COLUMBIA, South Carolina — The University of South Carolina decided the best way to meet its challenge to incorporate renewable energy was to use readily accessible fuel in a cutting edge plant right on campus. The biomass energy cogeneration plant, the first of its kind in the U.S., uses abundant wood fiber for feedstock.
The university weighed many options as it looked for ways to reduce costs for steam and electricity. Jeff Morehouse, a U.S.C. mechanical engineering professor, and other U.S.C. faculty and staff who were tackling the problem learned through Johnson Controls Inc. of Nexterra, a Canadian company. Nexterra could supply the components for a plant that could process wood waste material into syngas, a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Jeff was sold on the technology and became an advocate.
“We were looking for something which did not use a fossil fuel, such as natural gas,” said Jeff. “We wanted something using a renewable fuel and not just to create steam but also electricity. High temperatures generated by syngas enabled us to get high pressures to make electrical power – enough to run the complete plant, plus an equal amount more to use for the local grid. The waste wood and gasification was a good combination, and it met all our energy and ecology criteria. Another requirement was the use of local South Carolina resources, which were abundantly supplied through area wood industries.”
“Everything on our checklist was met by this plant,” said Jeff. When it came down to it, there were few alternatives that would meet all the requirements. We had few other options despite all our searching.”
The model for the university plant was a plant in Canada. The only major difference was the Canadian plant was in a remote location; the university is located in the heart of Columbia, just a few blocks from the State Capitol building.
The U.S.C. biomass energy plant supplies a small portion of the electricity and a large part of the steam heat for about 100 buildings on campus. It was designed with an additional electrostatic precipitator filter to further control air pollution. “We certainly are well within the pollution standards,” said Jeff.
The facility becomes less cost effective as transportation costs rise for wood material. “Anything more than 40-50 miles becomes uneconomical,” explained Jeff. “The renewability concept falls apart at that point and is offset at that point because of how much gasoline and diesel fuel is being used (for trucking). As a result, this is a smaller-scale type of operation. It would work if it were able to be replicated every 50 miles but cannot be something on the scale of a large coal plant.”
The U.S.C. campus is over 200 years old, and some of its infrastructure is old, so in the process of putting in the new plant the university also needed to upgrade some underground pipes, valves and other equipment.
Plant Operations
The plant was designed by Johnson Controls in partnership with Nexterra. The project was part of a performance contract with Johnson Controls to basically offset natural gas usage in existing energy plants by approximately $1-2 million annually, depending on gas prices.
The feedstock for the plant is wood chips, hardwood and softwood. The chips come from logging slash and similar debris as well as small diameter, low value trees. The chips must be a certain specified size with moisture content no more than 35%-40%.
The wood feedstock is heated in chambers to 1,500 degrees. Heating the wood fiber produces syngas – the process is called gasification – that is siphoned off and burned to generate steam and electricity. The steam is used for heating, hot water conversion or for domestic hot water uses.
The plant, which began operating in January, is located on the edge of the campus. It is contained in a multi-level, 34,000-square-foot building that was constructed on a site that formerly was a parking lot. From the outside it appears quiet, inconspicuous.
The plant can accept about 10 truck-loads of chips per day. Outside, where the trucks are unloaded, the chips are fed into a hopper, and a conveyor carries the material to a storage area inside the plant. The interior storage area can hold enough wood to run the plant for four to six days.
The feedstock moves via conveyor out of storage and is transferred to screw-type conveyors that deliver it to the three gasifiers to be heated and pyrolyzed. The ash settles to the bottom and is removed by conveyor. The syngas is collected and burned in a furnace/oxidizer, where air is introduced to support combustion. A heat recovery boiler system produces steam at the rate of about 60,000 pounds per hour. The high pressure steam passes through a turbine-generator to produce electricity, about 1.5 megawatts, and the resulting low pressure steam is then circulated through the campus system to provide heat and hot water.
“When this plant is operating at maximum capacity, we anticipate significant savings for the university simply by not burning natural gas in the existing boilers,” said Quinton Bolin, superintendent of the university’s energy facilities. “The energy savings will actually make the payment against the loan taken out for the plant, and it will pay itself back over the contract period.”
During times of low demand, the plant can supply 100% of the university’s steam requirements, according to Quinton. During times of peak demand, such as the winter, it can still provide about 80%.
Of course, in a project of this scope, mechanical issues arise. “With this new type of design, working the bugs out has been a test for awhile,” said Quinton. He formerly worked for International Paper, and other plant personnel have experience in coal-fired power plants.
“I definitely see the biomass type of power generation that we have at our plant as the way of the future,” said Quinton.
Any carbon-based material can be gasified, noted Quinton, as long as the feedstock does not contain any chemicals that would interfere with the process. “Naturally, you wouldn’t want to gasify tires, though I’m sure it could be done,” said Quinton. “Wood and bark are both relatively free of contaminants, are carbon-based, and gasify very well.”
By-products of the gasification process are ash and water vapor, which exits through a smoke stack. “Carbon dioxide leaves the stack at the same time,” said Quinton. “But since this is a carbon-neutral process, no more carbon dioxide is released to the atmosphere than the trees have absorbed during their life cycle. For this reason the operation can be considered completely ‘green.’ ” Ash is sent to a landfill, but the university is looking for outlets for ash, such as using it as a soil amendment or in construction material.
