Associated Electric Cooperative Inc. completed construction of the Dell Power Plant in summer 2007, adding another important resource to meet the growing energy needs of rural electric cooperatives.

The Dell Power Plant is a 580-megawatt, natural gas, combined-cycle plant located near Dell, Ark., on about 100 acres.

AECI purchased the partially built Dell Power Plant from TECO Energy Inc. in August 2005 and finished construction in August 2007.

Combined-cycle plants are among the most efficient type of gas plants with very low emissions, and this plant will be among the very lowest emitters of its type.

These combined-cycle units have greater efficiency than simple-cycle combustion turbine units because they employ both a steam turbine and a combustion turbine to power the generators.

Heat-recovery steam generators (HRSGs) are used to capture exhaust heat to power the steam turbine. Exhaust heat enters the HRSG, or boiler, at about 1,110 degrees Fahrenheit and moves through the structure, heating tubes of water to create steam to power the steam turbine, which turns the generator to produce electricity. Afterward, the exhaust is vented from the stack at about 185 degrees.

In contrast, hot exhaust from the gas turbine on a simple-cycle unit is vented to the atmosphere. This heat-recovery system increases the efficiency of the unit to about 58 percent, compared with 33 percent efficiency of a simple-cycle plant.

Although the Dell plant was designed to be a baseload plant, AECI plans to operate the plant for intermediate generation. It will run during high load periods, summer and winter, to provide energy to member cooperatives served by AECI. The plant design has incorporated fast starting and cycling capability to allow AECI to meet changing member and market demands.

This new plant will provide electricity to AECI member systems, which are growing and requiring more energy to serve their customers. AECI only builds new generating units to provide wholesale power to its member systems. If AECI's generating units produce more power than is needed by member systems, AECI sells that energy to bring in revenue that helps keep members' rates low and stable.

AECI’s mission is to provide an economical and reliable power supply to its member systems, and AECI and its member cooperatives are bound by all-requirements contracts. Those contracts require AECI to provide the wholesale power supply needed by member systems, and those member systems are obligated to buy their wholesale power supply only from AECI.