Generally, distributed generation (DG) refers to electricity that is provided to the end user by a number of small energy sources. The University of Colorado's smart grid white paper entitled, "Smart Grid Deployment in Colorado: Challenges and Opportunities," http://cees.colorado.edu/sgreport.pdf provides that DG technologies have the potential to mitigate overloaded transmission lines, control price fluctuations, strengthen energy security and provide greater stability of the electric grid. The STAR report highlights the benefits of the plug-in hybrid electric vehicles (PEHV) with respect to carbon emissions reduction. According to the CSU study, however, barriers to PEHV need to be addressed. Some of these barriers include: cost premiums associated with batteries and charging infrastructure and public acceptance to plugging in their vehicles. In addition, to drive growth of PEHV, Federal and state incentives are necessary. Such incentive include: fleet purchases of PEHV by state and local governments, mechanisms to offset the cost premiums of PEHVs and related infrastructure, and support for public education and awareness programs to facilitate integration.
The STAR report highlighted the 2007 NREL study entitled "Costs and Emissions Associated with Plug-In Electric Vehicle Charging in the Xcel Energy Colorado Service Territory" that can be found here: http://www.nrel.gov/docs/fy07osti/41410.pdf. Some of the conclusions as cited in the STAR report are as follows:
- Replacing 30% of the vehicles currently in Xcel territory in Colorado with PEHV that drive 39% of their miles from electricity would increase the total load by less than 3 percent.
- If left uncontrolled, there is the chance that charging would put increased pressure on peaking units.
- Modest attempts to optimize system charging would prevent the need for additional capacity, even in light of a massive penetration of PHEV.
- Most near term PEHV charging would be derived from natural gas.
- The incremental cost of charging equates to about 60 cents to 90 cents per gallon.
- There are significant reductions in CO2 emissions from PEHV.
- One scenario for optimal charging would be to combine off-peak charging to minimize costs, while including some midday charging to increase gasoline savings.
With proper planning PEHV and other battery technologies have the potential to assist utilities with frequency regulation, peak shaving and where lines or transformers are overloaded. According to the study, the impact of increased use of PEHV could be measured by the reduction of carbon emissions.