Combined Operational Planning of Natural Gas and Electric Power Systems: State of the Art

Abstract

The growing installation and utilization of natural gas fired power plants (NGFPPs) over the last two decades has lead to increasing interactions between electricity and natural gas (NG) sectors. From 1990 to 2005, the worldwide share of NGFPPs in the power generation mix has almost doubled, from around 10% to nearly 19%; reaching in 2007, for instance, the 54% in Argentina, the 42% in Italy, the 40% in USA, and the 32% in UK (IEA, 2007; IEA, 2009a). The installation of NGFPPs has been driven by technical, economic and environmental reasons. The high thermal efficiency of combined-cycle gas turbine (CCGT) power plants and combined heat and power (CHP) units, their relatively low investment costs, short construction lead time and the prevailing low natural gas prices until 2004 have made NGFPPs more attractive than traditional coal, oil and nuclear power plants, particularly in liberalized electricity markets. Additionally, burning NG has a smaller environmental footprint and a lower carbon emission rate than any other fossil fuel. NGFPPs are the link between electric power and NG systems, since they play the role of producers for the former and consumers for the latter. Therefore, the growing use of NGFPPs has had a great impact on the NG market. Power generation accounted for around half of growth in gas use from 1990 to 2004; over the most recent five years, this proportion rose to nearly 80% (IEA, 2007). This fact is especially notable in those countries where large capacities of NGFPPs have been installed. Two major indexes indicate the level of interrelations between electric power and NG systems. The first one is NG demand for power generation as a share of the total NG consumption, and the second one is the share of electrical energy produced by NGFPPs. Both shares depend not only on the NGFPPs installed capacity, but also on relative fuel prices (NG, coal, oil derivatives products) and the availability of other energy resources (hydroelectricity, wind power). Fig.1 shows year 2007 indexes for several countries and also on a global basis (IEA, 2009a, b). Significant values of both indexes are typically a sign of strong interdependencies. Fig. 1 includes some of the countries with the highest indexes in the world, such as Argentina, Italy, Malaysia, the Netherlands, Russia and Turkey. The interdependencies between electric power and NG systems can be described from a technical-operational viewpoint. The NGFPPs dispatch determines the total amount of NG 12