Electric Power Systems Research 57 (2001) 33 – 39 Economic and environmental dispatch of power/CHP production systems Peter Børre Eriksen Fjordejen 1 -11, 7000 Fredericia, Denmark Received 22 November 1999; accepted 14 April 2000 Abstract The paper describes a method for complying with emission quotas for a power producing or CHP producing system in an economically rational and optimal way. The method is based on extended use of a simulation model (SIVAEL) and a pre-processor which optimises the environmental aspects of each system unit. SIVAEL is a unit commitment/load dispatching model, which solves the problem of optimal scheduling of CHP production. On a weekly basis, the scheduling of power producing units, heat producing units and units with-CHP production is laid down. The pre-processor, PRESIVAEL, calculates the environmental parameters of each system unit. When handling the SO 2 quota, for instance the pre-processor optimises the operation of each coal-fired (or oil-fired) unit, including possible deSO x plants. The application of the method is illustrated by examples. © 2001 Elsevier Science S.A. All rights reserved. Keywords: Emission constraint; Load dispatch; Optimisation model; Thermal scheduling; CHP production www.elsevier.com/locate/epsr 1. Introduction Previously, the planning and operation of a power system, or a system with combined heat and power (CHP) production consisted in expanding and operat- ing the system with a view to supplying the necessary power and heat at the most competitive prices, and with an acceptable security of supply. Since then, envi- ronmental aspects have become increasingly important. Gent and Lamont [1] were the first to consider the emission dispatch problem. Their formulation was a straightforward analogy to the economic dispatch prob- lem, except that they minimised NO x emissions rather than costs. Later on, other solutions to the combined objective of handling costs and emissions in the dispatch were proposed. The literature in this field (e.g. [2–5]) demon- strates that much effort has been assigned to solve the problem. Many variants of algorithms of environmental-eco- nomic dispatch of electric power systems have been developed. The algorithms most often aim at reducing atmospheric emissions (e.g. NO x , and SO 2 ) by including emissions either as a constraint or as a weighted func- tion in the objective of the overall dispatching problem. Since the mid-1980s, quota constraints have been set on the annual emissions of SO 2 and NO x , from the Danish power industry. In 1992, these constraints were supplemented with a CO 2 quota, requiring the Danish power stations to contribute to reducing the Danish CO 2 emission by 20% by the year 2005 compared with 1990. Facing this environmental challenge, the former Danish electricity utility Elsam 1 developed a new method for complying with the emission quotas in an economically rational and optimal way. The method is based on extended use of a simulation model named SIVAEL, and a pre-processor which opti- mises the environmental parameters of each system unit. – The method has the following special characteristics: The method considers combined heat and power production (CHP). Therefore, the method is not re- stricted to pure power production systems. 1 On January 1, 1998, Elsam was divided into two companies, Eltra and Elsam. Eltra is the independent transmission system operator in the western part of Denmark and bears the responsibility for trans- mission and supply. Elsam is now a commercial company serving as a cooperative body for the six largest power producers in Denmark. 0378-7796/01/$ - see front matter © 2001 Elsevier Science S.A. All rights reserved. PII: S0378-7796(00)00116-4