312 Electricity Cost Modeling Calculations Customers," 12 participants for all 12 months in 2007 experienced an annual savings of between 7% and 12% compared to the fixed rate other residential customers received. RRTP participants are billed for the electricity they consume based on hourly wholesale market prices. They have access to hourly pricing information via the Internet and pricing alerts via text messaging and email. Participants may choose to make adjustments in their electricity usage based on the hourly prices. For instance, if pricing alerts indicate that electricity prices could reach or exceed 13 cents/kWh, about 2.5 cents higher than Commonwealth Edison's fixed rate, customers can save money by shifting their electricity usage to lower-priced hours later in the day. 10.8 CONCLUSION But, with all of this said, the need to price electricity efficiently is still at the forefront, especially given that emissions of greenhouse gases from (60%) coal-fired power plants are the worst offenders (emissions from a coal-fired generating plant are almost twice that from natural gas to fuel the generation of electricity). Given this, should not the customers of uti- lities with coal-fired generation pay more for their electricity (and not just via below-the-line items, such as cost-recovery mechanisms for environ- mental or automatic adjustments for fuel costs) than ratepayers in the ser- vice territories of lower-emitting utilities? In other words, should not consumers pay more for electricity generated from "dirty sources" than that generated from "clean resources"? And, in the case of investor-owned utilities, should there not be a higher return to the shareholders of firms that have made investments in renewable resources and other efficiency- improving investments? It is often said that energy efficiency is the lowest-cost option; however, energy efficiency requires investment in more energy-efficient appliances and equipment, which tends to command a relatively higher cost. 13 My opinion is that conservation is clearly the lowest-cost option; however, for this to occur there must be a price signal to which end users can respond. At the very least, this means that energy charges reflect 12 13 (www.reuters.com/article/pressRelease/idUS274507þ31-Jan-2008þPRN20080131). If you perform a life-cycle cost analysis you may be surprised; you may want to review Chapter 9, "Load Forecasting--The `Demand' for Electricity," for a discussion of discrete choice models and the theory underlying the trade-off between installation and operating costs in terms of appliance choices.