California may have the world’s biggest grid-scale energy storage mandate -- but Canada’s Ontario province may have the world’s most varied one.

Last week, Ontario’s Independent Electricity System Operator (IESO) announced it had awarded five companies a total of 34 megawatts of energy storage projects. Winning projects include some large-scale batteries, similar to projects underway in California, New York, Hawaii and other states with energy storage mandates or incentives. But the awards also include flywheels, thermal energy storage, and what's described as North America’s first large-scale hydrogen energy storage project.

The projects are expected to cost about $14 million per year, or about $42 million over a three-year period, and are the first to be awarded under a broader mandate to bring 50 megawatts to the province by the end of 2014. IESO highlighted that it considers this cost "very competitive relative to comparable storage projects," but didn't break out the costs by individual project.

The participants will be required to provide one of two types of fast-reacting ancillary services for IESO. The first is frequency regulation, a service being provided by batteries, backup generators, variable loads and other non-traditional resources for grid operators like mid-Atlantic PJM.

The second is providing voltage control and reactive power support, a service that’s becoming increasingly important for Ontario and other regions with lots of intermittent wind and solar power to integrate into the grid.

These are different needs than those served by Ontario’s existing 170-megawatt pumped hydro storage system in Niagara, which pumps water with cheap off-peak energy and uses it to generate power during peak demand hours. IESO has already procured a small amount of faster-reacting energy storage, including a project developed by NRStor that has connected 2 megawatts of flywheels from Ontario-based Temporal Power to the province’s grid. Another 4-megawatt energy storage project being developed by Montreal-based Renewable Energy Systems Canada is expected to come on-line this year.

But IESO's new projects are part of a broader push to test out multiple technologies, and could provide important insight into how such different technologies compare to one another in terms of cost and effectiveness -- or, perhaps, can be combined in ways that add up to more than the sum of their parts. Here’s a breakdown of IESO’s selected projects (PDF), along with details on individual projects of note.

- 2 megawatts of hydrogen-based storage from Hydrogenics Corp., a Mississauga, Ontario maker of hydrogen-fueled PEM fuel cells, along with a hydrogen generator technology to turn water into hydrogen through electrolysis, thus creating an energy storage component. Hydrogenics joined German mega-utility E.ON in a 2-megawatt facility that came on-line last year, giving it a reference project to prove its technical capabilities. Its Ontario project will be carried out in partnership with natural gas giant Enbridge, which will jointly develop, build and operate the energy storage facility to provide regulation services to the IESO under contract. CEO Daryl Wilson said in last week’s press release that the new project, set for the greater Toronto area, will be the first of its kind in North America.

- 740 kilowatts of thermal energy storage from Dimplex North America Ltd., North America’s largest maker of electric heaters and equipment. Thermal energy storage involves getting water heaters and other electrical heating loads -- as well as air conditioners, refrigerators and electric-based cooling loads -- to alter their electricity consumption patterns to meet grid needs. That can include pre-heating and pre-cooling buildings or facilities to reduce peak power, or using faster-acting services, aggregating lots of thermal loads that can be switched on and off quickly. Dimplex is no stranger to grid integration -- it’s one of the partners in the wind-balancing PowerShift Atlantic project in Canada’s Maritime provinces.  

- 12 megawatts of both batteries and flywheels from Convergent Energy + Power, a project developer highlighted in last year’s energy storage report from GTM Research. The New York-based company has partnerships with multi-billion-dollar real estate developer and manager Fisher Brothers and contractor Plaza Construction, and has a battery supply agreement with Eos Energy, a startup promising a zinc-air battery that can store hours of energy, something that’s hard for solid-state batteries to manage today. Convergent’s website cites the company's focus on “4- to 6-hour energy storage assets in high-value locations.” That’s a totally different realm of grid service than the fast-acting frequency regulation and voltage support that IESO is calling for. It’s possible that Convergent is putting fast-reacting flywheels together with batteries that offer longer-duration energy capacity, although the company didn’t provide any details on which batteries it was planning to use for its Ontario project.

- 14.8 megawatts of battery energy storage from Hecate Energy, a Nashville, Tenn.-based energy project, and 4 megawatts of battery energy storage from Canadian Solar Solutions, a North American subsidiary of Chinese solar PV company Canadian Solar, round out the project list. IESO’s announcement didn’t include details on what types of batteries would be used by both project developers, but it did note that it was considering a wide range of technologies, including flow batteries, as well as traditional closed electrochemical batteries. IESO’s new storage projects will include high-voltage transmission and distribution grid-connected system, though it didn’t clarify which projects would fit in each category. Ontario Power Generation, the public utility that generates about 60 percent of the province’s electricity, plans later this year to procure the remaining 16 megawatts or so required to meet the province’s 50-megawatt mandate.