Biomass Feasibility Project Final Report - Xcel Energy

Since NASS doesn’t provide a similar data set for Minnesota’s swine herds, we use a different
method to estimate the technical energy potential of swine manure. Economic analyses of
anaerobic digesters running swine manure suggest they need a herd of at least 12,000 to
operate economically in Minnesota. Unfortunately, NASS provides a state inventory of only
swine herds greater than 5,000 head, encompassing 46% of Minnesota’s pigs (NASS, 2006). We
estimate technically available swine manure at 46% of county-level theoretical estimates, but
since many states don’t have such herds, the resulting figure probably overstates the state-wide
technical potential Lacking more precise information on the size and geographical distribution
of the state’s large swine operations, however, we can’t provide a more exact calculation.
Further screens. We next subject other biomass categories to a series of screens, beginning with
price. Feedstocks more expensive than natural gas are eliminated because they aren’t costeffective
for base-load generation. That eliminates most animal processing wastes, crops and
crop-processing residues.
The next screen rules out feedstocks used by industries to create high-value products. Most of
those feedstocks are ~ 3 times the price of coal and therefore uncompetitive for base-load
power generation. They probably would become even less competitive if a power facility bid
up their price, assuming that current industrial consumers could outbid bio-power facilities. So
this screen eliminates agricultural crops.
Timber in the form of cordwood also drops out. On a BTU basis, stumpage (the price of
unharvested timber stands) of aspen, Minnesota’s largest wood crop, is at least twice what
Minnesota’s power plants pay for coal (DNR, 2005; Jacobsen, 2006; and EIA, 2006b). That
doesn’t take into account harvesting and trucking, which are 89% of the cost of wood delivered
to the mill. Delivered prices of other species, like birch, have been lower than aspen but still
higher than coal on a BTU basis.
$7.00
$6.00
$5.00
$ per MMBtu
$4.00
$3.00
$2.00
$1.00
$0.00
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Aspen Birch Coal
Figure III-2: Price comparison: aspen and birch pulpwood
on the stump and coal delivered to MN in 2004
Wood waste, on the other hand, may be affordable for biomass fuel. Wood is the densest and
most transportable form of biomass available, and loggers are eager to sell harvest residues, like
limbs, lily pads and tops, and unmerchantable species, that they have to harvest to meet
Identifying Effective Biomass Strategies: Page 33
Quantifying Minnesota’s Resources and Evaluating Future Opportunities