Consulting-Specifying Engineer - July 2008 - (Page 14)

M/E Roundtable reducing pollution by using wind-generated electricity in place of burning hydrocarbons have a major conflict with the environmentalists who believe that wind turbines kill too much wildlife. For those of you who have seen how fast the wind turbine blades turn, it appears that the only birds and bats that are killed by the turbine blades are those eliminated by Charles Darwin’s ”survival of the fittest.” Any bird or bat that flies so slow as to be killed by the slow revolution of the wind turbine blades undoubtedly would be killed by any one of a plethora of other dangers like flying into a tree or mountainside. The most promising alternative fuel has to be methane recovered from waste decomposition. Technologies using recovered methane from a waste stream have been in use for at least 50 years in sewage treatment plants, and the same technologies could be used in the recovery of other flared fuel sources with little modification. FLICKINGER: The two promising technologies are wind and fuel cells. Though wind turbines have been in use for a while, efficiencies in propeller design have lowered the minimum wind speed necessary for power production. The lower maintained wind speed requirement increases the number of new sites available for wind applications. If a locale’s wind map indicates adequate/continuous wind, then wind turbines in the 50- to 400-kW range can prove economically practical. Further, in a few states, it would appear that with financial incentives, phosphoric acid fuel cells can be economically viable. Manufacturers have recently increased fuel cell stack capacities from 200 to 400 kW, while maintaining essentially the same physical dimensions. Additionally, by incorporating tri-gen applications, their overall thermal efficiency approaches 92%. Though fuel cells are not completely sustainable, their carbon footprint is significantly less than traditional distributed power sources due to their efficiencies and recombinant process of their combustion byproducts, with the main byproduct being water. CSE: Describe some recent on-site power designs you are familiar with, and how the design team used innovative approaches. LOVORN: A local, solid waste management firm had several capped landfill sites that were producing decomposition methane that was being flared. The firm received a grant from the Federal Energy Regulatory Commission (FERC) to install a small, waste gas engine generator to recover the flared methane and use the generated electricity in operating their site facilities, which included offices, lechate treatment, truck maintenance garages, and other ancillary buildings. It was the Ask the experts: renewable energy power Every month, Consulting-Specifying Engineer editors ask a distinguished panel of experts for information about how to best solve your problems, challenges, and new engineering issues at www.csemag.com/asktheexperts. Below is a question for July’s topic, specifically about renewable energy power. to electricity at an efficiency of 9% to 12%. IBM is using thin film cell technology, which combines copper, indium, gallium, and selenide to yield about 15% electricity from the incident sunlight. Both of these technologies are poised for substantial growth in the immediate future, primarily due to current fuel prices. The second part of the reader’s question is significantly more complicated. The first place to start is to determine the facility’s overall load factor. A load factor of 65% or greater is good. For commercial spaces and schools, which typically have poor load factors (less than 40%), the most immediate solution is daylight harvesting. Not only does this reduce the electrical lighting load but also the HVAC requirements for cooling the associated space. One can also enlist the help of consultants to do an energy audit of the facility. One strategy for limiting peak demand might include the rescheduling of energyintensive manufacturing processes to stagger production schedules and nonpeak periods. There is no simple way to economically minimize on-peak demand short of simply turning things off. “ Out here in northern California, the next level of state rebates is just for fuel cell or wind generation. Solar is no longer to receive the level of state subsidy used for the last two years. Are renewable energy sources going to be costeffective, with dwindling state support and few federal tax credits available? What technique should plant managers, and users of large chunks of power, use to minimize their peak demands of electrical (or other) power?” —John Turner, Electrical Engineer, CD Engineers, Fairfield, Calif. THOMAS FLICKINGER: The reader’s observations are interesting. Intel is building new manufacturing plants that will use silicon-based technology, which can convert usable light 14 Consulting-Specifying Engineer • JULY 2008 http://www.csemag.com/asktheexperts

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - July 2008

Consulting-Specifying Engineer - July 2008 Contents Viewpoint Letters News M/E Roundtable 40 Under 40 Using Demand-Based Reset Strategies VFDs and Motors: Making the Right Match Grounding and Bonding Practices for Hazardous Areas Codes & Standards Case Study New Products Equipment Lifecycles Advertiser Index Green Space

Consulting-Specifying Engineer - July 2008

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