Cherney, Jerry (Cornell University, Dept. of Crop and Soil Sciences, 503 Bradfield Hall, Ithaca, NY, 14853; Phone: 607-255-0945; Fax: 607-255-2644; Email: jhc5@cornell.edu)
J.H. Cherney *, P.B. Woodbury, S.D. DeGloria
Use
of herbaceous biomass for energy production can significantly reduce greenhouse
gas emissions in the northeastern USA. Our objective was to evaluate the
potential for grass production in New York State and to develop agronomic
management strategies to improve the energy characteristics of this feedstock.
The northeastern USA has a considerable acreage of unused or underutilized
agricultural land. The estimated potential underutilized crop area in New York
State is approximately 1.5 million acres, based on data from satellite imagery
and the census of agriculture. Some of this land is reverting back to woody
growth while some of it is in government programs. Much of this land has
encountered difficulties growing row crops and is in some type of grassland.
Almost all of this land could grow grass crops for bioenergy, regardless of how
marginal the soils are for agricultural production. Potential yield estimates
of 1.25 ton/acre unimproved grassland, and 2.5 ton/acre for managed switchgrass
(Panicum virgatum L.) and reed canarygrass (Phalaris arundinacea L.) were
selected as economic cutoff values for production of these crops. Based on
these economic cutoffs reed canarygrass could be established on 96% of
currently unused acreage, while switchgrass could be economically established
on 80% of this acreage. Without any fertilization or other inputs approximately
81% of this unused land could be economically harvested once a year for
biomass. Based on soil-specific predicted crop yields approximately 6 million
tons of reed canarygrass could be produced on these lands in New York State.
Ash content of grasses has a major impact on combustion value of the feedstock.
Six fields of mixed cool-season grasses with some legumes and weeds were cut in
August 2004 and harvested two to three weeks after cutting using commercial hay
equipment to evaluate ash reduction strategies. Primary species were timothy
(Phleum pratense L.), tall fescue (Festuca arundinacea Schreb.), alfalfa
(Medicago sativa L.), tall oatgrass (Arrhenatherum elatius L.), goldenrod
(Solidago canadensis L.) and bedstraw (Galium aparine L.). The range in ash
content of these primarily grass mixtures was 3.9-5.2%. Energy value of grass
ranged from 19.6-21.2 MJ/kg, compared to 21.7 MJ/kg for premium wood pellets.
All grass samples contained 0.01% sodium, while potassium content ranged from
0.43-0.82%. Sulfur ranged from 0.09-0.12% and chloride ranged from 0.01 to
0.04%. This compares to premium wood pellets with ash = 1%, sodium = 0.02%,
potassium = 0.10%, and no detectable sulfur or chloride. Grass pellets are
currently being tested in pellet stoves, pellet boilers and gasifiers in Europe
and North America. Grass biofuel pellets emit up to 90% less greenhouse gasses
than conventional energy sources such as oil, coal and natural gas. If
approximately 5.5% of all residential buildings in New York State were heated
with pelleted grass or wood, this could offset 100% of all greenhouse gas
emissions attributed to agriculture in New York State. Perennial grass is ideal
for animal manure nutrient management, soil conservation, maintaining open
spaces, and compatible with wildlife nesting opportunities. A simple one cut
per season perennial grass biomass program has maximum sustainability for an
agricultural cropping system. Grass pellet biofuel is a very promising
sustainable, economically-viable, and environmentally-friendly alternative
energy source. It has great potential for near-term implementation and positive
impact on greenhouse gas emissions.