ARTICLE / MAKALE Newly sophisticated equipment is much more susceptible to the power surges, swells and transients withinelectricity grids Second, power reliability is becoming even more critical for corporations in this digital age due to reliance on the internet, wireless fidelity (wifi) or other localized wireless networks. There is also the issue of power outages, which are becoming more frequent and of longer duration due to ageing electricity grids (primarily at the distribution level), more intense weather patterns, and stresses on loca! electricity grids and natura! gas pipelines as shifts of load and energy intensity occur around changing loca! development patterns. Even short power outages can drive profitable years into 'the red' by shutting down communications, refrigeration, İnternet sales, retail sales (use of credit card, fax and electronic cash register sales), water and process pumping, as well as air-conditioning or heat in key months. Ali have economic repercussions that, if calculated, aggregated and attributed, make a very strong business case for some kind of long-duration back-up power supply. As one chief executive ofa global microchip firm commented: 'My loca! utility telis me they only had 20 minutes of outages all year. 1 remind them that these four 5-minute episodes interrupted my process, shut down and burnt out some of my controls, idled my work force. 1 had to cali in my control service firm, cali in my computer repair firm, direct my employees to 'test' the system. They cost me eight days and millions of dollars.' Uninterruptible power supply (UPS) units have been around a long time - but they have limited power duration and do not always work as prescribed. Diesel and propane generators and battery banks are the most commonly used units, but are totally reliant on the fuel available or on the condition and limits of the batteries. These remain good short-term options, but not very good long-term options, having high operational and maintenance costs. Many renewable distributed generation options can serve not only asa back-up power function, but also produce power on a daily basis to lower the energy use profile of the business. Such constant use enables the business owner to assess the system's performance, so ensuring reliability in back-up mode. Compared with commercial and industrial consumers, most residential customers are not as exposed to such differentiations of electric and natural gas rates. As a resul!, the third market driver for on-site or distributed energy is the lowering of these rates - once the demand profile of the overall business has been reduced by energy efficiency measures such as re-lighting, installing more efficient motors and heating, ventilation and air conditioning (HVAC) equipment and 'smart' controls. But even after lowering overali energy demand, many commercial businesses stili face higher peak power rates which are sometimes 'ratcheted' - meaning the customer continues to pay a much higher rate for sometime thereafter. Demand charges, similar to celiular rate schemes, are also used universaliy by both natural gas and electric utilities. Distributed power - primarily renewable energy and waste heat or cogeneration - can be used to offset these peak charges. Finally, green power or green consumer markets are attractive options for those businesses needing to comply with environmental legislation on, for example, air emissions or climate change, or who want to demonstrate their environmental credentials publicly as a way of enhancing their corporate reputation and raising the profile of their brand. COMMERCIAL-SCALE PROJECTS EMERGE This article focuses on installations that demonstrate a market trend and that are either fully economic or on the verge of being so. Bigger is not necessarily betler with this kind of projects, so symbolic government demonstration projects do not feature here. 'Beyond-the-grid' markets have two basic themes for industrial and commercial users. üne asset of distributed generation is that it saves time and money on underground or overhead wiring, as well as avoiding the need for step-down transformers. Renewable distributed generation options serve more than a back-up power function - they produce power daily For example, a solar-wind hybrid system consisting of six Southwest Windpower AIR wind turbines, located on top of Estralla Mountain west of Phoenix in Arizona, charges a battery bank fora telecommunication repeater system. Most of the paging systems in the Phoenix Valley receive their signal from this system, instalied in the late 1990s. Southwest Windpower has also installed wind systems on offshore platforms located in the Netherlands. Five turbines (wind only) charge large battery banks which are used to power port and starboard light platforms at the entrance to Rotterdam Bay. Waste heat and solar applications lntrinsic 'behind-the-fence' energy systems providing power to actual operations also appear to be a growing trend. Waste heat has been the step-child of distributed energy. Nevada-based company Ormat, a leader in geothermal and recovered heat technology, has adapted its ORC heat engines, used for over 25 years in geothermal applications, for waste heat and solar applications. in April 2004, the company completed construction and final acceptance-testing ofa 4.5 MW waste heat system installed on a turnkey basis at Enterprise Products' L.P. Neptune gas processing plant. This projeci, the first of many similar recovered heat projects expected to come on-line in the next few years, utilizes previously wasted hot exhaust gases from two turbines driving gas recompression units to generale clean electricity with near-zero emissions. Distributed generation saves time and money on underground or overhead wiring, and avoids the need for step-down transformers 1 ENERJi & KOJENERASYON DÜNYASI ♦ -5-2-+-___ .:..__.:..__;_.:.._...:.._---'===========~ "Kojenerasyon: Yüksek Verim, Temiz Çevre, Ene~ide Yeniden Yapılanma"
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