Avoiding Distribution System Upgrade Costs Using Distributed Generation
PNNL, in cooperation with three utilities, developed a database and methodology to analyze and characterize the avoided costs of Distributed Generation (DG) deployment as an alternative to traditional distribution system investment. After applying a number of screening criteria to the initial set of 307 cases, eighteen were selected for detailed analysis. Alternative DG investment scenarios were developed for these cases to permit capital, operation, maintenance, and fuel costs to be identified and incorporated into the analysis. The “customer-owned” backup power generator option was also investigated. The results of the analysis of the 18 cases show that none yielded cost savings under the alternative DG scenarios. However, the DG alternative systems were configured using very restrictive assumptions concerning reliability, peak rating, engine types and acceptable fuel. In particular it was assumed that the DG alternative in each case must meet the reliability required of conventional distribution systems (99.91% reliability). The analysis was further constrained by a requirement that each substation meet the demands placed upon it by a one in three weather occurrence. To determine if, by relaxing these requirements, the DG alternative might be more viable, one project was re-examined. The 99.91% reliability factor was still assumed for normal operating conditions but redundancy required to maintain reliability was relaxed for the relatively few hours every three years where extreme weather caused load to exceed present substation capacity. This resulted in the deferment of capital investment until later years and reduced the number of engines required for the project. The cost of both the conventional and DG alternative also dropped because the centralized power generation, variable O&M, and DG fuels costs were calculated based on present load requirements in combination with long-term forecasts of load growth, as opposed to load requirements plus a buffer based on predictions of extraordinary weather conditions. Application of the relaxed set of assumptions reduced the total cost of the DG alternative by roughly 57 percent from $7.0 million to $3.0 million. The reduction, however, did not change the overall result of the analysis, as the cost of the conventional distribution system upgrade alternative remained lower at $1.7 million. This paper also explores the feasibility of using a system of backup generators to defer investment in distribution system infrastructure. Rather than expanding substation capacity at substations experiencing slow load growth rates, PNNL considered a scenario where diesel generators were installed on location at customers participating in a program designed to offer additional power security and reliability to the customer and connection to the grid. The backup generators, in turn, could be used to meet peak demand for a limited number of hours each year, thus deferring distribution system investment. Data from an existing program at one of the three participating utilities was used to quantify the costs associated with the backup generator scenario. The results of the “customer owned” backup power generator analysis showed that in all cases the nominal cost of the DG scenario is more than the nominal cost of the base-case conventional distribution system upgrade scenario. However, in two of the cases the total present value costs of the alternative backup generator scenarios were between 15 and 22% less than those for the conventional scenarios. Overall, the results of the study offer considerable encouragement that the use of DG systems can defer conventional distribution system upgrades under the right conditions and when the DG configurations are intelligently designed. Using existing customer-owned DG to defer distribution system upgrades appears to be an immediate commercially-viable opportunity.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 902412
- Report Number(s):
- PNNL-SA-39886; EO0101010; TRN: US200717%%199
- Resource Relation:
- Conference: DistributTECH Conference and Exhibition 2004, January 20-22, 2004, Orlando, Florida, 26 pages
- Country of Publication:
- United States
- Language:
- English
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MODIFICATIONS
POWER DISTRIBUTION SYSTEMS
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DISPERSED STORAGE AND GENERATION
ECONOMIC ANALYSIS
ELECTRIC GENERATORS
ON-SITE POWER GENERATION
distributed generation
DG
distributed energy resources
DER
capital investment
avoided costs
DG deployment
distribution system upgrades
distribution system cost deferral
life cycle cost
distribution system expansion
electric utility
avoiding distribution system upgrades