COGENERATION CAN STABILIZE POWER COSTS LONG TERM
by Victor Neuman
In a recent speech to the San Francisco Chamber of Commerce, Michael Kahn, esq. chairman, Board of Governors, California Independent System Operator (Cal-ISO), told California Business owners that they had to get use to rolling blackouts.
However, in addition to power reliability problems, there have been large increases in electrical costs. Californians paid $7 billion for electricity in 1999, $27 billion in 2000 and an estimated $50 billion in 2001. Kahn used the analogy that if electricity were gasoline, it would have been priced at $1.50 in 1999, $6 in 2000 and $10.50 in 2001.
California annual electrical costs
Silicon Valley is particularly challenged because of limited electrical generating capability and transmission lines that have reached their maximum capabilities. This problem of the transmission line link is referred to as Path 15 and is currently being upgraded by Pacific Gas & Electric but it will take some time before relief is in sight.
 A Titan 130 gas turbine generator set by Solar Turbines Inc. |
In December 2000, Michelle Montague-Bruno of the Silicon Valley Manufacturing Group (SVMG) told TechWeb, “If you lose power for an hour, it doesn't mean you are just shut down for an hour. You send employees home; you have to recalibrate… a transformer could blow, and you could be out for days.” SVMG said that the blackouts a year ago cost some member companies anywhere from $1 million per minute to $1 million per hour. The San Francisco Chronicle quotes Thane Kreiner of Affymetrix, a biotech firm, as saying that $125,000 in lost production was the result of two blackouts in May 2001. As a result, the company has purchased a $1.5-million backup generator for another of its sites.
 An 85mW cogeneration plant in Boffalora, Italy, based on a GE 6FA gas turbine. |
So far, cleanroom owners are not planning to pack their bags and move to locations that offer cheaper, more reliable energy. Which is one reason why cleanroom operators are being forced to fall back on engineering solutions to cope with rolling blackouts and higher electrical prices.
Diesel generators
Most cleanroom owners are familiar with the use of diesel generators for emergency back-up. These generators need to be coupled with an uninterruptible power source so that the electrical load has some means to ride-through the 6-10 seconds until the generators reach full power. Batteries and flywheels are the two current systems for providing this ride-through capability.
Until recently, most backup generators were not tested in a real blackout. Not surprisingly, some untested systems fail, at least momentarily, to provide continuous power during a blackout. According to Tom Dinkel of the Energy Group of Cupertino Electric, any FDA-certified facilities might find their certification called into question if a momentary blackout caused their cleanrooms, fume hoods or other ventilation devices to lose either positive or negative pressure. Also, production facilities might have to discard whole batches in manufacturing, while facilities in clinical trials might be required to re-due entire research projects because of a blackout induced interruption in contamination control.
Cogenerating power
Another increasingly attractive possibility is to cogenerate and produce heat and power on the same site as the cleanrooms.
Advantages:
- Reliability of power can be increased.
- Possibility of lower electrical rates in the long term.
- Stable power costs long term.
Because electrical rates in California are likely to remain uncertain for the next five years, there is a degree of uncertainty in any economic analysis of cogeneration. By entering into a 10-year or 20-year cogeneration project, electrical prices for that building or group of buildings will not be an uncertainty. However, the only risk is that greater savings might have been achieved without cogeneration, but only if electrical prices decrease in the future.
In large multi-megawatt cogeneration systems, the preferred equipment for large systems with continuous operation is a natural-gas-fired gas turbine. This system would probably be a combined cycle that recovers waste heat to steam to power a steam-turbine-driven electrical generator. According to federal regulation, 5 percent of the steam would be used for process, heating or cooling requirements. The other requirement is that the plant heat rate must be a minimum of 37.5 percent when 5 percent of the energy is used in other ways than to generate electricity. For smaller systems and those used for peak shaving and non-continuous use, a natural gas reciprocating engine is used.
Jeff Bush of Sempra Energy Solutions indicates that his company has several cleanroom projects in the works with minimum power generation sizes in the 2-3 megawatt range.
Victor Neuman is a principal with the San Francisco office of Alfa Tech Inc. Alfa Tech specializes in designing cleanrooms for semiconductor/electronic clients as well as pharmaceutical production. Alfa Tech is the largest mechanical-electrical-process engineer headquartered in Northern California with offices in Asia.
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Large cogeneration example, multiple megawatt size
In the following example, a proposed large cogeneration plant shows a positive cash flow in less than five years with the initial investment guaranteeing stable electrical rates.
The cost model includes the cost of a new transmission substation but excludes the land acquisition costs. Soft costs for design and permitting will be included. To be conservative, it will be assumed that no excess power is sold back to the utility company.
Smallest cogeneration size, 30-60 kilowatt
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On the other end of the scale are the small cogeneration systems. The newest entry in this category is the microturbine. Some of the available sizes include models at both 30 kW and 60 kW. The microturbines were designed to be low in maintenance but only have several years of operating history. One example is the Capstone microturbine installed for Harbec Plastics. This New York company was effected by blackouts and decided to go to cogeneration for its primary power source. Harbec was looking for extremely low emissions, which would then simplify its air pollution permitting and reflects its commitment to be a good corporate citizen. The resulting system as installed produced power, heating, hot water and chilled water. With a long-term gas contract for $6.85/MCF, the resulting cost of power was $0.75/kwh compared to $0.10/kwh for power purchased off the grid. The dollar value of the recovered heat for heating and cooling was an important part of this equation. In Northern California, the 30-kW model is currently exempt from air pollution permitting because of its small size. This is true even if multiple units are installed.
What to do if you are considering cogeneration?
For cleanroom owners considering cogeneration, there are several steps in the process. First is a feasibility study by an independent consulting firm to establish the electrical load profile and other unique characteristics of each site. If the economics look favorable at this stage, then a more detailed design study should be undertaken. After the feasibility study and either before or after the design study, request-for-proposals should be generated to cogeneration developers. The list of interested developers varies depending on the size of the prospective power plant. The list of questions to be considered includes the following:
- Definition of annual electrical use and load profile
- Chilled water system design and distribution
- Power plant layout and space requirements
- Air pollution and other environmental permit requirements
- Review of electrical utility transmission lines and intertie requirements
- Detailed cost estimates
- Detailed power plant design
- Review of legal issues for ownership, sale and distribution of power
There are numerous cogeneration plants that have been in operation since the last energy crisis in the late 1970s and early 1980s. Those owners reaped the benefits of their decision at that time. Now may be the time for current cleanroom owners to consider cogeneration as the solution to their current problems of electrical grid unreliability and rising electrical costs.—VN
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Resulting average cost per kilowatt-hour
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The hypothetical example shows a positive cash flow at the end of Year 4. Firm natural gas contracts with fixed prices for 20 years can be arranged. Predicting the utility rates for the cogeneration plant to be compared to is the biggest variable. In this example, the rates are escalated 20 percent for each of the first 3 years and 2 percent thereafter.