Biomass bridge Gasified wood chips and corn cobs are replacing natural gas at Benson ethanol plant

By E. M. Morrison

Benson, Minn. — A Minnesota ethanol company is building a biomass bridge to an energy self-sufficient future.
 

A biomass gasifier, the large cylinder rising in the center of the photo above, will replace about 20 percent of the Chippewa Valley ethanol plant's natural gas consumption when it goes online in early 2008. Eventually gasification will supply all of the plant’s energy needs.

Chippewa Valley Ethanol Company will gasify wood chips, corn cobs and other biomass to run its plant. The system will go on line early 2008, replacing about 20 percent of the company’s natural gas consumption. Eventually, biomass gasification will supply nearly all of CVEC’s energy needs.
 

Gasification will cut the company’s exposure to volatile natural gas prices, says Bill Lee, CVEC general manager. Just as important, Lee says, powering the 45-million-gallon refinery with biomass will produce ethanol that’s more environmentally friendly.
 

Biomass gasification will also set the stage for the transition from starch-based ethanol to cellulosic ethanol. “This is the next step” in the evolution of renewable transportation fuels, Lee says, a “bridge” stage “before we get to cellulosic ethanol.”
 

Three-phase project
Gasification converts solid organic material, such as plant residues, into a low-Btu gas that can be burned like natural gas in a furnace, turbine or engine. CVEC’s three-phase gasification system
is being designed and built by Frontline BioEnergy of Ames, Iowa. The Phase I pilot plant broke ground last July. It will supply synthetic natural gas, or syngas, to a retrofitted boiler that generates steam for distillation and other processing steps.
 

The pilot gasifier will consume 35 to 70 tons per day of biomass and will accommodate a range of feedstocks. “Initially, we will use wood chips,” Lee says. By next summer, the company expects to be gasifying corn cobs and distiller’s grains. CVEC will also experiment with other biomass feedstocks, such as corn stover and perennial grasses, Lee says.
 

In Phase 2, CVEC will install additional syngas-cleaning technology. In the final phase, the gasification system will be scaled up to fuel the entire plant. The full-size system will consume about 250 tons of biomass daily, furnishing 90 percent of the plant’s energy needs.
 

The entire project will take three years to complete.
 

Volatile gas prices spark innovation

High and increasingly unpredictable natural gas prices prompted the farmer-owned ethanol-maker to look for alternatives. Natural gas is the plant’s second biggest expense, after corn, running $15 to $20 million a year. “Two years ago, we were seeing natural gas prices of 8, 10, 12 dollars” per million Btu, Lee says. After falling in the summer of 2007 to around $4/MMBtu, natural gas prices again climbed above $7/MMBtu last fall.

“It looked like the less we depended on that energy market, the better,” says Brandon, Minn., farmer Gene Fynboh, a longtime CVEC board member. “We have biomass resources in our own backyard that can fire the plant.” Instead of sending energy dollars to Canada or Texas, he says, “we thought it would be better to spread $16 million around our own communities.”
 

CVEC also expects low-carbon fuel standards to emerge, creating demand for ethanol made with fewer fossil fuel inputs. Already, California has set a goal of cutting the carbon intensity of transportation fuels at least 10 percent by 2020.
 

Running a dry-grind mill on biomass power nearly doubles corn ethanol’s “energy balance,” the volume of ethanol produced per fossil-fuel unit, according to the Great Plains Institute, a renewable energy policy group. As carbon emissions trading develops, Lee says, “a plant running on biomass will have an advantage.”
 

Developing biomass markets

One of the main difficulties in using biomass power is the lack of an efficient feedstock supply and distribution infrastructure, Lee says.
 

“The biomass industry is very immature. There’s a vast, untapped supply of these materials, but they are hard to handle.” Nobody really knows yet what biomass will cost to collect and transport, he says, but one thing is certain: “The marketplace is dynamic.” As demand for biomass builds, “smart people will figure out how to manage it well and costs will come down.”
 

Minnesota’s farmer-owned ethanol co-ops could serve as a good model for new biomass-supply ventures, he says, aligning the interests of biomass producers and users.
 

AURI, the University of Minnesota, and others are now working on improved methods for collecting, pre-processing and storing biomass. AURI and Minnesota Corn Growers and Soybean Growers, for example, are sponsoring research on compacting bulky, lightweight crop residues into dense blocks or pellets that are easier to transport and store.
 

The USDA North Central Soil Conservation Research Lab in Morris is working on environmentally-sustainable ways to remove corn stover and other crop residues from the soil. Minnesota researchers are also investigating biomass energy crops, such as high-yielding prairie grasses, fast-growing trees, sorghum and miscanthus.

Growing a biomass industry

Minnesota has all the ingredients for a successful biomass-energy sector: feedstocks, research and emerging end users, says Michael Sparby, AURI project director. CVEC is the third Minnesota ethanol plant to adopt biomass power. Corn Plus in Winnebago is burning ethanol byproducts in a fluid bed reactor. Central Minnesota Ethanol Co-op in Little Falls isgasifying waste wood. Other Minnesota organizations are gasifying grass-seed chaff, turkey litter and corn stover.
 

Pioneering enterprises like these will spur development of a biomass industry and create opportunities for entrepreneurs and innovators, Sparby says. That’s a prerequisite for the ultimate goal — making ethanol and other renewable products from cellulose, the woody fiber found in all plants.
 

“You can’t have a cellulosic ethanol industry unless you have a biomass market first,” says Lee, who often speaks to farm and industry groups about ethanol trends. By analogy, “15 years ago there wasn’t much ethanol yet, but there certainly was an existing corn market and a lot of cheap corn.”
 

It’s clear that cellulosic ethanol technology is on the horizon, Lee says, “but it’s going to take some time. While we’re waiting, let’s transition to biomass power.” ■

Innovative companies in an innovative town
Benson, Minn., population 3,300, is home to several agribusinesses doing innovative things with renewables.

Fibrominn, a 55-megawatt power plant, is the nation’s first to generate electricity from poultry litter. Another local company, Future Products, manufactures apparel made of Ingeo, a cloth spun from corn. Chippewa Valley Ethanol Company is the state’s second ethanol plant to install biomass gasification. AURI has worked with all three Benson companies. ■