WASTE NOT, WANT NOT: American Crystal uses NASA technology to turn sugar beet leftovers into energy
MOORHEAD, Minn. -- In a bid to make better use of several thousand tons of sugar beet waste product each year, American Crystal Sugar Co. this year will test a technology originally developed to help astronauts on Mars generate energy from plant ...
MOORHEAD, Minn. -- In a bid to make better use of several thousand tons of sugar beet waste product each year, American Crystal Sugar Co. this year will test a technology originally developed to help astronauts on Mars generate energy from plant waste.
Each year, Crystal Sugar must pay millions of dollars to properly dispose of tailings, the parts removed from the sugar beets before they are refined into sugar. At the East Grand Forks, Minn., site -- just one of Crystal's six factories in the Red River Valley -- about 400 tons of tailings are generated each day during the sugar beet campaign, which Crystal must haul to and spread over area farmland. If the technology works, Crystal instead will be able to turn those tailings into methane gas, a burnable fuel.
Dave Malmskog, director of economic analysis and business development at ACS headquarters in Moorhead, Minn., likes the win-win possibilities.
"We could actually save money by not having to land-apply it and then take the energy from the process, in addition," he says.
A seven-story pilot plant in Moorhead is near completion now and will be ready for testing during the 2008 campaign.
A good match
The University of Florida is responsible for developing the technology for NASA, which was in search of high-efficiency models for waste management and energy creation, ostensibly for use on a future manned mission to Mars. Tabletop research proved the theory, but with ingredients measured in teaspoons, not tons. Researchers needed to develop a larger-scale test, so four years ago, they contacted Crystal to see if the company would be interested in pursuing the technology.
"They thought this might have commercial applications here on ground," Malmskog says. "They heard about the Xcel (Energy) Renewable Energy Development Fund, and then came to Crystal Sugar and said, 'If we applied for one of these grants, would you want to work with us on the project?' We thought this was potentially a very good fit for our tailings."
The grant provides $1 million for developmental projects, allowing an added potential for a $2 million grant if it can be proven to commercially viable.
The process uses microorganisms inside a series of containers loaded with tailings to gobble up the organic matter and produce methane gas in return. By controlling the temperature, moisture and pH levels in the bins, the University of Florida process markedly reduces traditional timeframes.
"It takes a certain length of time to digest this material," says Terry McGillivray, manager of technical services at Crystal. "They've gone from 30 days down to, I think, five to seven days to do the digestion."
In terms of capital costs, this acceleration could help make this process economically feasible on a commercial scale.
"Our responsibility is that we were to provide the site -- some place to do it," he says. "Originally, we were talking about using the grant money to construct a building and install the equipment, but we subsequently found a facility at one of our factories that we could utilize, and then we supply the raw materials."
The original pilot plant could fit on a standard kitchen table. The multistory Crystal project, designed to process 10 tons of tailings per week, represents a stepping stone on the way to full commercial-scale processing.
As with all new technology, there has been a learning curve.
"There have been a number of issues that have come up that we've had to work through to make sure it would work here," Malmskog says. "This is part of the scaling-up process."
Even the simplest of things can become a challenge. For example, how to get the tailings lifted up into the 25-foot-tall containers on the fifth floor of the site.
"There, with 1 ton versus 25 tons versus 400 tons of tailings -- the engineering can be completely different and can cause quite a problem," he says. "There are probably 100 things like that that you need to figure out if you want to go up to the next size."
There have been issues related to getting the bacteria-charged liquids to percolate down through the tailings, as well as preventing the flammable methane gas from exploding.
"In a little vessel, you don't really worry about the gas collection," McGillivray says. "When methane gas gets to 15 percent in the atmosphere, it's explosive, but that's not an issue in the lab. If someone opens the door, you've got plenty of ventilation and you're probably good for the day. But over here, we've had to go through and put some ventilation equipment just to ensure that we don't have any explosion hazards."
The goal of this plant is to prove the technology can be viable on a much larger scale. Testing will begin in the fall and continue into spring 2009, with different types of weather conditions and tailing feedstock.
"If it's successful, then we'll try to scale up to a mid-size," Malmskog says. "Maybe, instead of a ton-and-half a day, maybe 20 or 25 tons a day. And then if that's successful, then we go up to the commercial size."
Long range outlook
"At East Grand Forks, we could produce about 125 billion BTUs a year," he says. "We could take that energy and perhaps clean it up and sell it as green natural gas, or if we wanted to use it on site, we could pump it over to our boiler house and use it to replace coal."
There is also some talk of using it in a cogeneration unit to make electricity.
"We are a huge energy consumer, so that 125 billion BTUs could easily be used up in any one of these applications," Malmskog says. "Ideally, where I would like this to go -- where it would probably provide the most benefit -- is if we could find a way to clean it up and inject it into the natural gas pipeline."
This eliminates the disposal costs as well as Crystal's carbon footprint, while generating a "green" natural gas, which could be awarded carbon credits.
"Quite often, you can't get that credit, unless you sell it, so even if we use it ourselves, to get all three benefits, that may be where we want to go," Malmskog says.
As far as taking potential credits from farmers who are now having the tailings spread on their fields, he says that is a nonissue.
"There are no carbon credits there because it is left on top of the soil," he says.
Unless it is buried, it creates no anaerobic process and so cannot generate carbon in the soil.
The pilot plant will be capable of processing other feedstock, as well, Crystal officials think, which may allow it to generate methane gas year round.
"In the future, I'll be looking for other biomass that we might use as a feedstock," he says. "We process beets from September into the middle of May. That would leave us a good three months where the equipment would sit idle. There may be some other waste product out there that we're starting to look for."
Malmskog says he is not yet actively searching, pointing out that the funding for the pilot project was provided for processing sugar beet tailings, so he needs to complete that goal before anything else is loaded into the containers.
"If it looks good, then we'll probably do a survey of the area and see if there are more biomass feedstocks that are close enough that freighting them in wouldn't be more expensive than the value we would get from methane production."
The pilot plant project on Moorhead conceivably could lead to a commercial plant in as early as two years, Malmskog says.