Green Manufacturer - March April 2012

What is biofuel?

Biofuel is derived from the conversion of biomass directly into liquid fuel, as well as from solid biomass. Biomass is any organic material made from plants or animals. According to the U.S. Department of Energy, Energy Efficiency and Renewable Energy, domestic biomass resources include agricultural and forestry residues and terrestrial and aquatic crops grown solely for energy purposes. The department also considers municipal solid wastes and industrial wastes to be biofuel sources, although paper mills are prohibited from using them in their boilers by federal and state regulations, according to industry insider Greg Na-rum of Simpson Tacoma Kraft.

Biomass gets its energy from
the sun, which is stored in
plant leaves, stems, and roots.

Environmental benefits of biomass are that the energy is renewable, and plant matter is relatively abundant in most parts of the world. Although CO2 is released back into the environment when the biomass fuel is burned, among the selling points for using biomass as a fuel versus fossil fuels is that the CO2 released is equal to the amount that the plant adsorbed while it was growing— thus creating a carbon-neutral effect.

Some estimates are that biomass fuels currently generate about 11,000 MW, or 4 percent of the energy used in the U.S., where the most common form of biomass is wood and wood waste.

By Gabe Crognale, Contributing Writer

The International Energy Agency (IEA) projects that by 2030 glob- al electricity demand will almost double, according to a recent report, “The Business of Innovating: Bringing Low-Carbon Solutions to Market” (www. pewclimate.org/docUploads/LowCar bonInnovation.pdf).

With the environmental stigma associated with generating power with fossil fuels, whether at large power generation plants or on-site industrial plants, a number of resourceful manufacturers are looking to turn their solid waste streams into clean, renewable biofuel power sources.

Biofuel can be used to generate electricity, heat, or steam needed to operate a manufacturing plant. Increasingly, modern biofuel technology incorporates cogeneration capabilities, also called combined heat and power (CHP), to produce both electricity and heat or steam from one fuel source. Cogeneration is considered especially efficient because it maximizes the energy captured and minimizes the energy released into the environment as hot air or hot water and wasted.

For one particularly energy-intensive industry—pulp and paper manufacturing—biofuel has long been a fuel of choice. Paper manufacturers have used wood lignin (black/spent liquor recovered from the pulping process) as a fuel in recovery boilers since the 1930s, along with burning solid wood residue for heat recovery. The technologies used in such systems are direct-firing, co-firing, gasification, pyrolysis, and anaerobic digestion.

Many paper manufacturers are thriv-
ing producers of bioenergy that they
sell to their local utilities. In regions
where power costs have been too low
historically to justify investments in co-
generation, green energy credits have
prompted some mills to do so recently.
In some cases, the credits render it
more profitable for the mills to sell the
power they generate on the open mar-
ket than to use it themselves.

Lessons Learned From
Paper Mills

The efforts that pulp and paper companies have devoted to sourcing biomass at their facilities warrant a closer look to evaluate their level of success. Other industries may glean lessons from their initiatives as well.

Paper manufacturers sourcing biofuel include Verso, Simpson Tacoma Kraft, and Mead Westvaco.

Verso Paper Corp. Verso is a North American producer of coated papers, used primarily in magazines, catalogs, and advertising literature.

On Jan. 9, 2012, the Memphis, Tenn.-based manufacturer announced the completion of a $45 million renewable-energy project at its pulp and paper mill in Quinnesec, Mich.

Design upgrades to the mill’s existing combination boiler, which already has been burning biomass from waste wood sources, will enable it to deliver an additional 28 MW of green energy for mill consumption, bringing to 95 percent the share of electricity it will generate from renewable, carbon-neutral, wood-based biofuel. The mill anticipates that the upgrade will reduce carbon emissions by 147,000 metric tons per year.

System upgrades also include a new, energy-efficient turbine generator and a biomass handling system to expand the mill’s capabilities so that it can process residual wood, such as treetops, limbs, and bark, in keeping with Forest Stewardship Council (FSC) forest sustainability standards.