Listed below are all documents and RMI.org site pages related to this topic.
Electricity - Reinventing Fire system operations 8 Items
Together, wind and solar will account for 71% of total U.S. installed capacity in 2050 in Rocky Mountain Institute’s Transform case, up from 4.4% in 2010. Along with hydro, geothermal, and biomass, renewables will meet more than 80% of 2050 U.S. electricity demand.
The dynamic nature of variable renewable resources presents challenges to conventional electricity system operations. Production from wind and solar resources, in particular, is both variable (fluctuating throughout the day according to availability of the “fuel”) and uncertain (weather forecasting is required and by definition is not always accurate).
Production from wind and solar resources, in particular, is both variable and uncertain. However, with good resource and demand forecasting and high availability of flexible demand and supply side resources, it is possible to operate an electricity system reliably with a high percentage of variable renewable energy.
A load-duration curve is a useful tool for comparing the impacts of different renewable portfolios on the grid. In this Rocky Mountain Institute analysis of renewable adoption on the Electric Reliability Council of Texas (ERCOT) grid, a generation mix of 25% solar and 15% wind yields the flattest load-duration curve over the year.
Different renewable portfolio compositions place differing demands on the generation and storage resources of the grid. In hours when variable renewable supply is not enough to meet the full load, the remaining demand must be met with dispatchable generators. When variable renewable supply exceeds the full load, the excess renewable supply must be stored or curtailed. The frequency of over or under-supply is highly dependent on the amount and mix of variable renewables on a given system.
Bulk energy storage can be incredibly useful in integrating variable renewable generation and providing ancillary services to the grid. The ultimate application of a particular energy storage technology is largely determined by its discharge time.
Recent studies evaluating the cost of integrating variable renewables that account for up to 30% of a system’s peak-load range from 0.1 to 1.0¢/kWh.
Rocky Mountain Institute’s four scenarios for the future U.S. electricity system ( detailed here
) all have different penetrations of demand response programs.