Biomass resources run the
gamut from corn kernels to
corn stalks, from soybean and
H   Bcanola oils to animal fats, from
prairie grasses to hardwoods,
Are Produced          and even include algae.
In the long run, we will need
diverse technologies to make use
of these different energy sourc-
es. Some technologies are already developed; others will be.
Today, the most common technologies involve biochemical,
chemical, and thermochemical conversion processes.
Ethanol, today's largest volume biofuel, is produced through
a biochemical conversion process. In this process, yeasts
ferment sugar from starch and sugar crops into ethanol. Most
of today's ethanol is produced from cornstarch or sugarcane.
But biochemical conversion techniques can also make use of
more abundant "cellulosic" biomass sources such as grasses,
trees, and agricultural residues.

NREL's researchers develop processes that use heat,
pressure, chemicals, and enzymes to unlock the
sugars in cellulosic biomass. The sugars
are then fermented to ethanol, typically
by using genetically engineered micro-
organisms. Because cellulosic ethanol
is the leading candidate for replacing a
large portion of U.S. petroleum use, it is
the focus of DOE's Biomass Program.

A much simpler chemical process is
used to produce biodiesel. Today's
biodiesel facilities start with vegetable
oils, seed oils, or animal fats and react
them with methanol or ethanol in the
presence of a catalyst. In addition,
NREL's genetic engineering work has
produced algae with a high lipid content
that can be used as another source
of biodiesel.
Algae are a form of biomass which
could substantially increase our nation's
ability to produce domestic biofuels.
Algae and plants can serve as a natu-
ral source of oil, which conventional
petroleum refineries can convert into jet
fuel or diesel fuel-a product known as
"green diesel."

NREL researchers also explore and develop thermochemical
processes for converting biomass to liquid fuels. One such
process is pyrolysis, which decomposes biomass by heating it
in the absence of air. This produces an oil-like liquid that can
be burned like fuel oil or refined into chemicals and fuels,
such as "green gasoline." Thermochemical processes can also
be used to pretreat biomass for conversion to biofuels.
Another thermochemical process employed at NREL is gas-
ification. In this process, heat and a limited amount of oxygen
are used to convert biomass into a hot synthesis gas. This
"syngas" can be combusted and used to produce electricity in
a gas turbine or converted to hydrocarbons, alcohols, ethers,
or chemical products. In this process, biomass gasifiers can
work side by side with fossil fuel gasifiers for greater flex-
ibility and lower net greenhouse gas emissions.
In the future, biomass-derived components such as carbohy-
drates, lignins, and triglycerides might also be converted to
hydrocarbon fuels. Such fuels can be used in heavy-duty ve-
hicles, jet engines, and other applications that need fuels with
higher energy densities than those of ethanol or biodiesel.

Energy Required to Produce Fuels
Total Btu Spent for 1 Btu Available at Fuel Pump

3

2.5
2
-
1.5
a,
d
a,
m

0.5
0

From Biomass
From Coal & Natural Gas
From Petroleum
Fuel-to-Petroleum
Ratio = 0.9
81% Efficiency

Gasoline

Fuel-to-Petroleum
Ratio =10
57% Efficiency

Corn Ethanol

Fuel-to-Petroleum
Ratio =10
45% Efficiency

Cellulosic Ethanol

Based on "Well to Wheels Analysis of Advanced Fuel/Vehicle Systems"by Wang et al. (2005)

E~vIhm

Energy
in the
Fuel

*
~

I                                             _