May-June 2011

Combined Power Provider

Increasing demand for turbines and microturbines—particularly among small commercial and industrial customers—reflects a growing acceptance of distributed energy.

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While the last two years have been slow for the installation of turbine and microturbine technology, those who manufacture and rehabilitate the systems say the market is now experiencing an uptick.

One such observer is Jim Crouse, executive vice president for Capstone Turbine Corporation. He says the market for microturbine technology continues to grow. The company’s product line includes various sizes of microturbines, including a 30-kW, 65-kW, and 200-kW. Products based on the 200-kW turbine are also available in 600-kW, 800-kW, and 1-MW configurations. The company also makes a dual-conversion UPS with a microturbine built in.

“Most of our smaller customers—the hotels, hospitals, commercial office buildings, and small industrial customers—are looking at distributed energy and CHP [combined heat and power]; they’re not getting into the power business because they want to be in the power business,” says Crouse.

Photo: Capstone Turbine Corporation The turbines provide the heating and cooling for the Library and Pavilion through a CCHP application.

“They’re doing it because they want to improve the efficiency of their facility, reduce costs, and reduce their heating environmental footprint,” he adds. “Giving them the option to buy the soup-to-nuts maintenance package allows them to control their costs, so they don’t have to get two years into a project and find they had an unplanned breakage and now they have to spend tens of thousands of dollars that was not in their original budget. It allows them to look at a project long-term, remove risks, and enables them to focus on their core business, which is probably not generating electricity and thermal energy.”

The oil and gas industry is “very busy” in utilizing microturbine technology, Crouse notes.

“Beyond that, we’re starting to see resurgence in CHP with food processing, small industrial customers, hotels, some swimming pools, and other applications,” he adds. “We’re seeing a growth in those markets pretty much on a global basis.”

Utility interconnect is typically one of the biggest challenges in microturbine technology, Crouse notes.

“It’s a challenge to try to reduce some of the hurdles or barriers for customers to make decisions to install this kind of technology,” he says. “The power electronics are built to UL [Underwriters Laboratories] standards for utility interconnect similar to what you would find in a solar PV [photovoltaic] system. We try to design to UL or IEEE [Institute of Electrical and Electronics Engineers] standards to make it easier for customers to do that. Utility interconnect is one area where it takes some time and effort to understand it and help them go through the process.”

Photo: Capstone Turbine Corporation Twelve Capstone C65 Hybrid UPS microturbines are installed in Syracuse University’s Green Data Center.

Air permitting is another area on customers’ radar.

“We’ve designed the product to meet California Air Resources Board standards, which are among the most stringent in the world,” says Crouse. “Most of the time, if a product meets the standards for the California Air Resources Board, then it will meet the standards in the local area wherever they may be going.”

Those facility managers interested in starting the process of installing microturbines make contact with a distributor who walks them through the process of gathering information about the facility’s electrical usage and thermal energy uses—whether it’s hot water or chilled water.

“In some applications, we’re actually taking the exhaust and drying or heating the process,” says Crouse. “We get them to share with us their utility bills and gas bills. We have an economic calculator that’s an Excel spreadsheet designed to model the performance of a project and its output—electrically and thermally—based on the site conditions as well as the economic and environmental performance.”

Based on all of the input, a report will detail how many hours a year is an optimal number of hours to run, the sort of thermal production, electrical production, what the return on investment or simple payback may be, as well as the carbon reduction associated with the project due to the efficiency improvement, Crouse says.

Crouse points out that the financial incentives for microturbines aren’t as abundant as those associated with other technologies, such as fuel cells, wind, and solar.

“If there are incentives, we factor that into our evaluation, and it certainly helps if there are,” he says. “The good news is, given the spark spread in several regions of the country, the economic payback is still excellent for our technology.”

Enercon Engineering custom designs and manufactures controls, switchgear, packaging, enclosures, power modules, and cogeneration units for customer-provided engine generator sets. The company also does mechanical packaging of genset and cogeneration units, including comprehensive testing for engine-generator sets with or without switchgear, either diesel or natural gas fueled.

Several years ago, Enercon was involved in the packaging of a PureComfort 360M+2 cogeneration system for East Hartford High School in Connecticut. The PureComfort system is a natural gas-driven combined cooling, heat, and power (CCHP) solution based on microturbines. It generates electricity onsite while simultaneously recovering exhaust energy to provide space cooling.

