Overview of ENERGY STRATEGY from PLANT OPERATIONS

The department responsible for operating and maintaining the facilities and grounds across Vanderbilt's 330 acres is Plant Operations. In the mid-1980's this department formalized a comprehensive energy strategy for Vanderbilt University. This document is a brief summary of the principle features of that strategy.

DATA: Plant Operations maintains a database to track information concerning the institution's energy consumption, including cost per unit, cost per million BTU's, and total costs. The acquisition and recording of historical energy use and cost are necessary in order to analyze use patterns and comparative cost. Accurate and reliable metering of energy use is also a requirement. A historical data base was created referencing 1980 as the base year for comparison. All forms of purchased utilities are included in this document. In addition, since 1985 a comprehensive electrical and steam metering system has been installed. Internal programs were developed for electricity, water and natural gas to audit billing from utility providers in an effort to reduce billing errors.

PROCUREMENT: Methods for procuring utility services were analyzed using existing contracts and applicability of available programs such as electrical demand-side management (TVA's Limited Interruptable Power (LIP) program), natural gas transport rates, check meter credits for cooling-tower water use and coal purchasing. This analysis showed that electricity on a comparative basis cost almost $15.00 per million BTUs, versus coal at just under $2.00 per million BTUs. Tariff rate natural gas was over $5.00 per million BTUs. This comparison was central in formulating a strategy to eliminate or reduce electrical use wherever possible, to install on-site cogeneration and negotiate special electrical rate programs such as LIP. In addition, building fuel flexibility into the power plant expansion in 1988, provided the option to use natural gas when market price declined to below the break-even price of using coal. This strategy forced our coal supplier to offer reduced coal pricing in return for minimum-use guarantees in tons per year. Because load-growth allowed for continued use of gas when economically practical, this arrangement was ideal for Vanderbilt. Since 1988 the unit cost of electricity has been reduced by over 30%.

GENERATION: The decision to build a plant in 1988 was driven by sustained load-growth due to new construction. The decision to cogenerate electricity was driven by the economics of comparative costing between electricity and coal. Since the cogeneration units could produce sufficient revenue to pay the debt service on the new plant and provide sufficient depreciation reserves to maintain the plant at a high level of reliability, the capital cost of the plant was not passed on to customers through the steam rate structure. Funds that would have otherwise gone to the local electrical utility were used to pay the capital cost of the new plant.

The cogeneration process, also known as combined-heat-and-power (CHP), represents a doubling of efficiency over traditional methods of electrical power generation while reducing CO2 emissions by more than two-thirds. Cogeneration harnesses exhaust heat, which would otherwise be a wasted byproduct of electricity generation, to produce steam and hot water. The steam can be used to produce more electricity without adding more harmful emissions. There is a plaque on the exterior wall of the older portion of Vanderbilt's Owen Graduate School of Management (OGSM) that testifies to cogeneration of power being used in the late 1800's at Vanderbilt in that historic facility which was the original power plant.

The strategy of switching from electrical use to coal provided the opportunity to eliminate older centrifugal chillers powered by electric motors and install absorption chillers that use steam to produce air conditioning. This eliminated the problem of CFC usage (ozone depletion refrigerants) and resulted in an increase in summer steam-plant base load that enabled the power plant to operate at a much higher efficiency. Currently 35% of total campus electricity consumption is generated internally at the plant. The two new generators now being installed at the main plant will increase total internal generation to approximately 45% reducing our purchasing of off-campus electricity.

TRANSMISSION: The transfer of energy from the utility provider to Vanderbilt was also an area of evaluation. It is more economical to receive electrical service at the highest possible voltage. We currently have two voltage systems at Vanderbilt. Service is provided at 69,000 volts from two separate sources and is transformed at the sub-station to 13,800 volts and 4,160 volts. Since 1986 we have expanded the use of the 13,800-volt system by eliminating the Peabody campus substation and consolidating that load to the main substation. There have also been a number of conversion projects that resulted in the elimination of high-cost-direct electrical service from NES to much lower cost electricity from the main substation. This process reduces the inherent line losses associated with lower voltage systems and transformers.

DISTRIBUTION: The methods used to provide utility services to our buildings, such as steam lines, electrical service, natural gas and water were also areas of concentration. Since the installation of the Power plant in 1988, the pressure on the steam-piping system has been reduced from 125 psig to an average of 75 psig. This pressure reduction eliminates substantial waste from line losses and steam leakage; it also improves the efficiency of the steam turbine generator.

We established a policy to use 15,000-volt cable on all electrical feeder replacements, including all 4,160-volt systems to reduce feeder losses and prepare for the opportunity to systematically eliminate the 4,160-volt system.

We have periodically tested our water distribution system for leaks and have determined that water loss from leakage is less than 2%, an excellent number for older systems such as ours.

END USE: This is traditionally the area of major concentration for most energy conservation programs. We consider this one of the important areas of concentration but not the exclusive area. In the mid 1980's Vanderbilt was heavily involved in cooperative efforts with the Department of Energy for cost sharing projects to improve lighting, eliminate control problems in buildings, and improve steam trap efficiency. Vanderbilt received over $1,000,000 in matching funds for the completion of this work. One of the primary tenets of our approach to energy control was that that it made no sense to shut down heating and air-conditioning equipment in the name of energy conservation when occupants were in the facilities. This seemed counter-productive considering that large capital expenditures were made to make buildings comfortable. Our strategy was and still is that we would not require building occupants to reduce energy consumption during peak times unless on a voluntary basis. Our program was centered on producing cost and usage reductions by concentrating on the "back-stage" areas of energy conservation.

SUMMARY: Providing the various utilities in a cost-effective, dependable fashion requires the constant juggling of many variables. Doing so in an environmentally responsible way is very much a part of that equation. Exploring the wide range of options coming forth through technological advances is also going to remain key in striking the proper balance of proven processes and innovative directions as we continue into the future. Engaging the consumers in this process of reducing energy usage and finding improved efficiencies will be a critical factor in our success on this campus and throughout the world.