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ElectricityIn most countries, electricity supply is a major source of atmospheric pollutants that degrade air quality, cause acidification and global warming. It also causes other impacts including nuclear and solid wastes, water consumption and loss of visual amenity. In general, regulation is reducing the emissions of most toxic and acidic pollutants, but not carbon dioxide and other greenhouse gas emissions to the same degree. Switching to natural gas and renewables may reduce growth in emissions, but continued demand growth may overwhelm the benefits of fuel switching. As with other sectors, energy efficiency and demand management are key options. SENCO has worked extensively on the modelling of electricity demand and supply. This modelling includes technologies, system operation, emissions, and costs. A special expertise concerns the modelling of electricity demand. SENCO 's model of electricity services is called EleServe. It simulates electricity demand and supply flows on an hourly basis over a number of scenario years and may be used to develop least cost electricity systems with low environmental impacts. See the Trade and Energy-Space-Time pages for models which also address spatial and trade aspects, and SEEScen for contextual energy scenarios. A video of EleServe optimising diurnal electricity service supply can be downloaded here (1 Mb, wmv) or here (0.2 Mb, gif). It shows the simulation of a hypothetical system for a winter's and summer's day for 2025 with high levels of energy efficiency and substantial components of renewables and CHP (called Essential generation). The simulation shows how highly variable inputs might be absorbed with the help of load management and storage. It demonstrates how important load management - shifting heat loads with end use storage - might be in the integration of renewable and CHP electricity. In this case, the net load met by Optional thermal generators is almost totally flattened even without the use of system storage such as pumped storage. EleServe consists of a demand module and a supply module. The model operates on sample days in a year of a scenario. The sample output below is for two sample days: winter and summer. The demand module of EleServe calculates stock turnovers of end use equipment, electricity consumption and capital investment for 35 end uses and appliances across the domestic, industrial and commercial sectors. Each demand varies with socioeconomic activity and some demands (heating, lighting, cooling) also vary with the weather. The chart shows demands without additional load management.
Demands for heat and cooling may be shifted in time using storage such as hot water tanks, in order to reduce the variation in demand that has to be met by thermal power stations. This results in lower capacity requirements, the better integration of variable sources such as renewables and CHP. The chart shows demands with additional load management..
The supply module first calculates the outputs from non-optional electricity sources - CHP and renewables. These are highly variable and not well correlated with demand. The chart shows illustrative outputs. The supply module then adjusts system storage (e.g. pumped storage) and trade, and operates power stations in an order that minimises costs. Reserve requirements, part loading characteristics and start-up time and costs are accounted for. The capital and running costs, and atmospheric emissions for each power station are calculated. The chart shows the output from aggregated power stations for the UK.
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