United Technologies Corporation (UTC) had mated a Carrier chiller with a Capstone microturbine, says Mike Martin, who handles engineering sales for the company. The cogeneration package included four 60-kW, continuous-run microturbines. The cogeneration system provides electric power, hot water for heating, and absorption chilling for school air-conditioning.

“We engineered a skid-mounted modular concept,” says Martin, contract and proposal manager of Enercon Engineering. “We took the four microturbines and mounted them on modular, shippable steel skids. Internal to the skids were the high-voltage and low-voltage cabling and the high-pressure and low-pressure gas line.

“We preassembled the exhaust duct work into the chiller, so we completely assembled and tested the product, put it on trucks, and shipped it to the site,” he continues. “They took it off the truck and put it on the pad with minor reassembly. It took them four hours to test the whole unit to get it up and running. Their commissioning was weeks sooner than normal.”

The CHP system has a 240-kW power output, an absorption chiller output of 120 RT, 1,100 MBH hot water heating, and backup power capabilities. The package also included a 5-kVA 480/240-V AC step-down transformer, an 800A distribution switchboard with eight 125A circuit breakers, eight 125A NEMA, three non-fusible disconnect switches, and pre-piped power/control conduits.

Martin says in previous projects, UTC had local contractors mount and install the microturbines and chillers.

“That made the installation time longer because they had to assemble it onsite, and if it happened to be in inclement weather, it took longer,” says Martin. “At times, the union trades would be a little bit more expensive for onsite work, and then they had to completely inspect and test the system after it was over.”

Enercon did several subsequent projects for UTC before Carrier took over the PureComfort product. The company also has worked with Capstone.

“The units we did for East Hartford High School were 60 kilowatts each,” says Martin. “There were four of those. Capstone improved the efficiency and rebranded those 65 kilowatts, and we used that for multiple other projects. About two years ago, Capstone reconfigured their product and improved their efficiency, turning it into a 200-kilowatt microturbine.

End-users embrace the technology because it’s green, Martin points out. “Capstone likes to laugh and say if they install one in California, the exhaust coming out is cleaner than the air going in.”

Data centers continue to be the largest market for the technology, he adds. “They want reliable power that’s not contingent upon the electrical grid. As long as there’s a natural gas supply, they need no other outside electrical stimulation; they’re self-sustaining.”

Microturbines have a favorable maintenance record, Martin says. “One year of prime power is about 8,000 hours,” he says. “What we’ve heard about the C200 is I think somewhere around 20,000 hours you need injector maintenance, and somewhere around 40,000 of continuous use you need to remanufacture the recuperator.

“That’s a long time,” he continues. “Realistically, you’re looking at three years of continued non-stop operation before you have to perform any maintenance other than an air cleaner or air filter, something minor.”

The unique footprint is always a challenge, says Martin.

“Every site has limits on height and width,” he says. “We did a project for UTC with 16 microturbines. We had to break them into two different groups of eight to run into two different chillers and the footprint on the setback area was on the 15th floor. We had some challenges with the available space.”

Additionally, there also are always permit issues, particularly in areas of the country where only certain amounts of emissions are allowed, Martin adds.

Most of the financial incentives for installing microturbines are in the northeastern states, Martin says. “They’ve made it much more economical to install a microturbine, because, dollar for dollar, a microturbine is more expensive than a conventional reciprocating engine,” he says.

Enercon also packages for other turbine manufacturers, such as those who make conventional gas turbines. The company builds power modules, a modified ISO shipping container with a diesel or natural gas engine inside.

“It’s a complete turnkey power plant on a chassis,” says Martin. “You could just back a truck up to it, pull it to a site, fill it with fuel, make your electrical connection, and start it and run it.”

Alturdyne has packaged gas turbine systems for the commercial and government sector since 1971. The majority of the company’s business is in custom reciprocating engine power systems from 10 to 5,000 hp. The company also is active in the development and application of engine natural gas-driven chillers and cogeneration units for distributed utility applications.

The company packages gas turbine, rotary, and reciprocating engines for applications including generator sets, compressors, hydraulic start systems, high-speed reduction drives, ground power units, and air-transportable power systems, as well as selected components of high-speed turbo machinery.

