Showing papers on "Load shifting published in 2005"

Routes to energy efficiency: complementary energy service products in the UK residential sector

Abstract: Energy service companies represent a potential vehicle for transformation of the way the UK residential energy market operates and a windfall gain in supply-side energy efficiency. We consider two potential energy services company products that can provide economic and/or environmental benefits; grid-connected micro-Combined Heat and Power (CHP) and a time-of-use electricity tariff. We analyse each product independently, and then consider the synergies that exist between them. We draw upon a residential electricity demand model based on behavioural patterns which allows “shiftable” load to be identified, and assume that a consumer will shift load from high-priced periods to lower-priced ones. The economics of a time-of-use tariff as an independent product are thus evaluated. A cost minimisation model that chooses the best operating strategy and optimum microCHP electrical generation capacity to meet energy demand for the consumer is then applied to energy demand cases with and without load shifting under the time-of-use tariff. It is found that time-of-use charging and micro-CHP are weak complementary measures in an economic and environmental sense because load shifting results in only a slightly higher portion of the electricity load being met by the more efficient micro-CHP unit, resulting in a small decrease in equivalent annual cost and a small greenhouse gas emission reduction over and above that of each product independently. Both the time-of-use tariff and micro-CHP products are independently effective, offering a positive economic outcome to the investor. The synergy between the two products is small, but comes at no additional capital cost, and is therefore welcome.

Short term hydrothermal coordination in the presence of price-responsive loads

Abstract: This paper is concerned with the representation of price-responsive loads in the short term coordination of predominantly hydroelectric hydrothermal systems. The proposed approach allows the representation of cross- relationships between demand and price during different dispatch intervals of a given time horizon. Also, consumer energy constraints which behave as dynamic restrictions can be taken into account. By that means, a load shifting program in which the consumers' overall energy consumption remains constant throughout the time horizon can be simulated. The short term hydrothermal coordination is solved as a single optimization problem employing the primal-dual interior point method. A 32- bus equivalent system of the Southern Brazil Interconnected Power System is used to illustrate the effect of price-responsive loads on reservoir storages.