'.ARTICLE l MAKALE current market is very bad. Cogeneration has been a victim of weak implementation of policy objectives, partial liberalization of electricity and gas markets, and !he rapid rise in oil prices. THE ENVIRONMENTAL IMPACTS AND SAVINGS FROM COGENERATION Cogeneration offers !he besi use of valuable fossil fuels, combining high efficiency and low emissions, flexibility ta meet specific needs far heat and power, and reducing transmission losses by being situated close ta !he end user. The trend towards decentralized power production will alsa favour !he increasing use of renewable energy and further improvements in energy efficiency at !he point of use. Nowadays, !he major contribution !hat cogeneration can make ta achieve !he Kyoto targets is not disputed by anybody nar is the facı !hat these targets can not be realistically achieved without increasing !he share of cogeneration. Cogeneration optimizes !he energy supply ta all types of consumers with !he following benefits ta both users and society at large: - lncreased efficiency of energy conversion and use - Lower emissions to the environment, in particular of CO2, the main greenhouse gas. - Large cost savings, providing additional compelitive ness far industrial and commercial users, and offering affordable heat far domestic users. - An opportunity ta move towards more decentralized forms of electricity generation, where planı is designed ta meet !he needs of local consumers, providing high efficiency, avoiding transmission losses and increasing flexibility in system use. This will particularly be the case if natural gas is !he energy carrier. - lmproved local and general security of supply local generation, through cogeneration, can reduce the risk that consumers are lef! without supplies of electricity and/or heating. in addition, !he reduced fuel require ments of cogeneration reduce import dependency a key challenge far Europe's energy future. - An opportunity ta increase the diversity of generation planı, and provide competition in generation. Cogeneration provides one of !he mas! important vehi cles far promoting liberalization in energy markets. - lncreased employment- a number of studies have now concluded !hat the development of CHP systems is a generator of jobs. Environmental concerns are becoming more important in governments' agendas, and climate change is undoubtedly one of !he key issues, especially since agreement of mas! governments to achieve the Kyoto targets. it is widely recognized that cogeneration can make a major contribution towards these targets, and many governments are using the development of cogeneration as one of their strategies ta reduce greenhouse gas emissions. The European Commission can fulfil !he vital role of co-ordinator here, ta ensure that the 8% target of emissions reductions by 2008-12 is achieved. The assessment of carbon savings from a cogeneration project is a hotly debated subject, as it is very difficult ta prove what electricity it displaces. This issue has been at the heart of a long-running discussion in European markets, with na agreement. Does the cogeneration scheme displace: - The mix of electricity production in !he country - The most marginal power planı on the system - The next power planı ta be built by the power industry - The besi theoretical power plan! available? Depending on the answer, the savings in carbon dioxide can vary from 100 kg/MWh ta more !han 1000 kg/MWh. The same issue faces ali projects that displace other electricity generation. in addition ta !his, energy efficiency measures and most cogeneration planı are demand-side measures rather than supply side projects. in these cases, the savings are dependent on the operation of energy consumer. This will vary depending on economic activity, product needs, and sa on. Alsa, it is often difficult ta disentangle !he impact of one demand side measure from others. Far example, ifan industrial site install cogeneration, it will assess the energy needs of the site prior ta determining the size of the cogeneration plan! !his process may itselfstimulate other energy saving and thus greenhouse gas reduction is achieved by the cogeneration projeci itself is quite difficult ta assess precisely. The text box gives a calculation of !he environmental benefits of cogeneration. lf Europe achieves the target of 18% of electricity from cogeneration carbon dioxide savings will be around 150 million tones. ENSURING QUALITY TO ACHIEVE ENVIRONMENTAL BENEFITS National situations are sa different that agreeing on a common definition far cogeneration has proven a very difficult task. However, it is necessary ta achieve a system, which ensures that the growth of cogeneration leads ta the reduction of emissions. Systems should lake into consideration the energy mix situation in different countries. The UK quality assurance programme could serve as a good example far programmes in other countries. The programme involves a quality asessment based on a Quality lndex (QI). A suite of definitions is being developed ta cover the whole range of schemes applications, sizes, technologies and fuels, and taking into account !hat regardless of !he electrical efficiency of a projeci a scheme that recovers heat will generally be more efficient than one that does not. The QI methodology is built on the rationale that electricity supplied is more valuable than heat supplied. it compares CHP with separate electricity only and heat-only alternatives. The QI therefore offers scope far a major improvement ever conventional approaches simply based on overall efficiency. The general form far QI calculation is: QI: X X Efficiencypower + Y x Efficiencyheat where: Efficiencypower = annual power supply (MWhe) / annual fuel use (MWh) Efficiencyheat = annual heat supply (MWhth) / annual fuel use (MWh) ECOGENERATION WORLD �
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