Alturdyne president Frank Verbeke is seeing an increased market for the technology.

“You can make a turbine engine perform with regard to emissions control and do things that you can’t make the reciprocating engines or rotary engines approach,” he says. “Each engine has its own salient features, but turbine is unique in that it will burn all different types of fuels. We’re working on burning of landfill gas with an associated company and looking for other ways to consume distillate fuels with a low-emissions signature.”

Photo: Enercon Engineering Enercon Engineering custom designs and manufactures controls, switchgear, packaging, enclosures, power modules, and cogeneration units for customerprovided engine generator sets.

Photo: Enercon Engineering

While aerodynamics is well understood, as well as acoustics, “combustion of various fuels still remains a big unknown in a lot of areas,” says Verbeke.

Looking to the future, he adds: “we’re trying to make zero emissions engines.”

“It’s possible to do that, but it costs money for research and development, and it costs a little bit more money when you put the final product together,” he says. “We’re a small company, so we’re competing for the same dollars that are available for research and development with the large companies; that makes it very difficult for us to do that.”

NVision is a company that manufactures three-dimensional digitizing scanners, software, and contract services for reverse engineering, inspection, and rapid prototyping for turbines as well as other applications.

“We help people remanufacture new turbines from old turbines as well as associated equipment,” notes Steve Kersen, vice president of sales and marketing for NVision. “Many times, we’ve worked with nuclear power plants and general power plants that are old and need to update the plant.

“It’s not only just turbines; sometimes they have analog systems they’re moving to digital, and they want to fit new equipment with the old equipment at an existing plant,” he adds. “We can precisely measure where the old equipment is going to be updated with new equipment so they can remanufacture new equipment that will work the first time they put it into service. In the old days, there were tape measures and height gauges, and it doesn’t work so well.”

The second type of work NVision does on turbines is high-speed inspection. “They make a new turbine, and we can inspect it very quickly with this equipment,” adds Kersen.

The market for turbine technology is increasing after a two-year recession lull in response to the world’s need for more power, he notes.

“Everyone is putting in new equipment in older power plants to make it more efficient and put out more energy,” says Kersen. “They’re not building power plants quick enough.”

In many power plant refurbishments, drawings don’t exist or cannot be “trusted,” he says.

“You’ve got to start from some point and that is where the three-dimensional reverse engineering comes in,” he says. “It can perfectly dimensionalize the equipment so they can remanufacture it.”

The remanufactured turbine equipment is produced at a higher quality, with new technology allowing for more efficient turbine blades to be made and to turn out more power, Kersen says.

Collin Ellis, engineering manager at NVision, adds that such programs as Computational Fluid Dynamics helps make the system more efficient and enables reverse engineering to take place onsite to make the parts fit the first time.

One company that has utilized NVision technology is Power Systems Manufacturing, a wholly owned subsidiary of Alstom. The company provides high technology and aftermarket parts and services to the large-frame industrial gas turbine business, primarily power generators and large F-class gas turbines, the predominant technology for combined cycle gas turbines in the industry. The company also offers field services, repair, and research and development. The company provides retrofit kits that not only renew turbines but also reduce emissions to the lowest possible levels.

Typical clients are utility companies or large power users that run gas turbines to generate electrical power. The company’s products include high-performance turbine airfoils, dry low nitrogen oxide (NO_x) combustion systems, fuel nozzles, and vanes, and complete upgrade kits to convert ABB, Siemens/Westinghouse, and General Electric non-low NO_x or factory-installed low NO_x systems to low emission systems capable of both gas and liquid operation.

Power Systems Manufacturing has relied on NVision technology for 10 years in utilizing its three-dimensional laser scan technology to analyze, model, and redesign parts for substantially higher performance than the original parts to enhance the performance of each particular turbine in which they are installed.

“If we are looking to reengineer a component for an original equipment manufacturer gas turbine, we would use NVision’s laser scanner in our metrology lab,” says Jeff Benoit, vice president of business development for Power Systems Manufacturing.

The company utilizes the scanning geometry into a computer-aided design (CAD) program to begin to create the basic definition of a solid model for a retrofit kit. The scanning also enables Power Systems Manufacturing to quickly identify any issues associated with the manufacturing of its first article castings.

