Journal of Energy Engineering

Most cooling reservoirs in the U.S. employ a surface intake, but many could obtain improved performance (decreased intake temperature during summer) by using a submerged intake. Potential improvements were studied using mathematical hydrothermal modeling applied to five hypothetical reservoirs located in Augusta, Ga. For the base case reservoir—characterized by an average depth of 30 ft (9.1 m), surface area of 2,000 acres (809 ha), and areal loading of 0.99 MWt/acre—and a range of vertical mixing parameters, intake temperatures from Apr.–Oct. decreased by an average of 0.7–1.2 °F (0.4–0.7 °C) using a submerged intake as compared with a surface intake. For a range of assumed turbine performance curves and cost parameters, these temperatures yield estimated energy savings of 1,200,000–20,400,000 kWh annually and total, present valued, cost savings of $700,000–$11,600,000. Savings increase as the reservoir area and depth increase and vertical mixing decreases. In most cases, performance also improves with combined use of a surface and a submerged intake, with the former used during initial periods of the annual stratification cycle.

It is well known that the inertia of the water in the penstock is the main unstabilizing factor for the stability of a hydropower plant. Most of the analytical studies on this subject use the lumped‐system approach to include the water‐hammer effects. However, the elasticity of the pipe walls and the compressibility of the water column could have in many cases significant detrimental influence on the governing characteristics of a plant. An analytical criterion for the stability of a single, isolated hydro‐unit is derived including the effects of elastic water hammer. It is concluded that for a system having Allievi parameter (p) less than one, the elastic effect of the conduit should be taken into consideration.

A novel implementation of “manufacturing” thermal and electrical demand to match power plant design in the context of an industrial park is studied. The novelty of the “energy park” concept introduces several areas requiring detailed consideration. Three of these—manufacturing load profile through tenant identification, power plant design and energy costs, and pricing—are addressed. A computer model which calculated economic and thermomechanical performance is utilized. A specific site in southeastern Massachusetts is used as the study's focus. The consumers used are a paper mill, a food processor, and a local hospital. The regenerative Rankine cycle power plant is designed to meet a maximum steam demand of $13\mathrm{kg}/s({10}^5\mathrm{lbm}/\mathrm{hr})$ at all times and electrical demand [3,000 kWe peak] most of the time. An economic analysis driven by derived aggregate energy demand is performed. Both daily and monthly demand fluctuations are considered. This analysis is accomplished using PC‐based spreadsheet software. The total average cost of energy (1982 dollars), assuming electrical and thermal energy are priced equally, is $0.0116/MJ ($12.19/BTU). Pricing strategies to reduce cost and shift demand profile are considered.