Reduced reliance on the conventional power grid and mechanical HVAC systems can save money in the best of times and aid survival in the worst. A focus on energy and thermal innovations at the recent Sustainable Built Environment Conference of the Americas in Toronto naturally drifted into resilience and risk management as presenters outlined technologies that can boost the certainty of electricity supply, passively support comfortable indoor environments and eliminate potential points of failure in systems operation.
Energy storage, phase-change materials and carbon dioxide (CO2) refrigerant exemplify the diversity of products that can have bearing on how buildings use resources, discharge waste and function in both normal and adverse conditions. The session’s three seemingly separate progress reports on the burgeoning technologies pointed to some common themes and collectively offered upbeat news about gains in proficiency, cost-effectiveness and market demand.
Reserve capacity promotes electricity system stability
Practical ability to capture electricity and keep it in reserve for later use has long been viewed as a breakthrough technology for power providers, consumers, the economy and the environment. Energy storage could reduce pressure on existing generation and transmission capacity, make renewable sources more viable and limit financial losses related to surplus supply during times of low demand.
Toronto Hydro is one of many prospective beneficiaries investigating technologies that could be both a critical relief valve and a springboard for sustainable growth. The utility serves one of the largest clienteles among North American electricity distributors, with approximately 740,000 customer accounts, and is currently grappling with intensification of its demand load, aging infrastructure and the operational challenges of adding variable loads from renewable sources into the system.
“It (energy storage) offers the potential to manage a number of things. It’s an opportunity to improve the flexibility of the system,” Jack Simpson, Toronto Hydro’s vice president, generation, told conference attendees. “We’re seeing a huge building boom in the city and, as it continues, it’s stressing our system.”
A 2014 Toronto planning study reported that more than 45,000 new residents had moved into the city’s 17-square-kilometre central district over the previous ten years. Today’s 200,000+ residential population is more than double what was contemplated in 1976 when the Central Area Plan was first adopted. Even with aggressive conservation and demand management, a steadily growing population can quickly refill the manoeuvring space that energy savings have achieved.
Potential vulnerabilities were highlighted in the summer of 2013 when flooding from a severe storm temporarily knocked out one of the two transmission hubs feeding electricity to the city’s central core. The power stayed on thanks to emergency rerouting through the still operational station, but a nearly 900-megawatt drop in capacity had both Toronto Hydro and Ontario’s Independent Electricity System Operator (IESO) asking customers to cut consumption and/or prepare for rotating blackouts.
“The overloading of the system could have caused failure in other connected grids,” recalled Bala Gnanam, director of sustainable building operations and strategic partnerships with the Building Owners and Managers Association (BOMA) of Greater Toronto, after the crisis had passed.
Energy storage could augment system capacity during peak demand periods and help defer the need to invest in expanded transmission capacity, freeing up funds for other priorities. It would also facilitate a consistent flow of renewable sources into the system, avoiding power surges or sags. This will be a priority given the anticipated quadrupling of the city’s current 172 megawatts of distributed generation — largely in the form of solar, cogeneration and district energy — over the next four years.
“Distributed resources can change the nature of the power flow. Solar is highly variable. It changes rapidly and it can flux rapidly,” Simpson explained. “In our view, energy storage is one of the keys for integrating renewables into the system.”
Current pilot projects include a global first — a 660-kilowatt system that converts electricity to compressed air and stores it in underwater balloon-like containers deep in Lake Ontario. Conversion to compressed air and back to electricity is a zero-emissions process, while the underwater structure is credited with creating fish habitat. “It’s environmentally very benign,” Simpson said.
Other pilots, such as a community energy storage (CES) project with funding support from Sustainable Development Technology Canada are testing innovative battery technologies. Such R&D also supports goals to reduce transportation related greenhouse gas emissions.
“The forecast for electrification — electric vehicles, transit — introduces a whole new set of loads into our environment,” Simpson said. “Level 2 or Level 3 chargers (for vehicles) can be a significant load in our system, much more than house loads.”
HVAC holiday with outage contingency
Ryerson University’s Dr. Umberto Berardi sees stress points and overlooked opportunities in Toronto’s downtown intensification, which, he contends are often exacerbated in standardized designs and construction methods.
“There is glass going up everywhere. We are missing a way to add some kind of comfort not relying on HVAC systems,” he observed. “A lot of times we have significant solar gain in our skyscrapers when we don’t want that, then lose it overnight when it is needed.”
His research team has been studying and testing phase-change materials that could enable latent thermal energy storage in new construction and retrofit applications. These are materials — often paraffin wax or salt based — that release stored energy as heating or cooling as they move between liquid and solid state.
When encapsulated in wallboard or used as an aggregate in concrete — “It’s so small that you can put it any porous material,” Berardi noted — phase-change materials passively cool or heat as they melt or solidify, reducing mechanical space heating/cooling requirements. This could be particularly valuable during a prolonged power outage.
Developers, designers and specifiers now have access to an increasing number of products with the necessary combination of strength and stability as a construction material, effectiveness within a practical temperature range and a dropping, although not yet low-cost price point. “Five to 10 years ago, you couldn’t really find a product that was all these things,” Berardi said.
Steven Horwood, vice president, sales and operations, with Neelands Refrigeration Ltd., similarly acknowledged that a switch to carbon dioxide (CO2) refrigerant is not perceived as a low-capital option. However, he countered that assumption with a list of paybacks investors might reap. As Canada and other nation state members of the Climate & Clean Air Coalition move to introduce a global phase-down of hydrofluorocarbons (HFCs), he set out an environmental, operational and business case for CO2.
“We have a natural refrigerant and it has no phase-out. CO2 is non-toxic and non-flammable,” Horwood said. “You eliminate a future refrigerant management issue and you have reduction in risk exposure related to carbon taxes.”
CO2 based refrigeration systems date back to the 1800s, but their market share has been negligible for the past 80 to 90 years. A seeming resurgence — Horwood reports approximately 150 installations across Canada — coincides with regulatory actions targeting ozone-depleting and high global warming potential (GWP) substances and rising energy costs. Potential for heat reclamation and free cooling independent of mechanical compression systems can accelerate the payback, deliver long-term savings and augment system redundancies in response to power failure.
Food retailers have been the predominant adopter of the technology, which addresses a major liability in a sector where it’s estimated operators can lose up to 27 per cent of refrigerant charge annually. “This is the nudge that got CO2 moving again,” Horwood suggested.
He also cited the example a multi-purpose municipal complex encompassing civic offices, community meeting space, a swimming pool and ice rinks, which converted to CO2 refrigeration when it was time to replace an aging ammonia-based ice plant. The new system now provides heating, dehumidification and domestic hot water for the entire facility via heat reclamation.
Meanwhile, CO2‘s free cooling properties have significantly decreased energy costs for the data centre that requires just 9 kilowatts of electricity to provide 3,500 tons of cooling. This also eliminates a vulnerability since a breakdown in a cooling system’s mechanical compressors could have serious repercussions for the safety of critical equipment and the security of the information it holds.
“The people who run data centres love to reduce their points of failure,” Horwood said.
Barbara Carss is editor-in-chief of Canadian Property Management.
