Building on its Biomass Base
The biomass industry is flourishing in and around Sacramento, Calif., where new biomass-based technologies are nurtured and innovative proven processes are embraced.
The center, operated in conjunction with Renewable Energy Institute International, provides a site for evaluating the performance of renewable energy and fuels technologies with respect to robustness, safety, energy efficiency, environmental effectiveness and other key performance specifications. "If you don't have the answers to those questions, you're not going to get anybody to give you money," says Jodie Crandell, senior project manager for Technikon. The four companies-Davis, Calif.-based Sierra Energy; PEAT International, which operates in locations such as Florida, India and Taiwan; Ternion Bio Industries, headquartered in San Jose, Calif.; and a fourth company that declined to disclose any information for this article-are working together on complementary and sometimes competitive technologies, even sharing expertise.
The center has been operating for about 1˝ years and is funded by the U.S. Department of Defense. Typically, the U.S. DOE solicits grant applications to build large-scale plants, but start-up companies that haven't proven their technologies don't often qualify. "The smaller guys, who don't have any data or information or a place to have people come in and look at their equipment, really kind of get squeezed out of the process at this point," says George Crandell, vice president of Technikon operations and Jodie's husband. "We're helping more and more small guys become successful." Companies using the space save money on facilities, electricity and other aspects of research and development that are already available at the RETC. It's a unique model of how to leverage government funding to accelerate the commercialization of pilot-scale technologies, Crandell says.
The four companies together have made in-kind contributions of about $4 million in areas such as personnel and equipment, according to Technikon. Four projects are all Crandell can support on current funding, but there are four or five waiting to use space in the center. A formal group reviews projects and determines who will occupy the RETC, and Crandell has found that he doesn't have to look far to find companies looking to use space. "We're also finding that venture capitalist groups are circling like vultures around us," he laughs. "They see us as a very good sorting and screening mechanism."
Technikon also offers expertise in project management, finance, and chemical and mechanical areas, among others. The company does not have a large area for biomass storage and handling at this point because the systems currently occupying space are not big enough to warrant it. Process testing is also available for Technikon's clients in the areas of throughput, scalability and capacity, among others, along with emissions and biofuels testing.
"We initially thought that we'd just open the doors and let people bring equipment in and we'd help them test it," George Crandell says. "As we've been moving forward, we really realized that we wind up helping them do equipment development and modifications, so we're getting more into that."
Projects in the Center
Sierra Energy is using its space in the RETC to develop its patented Fastox gasification system that modifies iron-making blast furnaces, converting exhaust gases into nearly pure syngas. Currently, the team is using a blend of charcoal briquettes (80 percent), coke and limestone to simulate the waste and hopes to eventually use municipal solid waste (MSW), according to George Crandell. Sierra is not converting its syngas at this point, but has an agreement with a New Zealand-based company that produces ethanol from syngas. That company will set up its production system in the RETC after the Sierra system is scaled up from the current 1-ton-per-day input level to 10 tons per day, Crandell says. That scale-up should happen in about three months, but it may take longer for the ethanol system to move in. The gasifier is currently producing a syngas composed of 30 percent hydrogen and 70 percent carbon monoxide, by adding water and steam to the bottom of the reactor, Crandell says. An existing blast furnace could consume about 30,000 tons of MSW per day. "It's very scalable because [the blast furnaces] already exist at the size [Sierra Energy] is starting with, all the way up to 30,000 ton-per-day sizes," Crandell says. "The technology is textbook, except for their modifications to it."
PEAT International is working on its plasma torch gasifier, feeding it mostly wood chips. "It's a high-temperature conversion of pretty much anything to a synthesis gas," Jodie Crandell says. An electricity generator with the capacity to produce 75 kilowatts of electricity is hooked up to the back end of the system. "We actually make more syngas than the generator can handle," George Crandell says. The system is operating on about 1˝ tons of wood chips per day and will use rice straw in the near future, but the company is also working with Sacramento County to permit plasma gasification of MSW or medical waste, he says. "The very interesting thing about that is the county wants that data as much as we do because people keep proposing plasma furnaces in our area and they feel uncomfortable that they don't know anything about it," he says.
Ternion is testing its 32-foot algae photobioreactor that can eat up to 28 tons of carbon dioxide per month. "They don't have a partner for the algae back end yet," Crandell says. "They're a good partner for someone who wants to make algae oil." Each bioreactor is the equivalent of about 2˝ acres of pond and the company is looking into ganging several together, he says.