Wood fiber is supplied to the plant exclusively by Palmetto Forest Products, which has chipping and grinding operations. The company performs clean-up work on logging jobs, going in after the timber is harvested to chip or grind the slash material left behind. It also chips and grinds the material it cuts from thinning and other jobs.
Nexterra
Nexterra, based in Vancouver, British Columbia, manufactures and supplies biomass gasification systems and solutions. The company, led by president and CEO Jonathan Rhone, was founded in 2003.
According to Nexterra, its technology has significantly cleaner emissions and is more versatile from a fuel flexibility standpoint. In addition, syngas can be used for a larger variety of applications — including internal combustion engines.
“We saw this technology as having tremendous promise,” said Jonathon. “At the time, Johnson Controls was growing their building solutions business and looking at renewables. Their customers at public institutions increasingly demanded solutions based on renewable energy. U.S.C. looked like an excellent choice for a first project where we could sell them our technology and they would package it, guarantee it and install it.”
Nexterra had experience in industrial applications, but U.S.C. was its first foray into the public institution market. It is a huge opportunity.
“The public market, including universities, hospitals, state and federal governments, all have central heating plants, and the value proposition for the end user is simple,” said Jonathon. “Biomass on an energy basis is a lot less expensive than natural gas, so the difference between natural gas and the cost of biomass is what is driving the economics of these projects.” Even allowing for transportation costs, biomass still costs less, he added.
These type of plants typically burn natural gas or some other type of fossil fuel, so changing to biomass can reduce and stabilize energy costs. In addition, if a plant converts from fossil fuel to biomass, it reduces its carbon ‘footprint’ because biomass is carbon neutral.
“Many universities are interested in developing clean energy technology solutions,” said Jonathan. “They also like the idea of running their campuses on locally purchased energy sources,” he added, because it supports local economies.
“Universities are doing some extraordinary things across all of their operations in terms of sustainability and reducing their carbon footprint,” said Jonathan, “from fleet management to adoption of energy-efficiency technology, reducing the amount of electricity they consume and water consumption. This is part of a larger trend for universities to be leaders in sustainability. It is quite important right up to the top leadership.”
Nexterra also is involved in a project with the Oak Ridge National Laboratory in Tennessee. This is a much larger project for the company because it is supplying fuel handling and storage equipment, the gasification system, heat exchangers, all of the air emission control equipment and the plant controls. The plant at Oak Ridge will utilize waste wood material for fuel.
Nexterra has a strategic alliance with GE to condition syngas so it meets the performance specs of GE’s high efficiency gas engines.
“We’re marrying our gasifiers with GE-Inbacher, one of the largest manufacturers of small-scale, high-efficiency gas engines,” said Jonathan. “This will produce a new generation of biomass power plants that is going to be significantly higher efficiency than conventional wood fired, combustion to steam heat generation. We’ll be able to achieve efficiencies of up to 60% in cogeneration mode…compared to combustion to steam applications with efficiencies typically in the low 20% range.”
The scale of these biomass power plants would be 2-10 megawatts. They would be targeted at essentially the same markets, public institutions and industrial plants.
Alternative energy like wind and solar power may not be a good fit in many states that have abundant biomass, noted Jonathan. “That’s an important target for us from a geographic standpoint. The Carolinas are going to be an important market for this technology.”
“The U.S.C. project has generated tremendous interest as have our other projects,” said Jonathan. “This is established and ready-to-use technology with global applications.”
Morbark Chipper Helps Company Tap New Market
The recession has companies and the people working for them wondering what their next move might be.
Palmetto Forest Products, based in Moncks Corner, S.C., acted quickly when the housing market collapsed in the past year or so. It closed its lumber remanufacturing business for now and has found a new, growing niche: chipping wood and supplying it to paper mills and energy plants. The new enterprise is doing work in Georgia and South Carolina.
One customer is the University of South Carolina, which recently opened a new biomass gasification plant, the only one of its kind in the country. The USC biomass gasification plant heats wood fiber to create syngas, a mixture of carbon monoxide and hydrogen that is used for fuel to make electricity and steam.
“Our relationship with the USC biomass plant is going great,” said Chris Riley, 34, owner of Palmetto Forest Products.
Palmetto Forest Products does not perform round wood logging operations. Besides some clear-cutting, thinning and understory clearing, it goes onto jobs after other loggers in order to grind or chip the slash and debris left behind. “We’re trying to make it so we utilize all the wood fiber,” said Chris.
The company is equipped with a Morbark 4036 chipper and two Morbark 6600 wood hog horizontal grinders. Felling is done with three John Deere 843J feller-bunchers. Other equipment includes two John Deere 648H skidders and a John Deere loader.
The USC biomass plant has proven to be a valuable new market for the company. In fact, the plant is willing to buy more fuel chips if Palmetto Forest Products can supply them.
“We were so glad we found this new source for our product,” said Chris. “Ken Sheppard at American Forest Management was instrumental in having all this come about for us and USC. They manage people’s land, while USC likes our product. Ken knows he has to keep wood flowing to us in order to keep chips flowing to the university. This took Ken four years to get up and running, and it’s all working out quite well for all involved so far.”
American Forest Management provides forest management consulting and other services. It manages over 4 million acres for institutional investors and private non-industrial landowner clients.