“With a full design model of the hot section of the turbine, we then design parts that integrate with the complete system,” says Joe Hackett, Metrology Manager for Power Systems Manufacturing. “Fully characterizing the existing system is the first step to improving it, and the HandHeld laser scanner makes a significant contribution to our ability to obtain substantial reductions in emissions.”

Photo: NVision Laser scanning can provide retrofitters with a more accurate model, more quickly than with a CMM.

“It’s very visual,” says Benoit of NVision’s technology. “You’re able to see it right away as opposed to something like a Coordinate Measuring Machine (CMM), which is very point specific and a little bit more accurate, but much slower. NVision helps from a productivity standpoint in the type of design we use.”

The laser scanner captures tens of millions of points per hour, making it possible to characterize the complete surface to 0.005 inch or less.

Previously, Power Systems Manufacturing had typically used a CMM to measure as many points as possible during the week.

“The problem with this approach was that a CMM measures one point at a time, but to accurately model the geometry of a complex 3D [three-dimensional] contour such as is found on a turbine blade, for instance, you need millions of points, sometimes many millions, to get the geometry exactly right,” says Hackett. “Generating this number of points with a CMM would take months, while the most that can be captured in a week is probably somewhere in the tens of thousands.

Photo: NVision Until Power Systems Manufacturing started using NVision’s HandHeld, the company had outsourcedpoint cloud data gathering.

Photo: NVision To record the shape of a turbine component, the technician holds the laser sensor so that a line of laser light appears on the body. As he moves the sensor over the surface of the mold, the part is rendered real time and gives him immediate feedback.

“We were able to intelligently select those points in order to capture the most critical areas,” he continues. “But we were often left approximating contours and could never be totally sure that we weren’t missing important points.”

Until Power Systems Manufacturing started using NVision’s HandHeld, the company had outsourced point cloud data gathering.

The HandHeld systems projects a line of laser light onto the object while a small charge-coupled device (CCD) camera views the line as it appears on the surface. A dedicated PCI interface card translates the video image of the line into more than 768 3D coordinates, allowing for a maximum data capture rate of 23,000 points per second.

Using the HandHeld to record the shape of a turbine component, a technician holds the laser sensor so that a line of laser light appears on the body. As the technician moves the sensor over the surface of the mold, the part is rendered real time and gives immediate feedback to the technician, who sees missed areas and fills them in with another pass. The system combines the coordinate data with Cartesian and angular coordinates generated at each position of the mechanical arm, resulting in a dense cloud of 3D data describing the object’s surface. Upon completion of the scanning, the point cloud data is post-processed into a surface model of the component. Inspection software compares the original design geometry to the actual produced part. The complete surface of the actual part is analyzed and a color map is generated showing the error or difference between the two data sets.

Benoit concurs with others that although the market for turbine technology took a hit in 2008 with a reduced demand for electricity, driving a pull-back in his company’s customers’ capital spending—as well as spending on repairs and field services—there has been a reappearance of companies needing to spend money on repairs and field service.

Turbine Resources Unlimited provides turbine overhauls, component repairs, and coating options to extend the life of a turbine. Most of the turbines the company services are large heavy frame engines. The company repairs components, fuel nozzles, turbine blades, buckets, combustion liners, and transition pieces.

“What I hear from our customers is they’re pretty much trying to maintain their fleet,” says William Howard, president of Turbine Resources Unlimited. “The economics behind that is it’s a struggling economy, and they are trying to keep their units available and within the EPA requirements on the least amount of money possible. Where we are able to repair parts as opposed to them having to buy new parts, that is a favorable option for them.”

Howard notes that over the past decade, the industry has seen a number of improvements with the internal cooling of gas turbine components, thermal barrier coatings, and other new technologies that have allowed the increase in firing temperatures, improving the turbine efficiency and reducing the number of pollutants as the firing temperatures increase. The geometry of newer turbines is also helping, Howard notes.

Going forward, Howard sees a trend towards smaller units being installed at the point of the load center.

“I see more fuel-efficient technologies stepping in to take up some of the slack,” he adds.

Author's Bio: Carol Brzozowski specializes in topics related to waste management and technology.