The intermittent nature of wind, and therefore electricity generated from wind turbines, makes integrating a large percentage of wind energy on the grid challenging. This issue, of producing renewable energy while maintaining security of supply, must be addressed both by the electricity industry and by government regulators. Since electricity is consumed at the same moment it is created and the mismatch of supply and demand causes frequency variations, generation is constantly altered to ensure that it matches demand. Storage is able to alleviate part of the balancing act required in the supply and demand process increasing the amount of intermittent renewable energy the utility and system operator are able to absorb. This will allow a larger percentage of the electrical demand to be met with wind and other renewable energies.
Wind, with the exception of hydro, is the most prominent source of renewable electricity in Canada and throughout the world.1 Wind has grown quickly over the past 15 years and now supplies 3% of Canada’s electricity;2 it is the most economically viable source of renewable energy with many estimates putting the cost on par with nuclear energy and natural gas for high wind sites.3 Wind has been successfully integrated into the electricity network due to the flexibility of other generation sources, especially natural gas and dammed hydro. Generation which is less flexible include coal and biomass with generation coming from nuclear and run-ofthe-river hydro being very difficult to alter the electricity output level. Strong interconnections to other areas allow a larger amount of wind energy to be integrated as the generation and demand can be balanced over more loads and a larger area. The large area allows the fluctuations in the wind to be mitigated and the large loads allow for a more gradual change in demand. P
rince Edward Island has a high percentage of its load being supplied by wind energy with MECL reporting 17% of its load being supplied by wind energy in the calendar year of 2013.4 Over this same period, Summerside produced 24% of its load from its 12 MW wind farm and some of the electricity bought from NB is produced by PEI’s 99 MW West Cape Wind Farm. An additional 30 MW of wind is currently being commissioned which will bring PEI’s installed wind capacity to 204 MW. This concentration of wind energy, to supply a load which fluctuates between 90 and 260 MW, creates a constant mismatch of supply and demand. PEI imports its required electricity from New Brunswick up to the undersea cable limit of 200 MW, but during times of low production and high demand diesel generators are used to ensure sufficient electricity supply in PEI. During times of high production and low demand the electricity is exported to NB at a relatively low price.
Storage has a large role to play to continue to integrate renewable energy into the electricity network. Along with time-shifting wind power to a time when it is needed, storage can provide a variety of other services which will ensure the security of supply. Storage can be used to ensure voltage levels along lines, reduce distribution and transmission losses, and provide backup power at substations. This report will be of interest to various groups, potential receptors of this report include the utilities, system operators, battery companies, academia, research institutes, and wind farm developers in order to assist in quantifying the value proposition of storage.
