The Role of Energy Storage in Renewable Power Integration Emily Fertig Sharon Wagner Carnegie Mellon University

Energy storage can facilitate renewable energy integration Source: Source: Source: 2

Key energy storage research areas include: Technology-specific issues – Mechanical storage – Electrical storage – Thermal storage Valuation of energy storage 3

Mechanical storage options include: Compressed air energy storage (CAES) Pumped hydroelectric storage Flywheels 4

CAES can enable wind to supply quick, reliable energy Source: 5

CAES has been operating for over 20 years: Huntorf, Germany: 290 MW (1978) McIntosh, Alabama: 110 MW (1991) Iowa Stored Energy Park: 2700 MW (2011) 6

CAES has many benefits for renewables Large storage: smoothes daily variability Ramps quickly: smoothes hourly variability More cost-effective that batteries at GWh scale Many locations with suitable geology in U.S. Key research area: The economic effect of integrating CAES in different electricity markets and varying levels of renewable energy penetration 7

Pumped hydro is limited by location Source: Key research area: Run-of-river hydro storage (all aspects) 8

Flywheels can help with grid angular stability and voltage support Produce kW for seconds Best for high-power, low energy applications Source: Key research areas: Materials development Cost reduction Improved manufacture techniques 9

Key energy storage research areas include: Technology-specific issues – Mechanical storage – Electrical storage – Thermal storage Valuation of energy storage 10

Batteries are wonderful for renewables, but expensive Store and release power across a broad range of time scales Smooth rapid fluctuations Mitigate daily variability Key research areas: Large-scale demonstration projects Cost reduction Source: 11

Plug-in hybrid electric vehicles could act as distributed grid storage Source: 12 Daily load leveling Frequency regulation Reserve Large-scale use: reduce battery costs through competition and mass production Key research areas: Quantify the public and private benefit of using PHEV’s for arbitrage Identify policy incentives necessary to align consumer behavior with maximum social welfare

Key energy storage research areas include: Technology-specific issues – Mechanical storage – Electrical storage – Thermal storage Valuation of energy storage 13

Thermal storage can be hot or cold Source: 0.htm Source:

Demand-side “hot” storage is usually used with solar collectors Store heat energy in hot water for later use Reduce electricity demand for hot water Source: %20heating.gif Key research areas: Quantify potential decrease in electricity demand from wide-spread use Determine optimum system size for max economic returns ID policy initiatives to encourage more deployment 15

A “cold” storage system generates ice to chill water for air conditioning Shift electricity demand for air conditioning from day to night Key research areas: Quantify potential shift in electricity demand from wide-spread use Determine optimum system size for max economic returns ID policy initiatives to encourage more deployment 16 Source: 2/storing-thermal-energy-a-cool-new-way/

On the supply-side, storage is usually coupled with CSP Source: 17

CSP-TES has been operating commercially for 2 years Smoothes hourly variation from clouds Extends plant operation into nighttime peak demand hours Source: use-solar-energy-at-night Andasol 1 in Spain: 50 MW (2008) Key research areas: Reduce costs Quantify long-term effect of TES in CSP O&M costs Evaluate the profitability of different configurations Evaluate the effect of different policy initiatives on decision to use TES with CSP Compare economic & environmental implications of TES for different CSP technologies 18

Key energy storage research areas include: Technology-specific issues – Mechanical storage – Electrical storage – Thermal storage Valuation of energy storage 19

An accurate valuation of energy storage should consider: Air quality and economic benefits of offset generation capacity Firming of renewable power to help fulfill RPS requirements Avoided construction of new transmission capacity and transmission congestion relief from renewables Relief of ramping requirements for base-load generators Overall reduction in cost of ancillary services Deferral of substation upgrades 20

Overall, we recommend that the Renewelec Project should: Quantify storage potential, costs and benefits for different energy storage technologies Identify how grid and power plant operators need to adapt to support storage Examine market and regulatory strategies needed to support storage implementation 21

Emily Fertig: Sharon Wagner: 22