Biomass Feasibility Project Final Report - Xcel Energy

for a full-time permit is more complicated. Gensets burning B100 (100%) biodiesel emit far fewer
pollutants, like hydrocarbon, sulfur, carbon monoxide and particulates, than generators using
petro-diesel (although NOx emissions may be higher). Thus standby generators burning biodiesel
perhaps could operate more hours per year without exceeding permit restrictions. If that were
the case, utilities and their large commercial and industrial customers could treat standby
generators as dispatchable peaking generators.
A recent report in The MMUA Resource reviewed a number of diesel generators operated as
peaking plants by municipal electric cooperatives. Attracted by the high lubricity of biodiesel
fuel as well as the chance to support local biodiesel industries, the co-ops have begun to add
up to 20% biodiesel into their fuel mix. Last year, locally-owned municipal power plants
generated 932 megawatt hours of electricity with biodiesel.
Besides standby and peaking generators, baseload generators are being tested using biodiesel.
McMinnville Electric, in Tennessee, has been running long term tests with B100 in a 2 MW
generator. The somewhat lower BTU content of the B100, as well as its somewhat different
chemical composition and emissions profile, have required minor adjustments to equipment.
The New York Power Authority recently tested biodiesel in the boiler of the 885 MW Charles
Poletti Power Project in Astoria, NY, in mixtures ranging from B5 to B20. The Authority reports that
efficiency rose and emissions fell.
Using the eGRID database, we estimate the fuel oil consumed by all Minnesota electric
generating facilities in 2004 at approximately 63,970,000 gallons, close to the 63,150,000 gallons
of our annual biodiesel production capacity. We don’t expect utilities to use 100% of our
biodiesel production as a substitute for petro-diesel, but there is plenty to add to the fuel mix of
standby and peaking generators, which burn approximately 2.2 million gallons per year. Even if
they used pure, unmixed biodiesel, they would consume just 3.5% of the state’s biodiesel
capacity.
OPPORTUNITY 7: ANAEROBIC DIGESTERS
The attractiveness of anaerobic digesters will depend in large part on the non-energy benefits
provided by the digester and on the ability of farmers to monetize those benefits. Savings from
reduced use of fertilizers and herbicides may be nearly as large as revenue from electricity sales.
From a strictly cost of electricity perspective, anaerobic digesters typically result in electricity
costs of around 12¢/kWh. However, if the cost avoidance (and resulting operational benefits)
created by the digestion process are included, the resulting cost of electricity (and therefore the
cost that the owner would need to recover in order to be financially whole) is more on the order
of 4¢/kWh.
Identifying Effective Biomass Strategies: Page 159
Quantifying Minnesota’s Resources and Evaluating Future Opportunities