While the four technologies in the center don't currently compete, there could be friendly competition in the future, depending on the types of systems that are chosen to utilize the space. "It's up to them if they don't want to come in because they're worried about the other guy seeing what they're doing," George Crandell says.
Waste Wood to Watts
Since 1989, Woodland Biomass Power, owned by DTE Energy, has generated electricity for the grid from locally sourced woody biomass, including agricultural residues and urban wood waste. About 60 percent of the feedstock comes from landfills, 35 percent from agricultural sites and 5 percent from a free local wood drop-off site, according to Kirk Bingham, environmental coordinator for the facility in Woodland, Calif. Residents and commercial operations can drop off their wood waste such as fencing, boards and wood furniture. While that feedstock is free for the facility, the wood waste that comes from the landfills and agricultural sites is not. That material, on average, costs about $27 per ton, but can range from $17 to $42 per ton, depending on the material and the demand for it, Bingham says. If not used, most of the feedstock material would be landfilled or open-field burned.
The plant's circulating fluidized bed combustor requires about 650 to 800 tons of ground wood per day, depending on its moisture and quality. While the purchased waste wood usually is already ground, an on-site portable grinder processes the local drop-off feedstock about once per month. A majority of the company's 27 acres is used to store the processed wood on-site.
The steam produced during combustion is run through a steam-driven turbine, generating about 28 megawatts (MW) of electricity per hour. Three MW are kept to power the equipment at the facility, while the other 25 MW are sold to local utility Pacific Gas and Electric Co. Woodland Biomass has the capacity to sell the steam it produces, but chooses not to, Bingham says.
Effluent to Energy
Each day, 165 million gallons of wastewater come in to the Sacramento Regional Wastewater Treatment Plant in Elk Grove, Calif., and through anaerobic digestion of the separated biosolids, methane is generated and turned into electricity for the local grid. But it's not quite that simple.
"We have a couple of unique solids disposal processes that a lot of plants don't have," says Mike Donahue, senior civil engineer in the Sacramento County Regional Sanitation District Operations group. First, the wastewater goes through bar screens and grit tanks to remove large objects, dirt and rocks. Then, the solids are separated from the water through two processes. Primary sedimentation settles out all the large, heavy biosolids, and the lighter solids are consumed in a biological reactor by 10 or more naturally-occurring microorganisms, Donahue explains. Liquid oxygen produced on-site is injected into the reactor, resulting in a much smaller footprint. The secondary solids are then collected in secondary sedimentation tanks.
While the primary sludge is 3˝ percent total solids, secondary sludge, only one-half percent total solids, needs thickening before anaerobic digestion. That is done through either dissolved air floatation thickeners or gravity belt thickeners, both common processes at wastewater treatment plants, Donahue says. After the secondary sludge is thickened, it is mixed with the primary sludge and sent to the anaerobic digesters.
The plant has five primary digesters where the sludge spends the majority of its 20-day detention time. From there, all the sludge is combined in the blending digester. Bacteria in the digesters-the type commonly found in anaerobic mud or the stomachs of ruminant animals-break down the organic compounds while 97-degree Fahrenheit temperatures cook off the methane gas.
About 1,700 cubic feet of methane per minute (2.5 million cubic feet per day) is sent from the digesters to the neighboring Sacramento Municipal Utility District power plant and used, along with natural gas, to generate enough electricity to power 5,500 homes each year. In addition, SMUD sells steam back to the treatment plant to heat the anaerobic digesters. The methane has to be scrubbed down to 40 parts per million of hydrogen sulfide before it's transported to the power plant.
"But at the end of the day, we're still left with 75 dry tons of digested solids," Donahue explains. Thirty percent of that is sent to a nearby Synagro plant, where it's pelletized for use as fertilizer on local farmland. The other 70 percent is pumped into 125 acres of facultative ponds where it stays and breaks down further for about five years, he says, to about 40 percent of its original volume. Pond solids are dredged during the dry summers and injected into one of three 40-acre permanent biosolids disposal fields, lined to protect the groundwater. The storage ponds with permanent on-site disposal, combined with the production of biosolids pellets are what make the facility's process unique, Donahue says.
Technikon, Woodland Biomass and the Sacramento Regional Wastewater Treatment Plant are all stops on a tour scheduled in conjunction with Biomass Magazine's Pacific West Biomass Conference & Expo being held Jan. 11-13 in Sacramento. BIO
Lisa Gibson is a Biomass Magazine associate editor. Reach her at email@example.com or (701) 738-4952.