn,
distilling the ethanol, and drying the distillers grain.  Most plants use
natural gas to supply that energy.

High natural gas prices are causing problems for ethanol plants all over the
Midwest. According to an article in Ethanol Producers Magazine from
September 2005, CMEC spent $250,000 per month on natural gas in 2002 -- by
2005 that cost had doubled to $500,000 per month.

Sebesta Blomberg, a technical and business solutions provider, is working
with the Central Minnesota plant to plan their gasification project. They
connected the plant with a technology provider, Primenergy of Tulsa, OK, and
helped connect the plant with a source of biomass. CMEC is located in
central Minnesota on the boundary between farm and forest country.  That
means that a wood supply was widely available. The cooperative has signed a
10-year contract with a supplier of wood waste.

Not only will the plant replace natural gas, but it will also produce
electricity.  The gasifier will power a combined heat and power system that
will sell 1 MW of green electricity to Xcel Energy.

In addition to saving money for the plant, the new equipment will
dramatically improve the environmental profile of the fuel. The typical
fossil energy ratio of a corn ethanol plant is around 1.7:1. CMEC, with its
new equipment, will have an energy ratio of 3.15:1. In other words, for
every unit of fossil energy used in production, they¹ll get 3.15 units of
ethanol. This translates into reduced fossil energy consumption, and a
greater reduction in greenhouse gas emissions.

Frontline Bioenergy is the lead in designing and building the gasifier for
Chippewa Valley. They plan to have Phase 1 of their project operating by
early 2007. By then they will have a 70 ton per day gasifier operating using
a combination of wood chips and corn stover. This will replace about 20
percent of the plant¹s natural gas. When Phases 2 and 3 are completed in
early 2009, they will replace over 90 percent of the plant¹s natural gas
using primarily corn stover. Frontline¹s gasifier is especially suited for
utilizing a variety of such feedstocks.  This project should have a similar
renewable energy ratio to the Central Minnesota project.

These projects have a variety of immediate benefits (fossil energy
reduction, cost savings), but they are really important because they¹re
positioning the ethanol business to move towards cellulosic ethanol. This is
true for two reasons: they¹re helping plants learn how to collect and handle
biomass, and they¹re helping plants learn how to use gasification
technology, which can be a precursor to production of liquid fuels such as
ethanol and synthetic gasoline and diesel from biomass.

The Department of Energy has calculated that up to 1.3 billion tons of
biomass could be produced for energy purposes in the United States without
significant impacts on the food supply. This is enough biomass to replace
more than one third of current petroleum consumption.  The problem is that
while this biomass is available, it isn¹t stacked up outside the plant
waiting to be used. There are logistical challenges in collecting and
storing that biomass. Most industrial plants are hesitant to participate in
such projects involving new technology and large scale biomass supply
logistics. These are risks that a plant isn¹t willing to take until it has a
proven technology. Thus, the chicken and egg problem with cellulosic ethanol
­ technology risk and feedstock risk combined make it difficult to
demonstrate cellulosic ethanol plants.

The CMEC and CVEC projects are getting around this problem in a clever way ­
by selecting a reliable feedstock for demonstrating the technology. Both
projects will be using waste wood for their first phase ­ a feedstock that
is a by-product of another operation (hence wood ³waste²). Then, once the
technology is demonstrated, they can tackle the feedstock challenge by
building a feedstock supply for a proven technology. Once a feedstock supply
is collected and available, it could be used for various gasification
technologies.

The advantage of gasification technology is that it can be a bridge to
various other energy technologies. Gasification can be combined with gas
clean-up and methanation to produce pipeline quality natural gas. It also
can be paired with various processes to produce a variety of liquid fuels,
including synthetic gasoline and diesel and, yes, ethanol.  Other
possibilities for products from gasification include purified hydrogen,
ammonia for fertilizers, and acetic acid and bioplastics.  Engineers with
both Frontline Bioenergy and Sebesta Blomberg feel that the plants they¹re
working with will produce liquid fuels from gasification in the near future.
Once the plant gasifies enough biomass to power the ethanol plant, it can
start exporting energy from the gasifier, either as natural gas or liquid
fuels. So, in answer to the commonly asked question of whether a corn
ethanol plant can transition to a cellulosic ethanol plant? The answer would
appear to be yes. And CMEC and CVEC are showing the way.

Sources:

Hill, J., E. Nelson, D. Tilman, S Polasky, and D Tiffany. Environmental,
economic, and energetic costs and benefits of biodiesel and ethanol
biofuels. Proceedings of the National Academy of Sciences. 2003
103:11206-11210.

Korba, Ron. ³Turning Off the Valve². Ethanol Producers Magazine. September
2005.