U.S. Department of Energy - Energy Efficiency and Renewable Energy
Federal Energy Management Program
Distributed Energy Resource Analysis at Naval Base Ventura County's Building 1512
March 31, 2005
Naval Base Ventura County (NBVC) requested a design assistance grant from FEMP for a preliminary cost effectiveness assessment of possible on-site generation projects. Lawrence Berkeley National Laboratory is executing the analysis using its Distributed Energy Resources Customer Adoption Model (DER-CAM). DER-CAM determines the minimum energy bill that any combination of on-site generation and heat recovery equipment can achieve over a test period, usually an historic year. The key data required are utility tariffs faced by a facility, its hourly electricity and heat requirements (both disaggregated to a few end use categories that allow separation of potential combined heat and power served loads from others), and a menu of available on-site equipment possibilities. The most demanding of these data requirements is often the hourly energy use information. In most cases, including the NBVC study, data sets are developed using building energy simulation. NBVC also had a particularly complex tariff structure. The resulting DER-CAM system recommendation is an idealized system intended to serve as a starting point for more detailed engineering analysis.
NBVC is comprised of two nearby bases located 60 miles northwest of Los Angeles, CA: the Naval Air Station at Point Mugu and the Construction Battalion Center at Port Hueneme, founded in 1941 and 1942 respectively. NBVC employs more than 6,000 civilians, 9,000 military personnel and 1,300 contractor staff.
Port Hueneme's Building 1512 was selected after a site visit by Lawrence Berkeley National Laboratory staff because it has the largest electricity use on the two bases, relatively easy visitor access, opportunities for absorption cooling, and because it has other neighboring buildings with substantial thermal loads that may ultimately become part of a broader microgrid. Building 1512 comprises approximately 136,000 square feet and houses a Navy Exchange (a retail store), the Commissary (a grocery store), and many smaller businesses, notably a food court. The site is similar to a small shopping mall.
Under the contractual electricity and natural gas rates paid by NVBC, and given simulated building end use energy loads and available generating technology characteristics, results indicate that if the building installed a 600 kilowatt DER system, consisting of two 300-kilowatt natural gas fired reciprocating engines with absorption cooling, the annual energy bill savings would be about 14 percent, or $55,000 per year. Electricity purchases from the utility decrease by 3.3 gigawatt-hours per year and natural gas purchases increase by 8.7 gigawatt-hours per year. This appears to be an interesting but not compelling opportunity.
Choice of applicable tariff for the analysis turns out to be critical. A switch to the default utility tariff by Building 1512 alone would almost eliminate the benefit of this project, while it would lower the current bill. Applying a third set of internal energy recharge rates delivers a quite different proposed system entirely, further demonstrating that DER-CAM's detailed treatment of tariff structures can produce results surprisingly different from analyses based on simple approximations of energy costs.
Looking beyond the energy bill to a broader societal view, however, all of the DER installation options suggested for Building 1512 offer substantial efficiency improvements, some to near 65 percent compared to utility central station power generation which is usually around 35 percent efficient. In addition, carbon emission reductions in the range of 20 percent or more than 100 metric tons per year would be achieved considering estimated displaced utility power generation emissions.
A study of this kind is demanding of data inputs and resources, but the resulting system provides a much more valuable starting point for further analysis than sequential economic evaluation of various possible systems. Systematic analysis involving DER-CAM can play a useful role for agencies interested in exploring distributed energy resources.
For more information, please contact Owen Bailey, LBNL.