Grass Biofuel Pellets: Assessing the potential to respond to North
America's energy concerns
March 23, 2001
by R.Samson, R. Jannascha and T. Adams
Introduction
Unprecedented opportunities for biofuel development are occurring as
a result of a combination of factors including: rising oil, natural
gas and electricity costs, energy security concerns in the US, and
the need to reduce greenhouse gas emissions. The 1.1 billion acres of
farmland in North America could help mitigate these concerns if
currently viable biofuel production systems were expanded.
In most agricultural regions, warm season grasses such as switchgrass
can be successfully grown at a cost of USD $2-$3/GJ. Much of this
farmland can collect 100-250 GJ of energy per hectare with existing
production technology and plant materials. Efforts have been made to
produce power and liquid fuels from this material, but the
development strategies demonstrated so far appear to be sustainable
only with subsidies. Converting this feedstock into a viable energy
option suitable for widespread application requires an energetically
efficient, economical, and convenient energy transformation pathway
to meet consumer energy needs.
Finding Energy Farming's Comparative Advantage
The recent development of a "close coupled" gasifier pellet stove
capable of burning moderately high ash pelleted agricultural fuels
provides a completely new fuel cycle for energy farming development
[1]. When burned in the gasifier stove, pelleted switchgrass provides
fuel conversion efficiencies and particulate emissions in the same
range as modern oil furnaces. Each GJ of grass pellet energy
delivered to consumers thus directly substitutes for one GJ of
delivered oil and can be utilized on a large scale without
significant air pollution. The pelletized grass biofuel systems
builds on, and is likely to overtake, the existing wood pellet
heating industry, which is rapidly developing without any significant
level of government intervention.
Pelletized grass biofuel is poised to become a major fuel source
because this fuel pathway is capable of meeting some heating
requirements at less cost than all available alternatives. The
cost-effectiveness of pelletized grass as a fuel results from:
* efficient use of low cost marginal farmland for solar energy collection
* minimal fossil fuel input use in field production and energy conversion
* minimal biomass quality upgrading which limits energy loss from the feedstock
* efficient combustion in advanced yet modestly priced and simple to
use devices
* replacement of expensive high-grade energy forms in space and water heating
Contrary to the prevailing wisdom that reducing greenhouse gas
emissions will raise societal energy costs, pelletized biofuels can
provide consumers with lower and more stable heating costs while
dramatically cutting greenhouse gas emissions. Given that
agricultural commodity prices are declining in real dollars, pellet
fuels are likely to become cheaper over time. By contrast, wood-based
pellets have been rising in cost due to ongoing improvement in
industrial wood utilization which is reducing the waste fraction of
delivered roundwood. Furthermore, the development of a grass pellet
biofuel industry has great potential to revitalize the rural economy
of North America by absorbing the surplus production capacity of the
agricultural sector and cutting on-farm fuel costs in heating
intensive sectors like green houses.
The Potential for Energy Farming with Grasses
Of the farmland in North America (932 million acres in the US and 168
million acres in Canada), we estimate that 150 million acres could be
dedicated to energy farming without appreciably affecting North
America's food production capacity. Assuming biomass energy crop
yields are 50% higher than the current harvested hay yields,
harvested perennial grass yields of 5.9 and 8.1 tonnes/ha in Canada
and the US respectively can be expected.
By energy farming 130 million acres in the US and 23.4 million acres
in Canada, a total production capacity of 424 and 55 million tonnes
could be achieved in the two respective countries. Assuming grass
fuel pellets contain 18.5 GJ of energy/tonne, 8.9 billion GJ (an
energy equivalent of 1.5 billion barrels of oil) could be produced
each year from energy crop production on 14% of North American
farmland. With U.S. crude oil imports of approximately 3.4 billion
barrels per year, the U.S. could displace the equivalent of 39% of
its oil imports by growing biofuels on 14% of its farmland.
The Economics of Pelleted Biofuels
The most promising regions to develop a grass pellet fuel industry
are those where hay production costs are low (generally indicated by
low land rent) and heating costs are high due to a long winter
heating period and high fossil fuel costs. Based on hay prices, land
costs and switchgrass performance data in North America, and the
relative winter heat c
