SunEdison commissions Colorado PV plant
In late December, SunEdison announced the start-up of another PV plant, its 8.22-MW facility in Alamosa, Colo., ahead of schedule. The facility—the largest solar PV plant in the U.S. supporting substation loads for a major public utility—is expected to generate about 17,000 MWh annually. The solar plant was financed and built and will be maintained by SunEdison pursuant to an agreement with Xcel Energy under which the utility will buy both the plant’s output and the renewable energy credits it generates for the next 20 years.
The plant, on an 80-acre site near an Xcel substation, is notable for its use of three distinct types of solar technologies: a single-axis tracking array, a fixed-mount array, and a dual-axis tracking array with PV concentrator technology.
According to Karen Hyde, VP of resource planning and acquisition at Xcel Energy, “This is a unique facility—three types of solar technologies have been deployed in parallel. Performance monitoring will allow us to study the system’s performance and evaluate the relative benefits of each technology over the system’s expected 20-year lifespan.”
Big concentrating solar plant proposed
A consortium of southwestern electric utilities has issued a request for proposals (RFP) by developers to build a large (100-MW to 250-MW) solar thermal power plant in Nevada or Arizona by 2012.
Members of the Southwest Energy Service Provider’s Consortium for Solar Development would buy all of the plant’s output. Bids are due March 19 of this year. The consortium consists of Arizona Electric Power Cooperative, Arizona Public Service Co. (the group’s coordinator), Southern California Public Power Authority, Salt River Project, Tucson Electric Power, and Xcel Energy.
The RFP specifies that the plant must employ concentrating solar power technology like that used by Acciona Solar Power’s 64-MW Solar One project, which recently came on-line in southern Nevada (POWER, December 2007, p. 40). It also states that projects including thermal energy storage will be given preference. More information is available at www.aps.com.
Super Boiler celebrates first anniversary
An industrial boiler that operates at 94% thermal efficiency and produces fewer emissions than conventional boilers has operated successfully for a full year, producing high-pressure steam for a manufacturer of rubber parts. DOE officials attended the first birthday party for the “Super Boiler” (Figure 6) on November 30 at Specification Rubber Products Inc. in Alabaster, Ala.
6. Happy birthday. The DOE-sponsored Super Boiler, developed by the Gas Technology Institute and Cleaver-Brooks Inc., recently completed its first year of service, racking up more than 6,000 hours of operation at a thermal efficiency approaching 94%. Courtesy: DOE
Since 2000, the DOE’s Industrial Technologies Program has subsidized the basic research that led to the Super Boiler to the tune of $4.2 million. The unit itself was developed by the Gas Technology Institute and its partner, Cleaver-Brooks Inc.
The boiler geometry incorporates a two-stage firetube design that is both compact and very efficient. Key innovations (Figure 7) include a transport membrane condenser (TMC), a humidifying air heater (HAH) that extracts sensible and latent heat from the boiler’s flue gas, compact convective zones with intensive heat transfer, and a staged/intercooled combustion system that minimizes emissions.
7. Saving Btus. The Super Boiler’s unique flow path improves its combustion efficiency. Source: DOE
The boiler at Specification Rubber Products is a single-stage, 300-hp, gas-fired TMC/HAH boiler that has been running 24 hours a day, five days a week with promising results. After more than 6,000 hours of operation, its efficiency converting fuel to steam has consistently been in the 93% to 94% range, producing annual gas savings of nearly 13%.
The Super Boiler’s unique design, which incorporates high-intensity heat transfer using extended-surface firetubes, has exhibited heat transfer coefficients about 18 times greater than those of boilers using plain firetubes. In laboratory tests, the technology reduced NOx emissions to as low as 3 ppm while maintaining CO levels below 10 ppm across the firing range. Maintaining excess-air levels at 3% or lower has delivered better efficiency than low-NOx burners that employ flue gas recirculation or high amounts of excess air.
With one year of successful operation under the Super Boiler’s belt, the next step in its evolution is further testing. New hosts will be the fruit-juice maker Clement Pappas & Co. (Ontario, Calif.) and Third Dimension Inc. (West Jordan, Utah), a manufacturer of boxes and packaging. Steam generation typically accounts for about one-third of the energy used by manufacturers.
Small fuel cell uses JP-8 jet fuel
Two core technologies developed at the DOE’s Pacific Northwest National Laboratory (PNNL)—a fuel desulfurization system and a fuel reforming system—were instrumental in the demonstration of a 5-kW fuel cell running on JP-8, a popular military fuel.
Portable fuel cell power units are quieter, cleaner, more reliable, easy to maintain, and up to three times more efficient than internal combustion engines such as diesels. But they are challenged by JP-8 fuel’s high sulfur content. The fuel desulfurization and reforming systems developed at PNNL reduce the sulfur content of JP-8 and generate a hydrogen stream compatible with an integrated fuel cell (Figure 8).
8. Stand up and salute. Converting JP-8 fuel to hydrogen for use by an onboard fuel cell has many potential applications, especially in the military. Source: PNNL
Although they are being developed for military use, the desulfurization and reforming technologies can be used with different liquid fuels to provide portable power almost anywhere that small size and high performance are important. For example, researchers at PNNL are looking to make the desulfurization technology compatible with diesel fuel.
The fuel cell–centric auxiliary power unit (Figure 9) is modular and can be reconfigured for a wide range of uses. Researchers envision using the technology to supply auxiliary power and heat for long-haul commercial trucks, which would eliminate the need for and cost of running less-efficient engines while the vehicles are stopped. Battelle, which operates PNNL for the DOE, operated a prototype system demonstrating these technologies during the three-day 2007 Fuel Cell Seminar last fall. During the demonstration, an integrated 5-kW electric power system successfully powered area lights and a commercial refrigerator.
9. Clean and compact. This 5-kW electric power system incorporates a PNNL-developed fuel processor. Source: PNNL
The unique catalytic hydrodesulfurization process developed by PNNL removes sulfur from JP-8 fuel using syngas as the co-reactant in place of hydrogen. Gas-phase operation of the process allows for a significant increase in throughput as well as a decrease in operating pressure compared with conventional technology. The process doesn’t require consumables or periodic regeneration.
Email
Comments
Print
Reuse
