Rooftop turbines aim to capture power in windy cities

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This week:

• Rooftop turbines aim to capture power in windy cities
• A global pledge to make travel more sustainable
• How a former ski hill in southern Alberta became key to studying climate change

Rooftop turbines aim to capture power in windy cities

There's a reason they're called wind "farms" because wind power is usually generated in rural areas, using turbines with massive blades that are tall and noisy.

That design doesn't really work in cities, where densely packed buildings tend to block and redirect wind, making it gusty and variable in speed and direction, says Ted Stathopolous, an engineering professor at Concordia University in Montreal who studies the effects of wind on buildings.

That poses a challenge for traditional turbines, which are designed to harness wind travelling horizontally at relatively high speeds in a consistent direction.

Yet cities are home to millions of people who use power, and Stathopoulos says harnessing local wind could provide resilience when storms take down transmission lines.

So far, tests of urban wind turbines have failed to generate much power, thus discouraging investment. But Stathopoulos says relatively little has been done to optimize urban locations to generate wind power. "There is a lot of potential for development there."

A number of companies are trying to take advantage of that with innovative designs. Here's a look at a few.

Flower Turbines, based in New York City, creates vertical wind turbines that look like large, skinny tulips (see gif above). They're designed to be installed on the ground or on a flat roof. The vertical-axis turbines can start generating power at low wind speeds of just 0.7 metres per second, compared to 3.5 m/s (or 12.6 km/h) for traditional wind turbines. The company sells one- and three-metre-high models in the U.S and Europe. (See video here.)

PowerNEST(see gif below), made by IBIS Power in Eindhoven, the Netherlands, is a rooftop unit that integrates wind and solar in what the company describes as a "flowing kinetic sculpture." It uses fins on the edges of the rectangular frame to direct air to vertical turbines that sit underneath a roof of solar panels. The wind helps cool the panels and increase their efficiency. The company says the system can capture six to 10 times more electricity than rooftop solar panels alone. So far, the company has created a handful of demonstration projects in the Netherlands. (See video here.)

Aeromine Technologies, based in Houston, has a technology with no external blades, so it isn't really a turbine. Instead, it captures air between stationary, hollow airfoils (similar to those used to stabilize race cars) and funnels it to a partially enclosed propeller underneath. The company says this harnesses and amplifies building airflow in wind speeds as low as 2 m/s (or 8 km/h), while also allowing the unit to generate power at high wind speeds in "most extreme weather conditions." The company has a pilot running in the U.S., and says it will be announcing several pilots in Canada later this month.

O-Wind, made by O-Innovations in Lancaster, U.K., was featured in one of What On Earth?'s first issues, in 2018. Its inventors won the International James Dyson Award that year for a soccer ball-sized prototype designed to harvest wind from any direction when mounted on the side or roof of a building. Since then, they have honed and patented the design and produced a larger functional prototype. They have received grant funding to install pilots in urban areas.

There has been at least one Canadian design: RidgeBlade, made by Kingston, Ont.-based The Power Collective. (As of January 2023, CBC News has been unable to reach the company; the phone and email listed on its website have been disconnected.) The RidgeBlade was designed to use the existing surface of a pitched roof to focus wind and boost its speed as it travels through turbines along the roof's ridge. "Placing the turbine in this high-flow area means that up to nine times the energy is available to it compared to a [traditional horizontal-axis wind turbine] system," the company said on its website, which offers residential and commercial modular units for sale.

Emily Chung

Reader feedback

In response to Molly Segal's piece on the growing interest in solar power generation in Alberta, Brian Collinson wrote:

"As an Alberta native who left at the very height of the oil boom, I was fascinated by this account of how solar power has taken off in my province of birth. It's an intriguing example of how, if you create the right conditions, renewables can flourish. I hope legislators and regulators in other provinces and territories are taking note!"

Write us atwhatonearth@cbc.ca.

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The Big Picture:A pledge to travel more responsibly

In these dreary days of winter, thoughts inevitably turn to warmer climes. But given the environmental cost of flying and visiting increasingly precarious destinations, there is growing awareness that something needs to be done to make travel more sustainable.

One of the legacies of the COP26 climate summit in 2021 was the Glasgow Declaration on Climate Action in Tourism, an initiative meant to decarbonize the tourism sector and protect ecosystems. As the declaration's founding document states, "rebalancing our relationship with nature is critical to regenerating both its ecological health and our personal, social and economic well-being."

So, who has signed on? Tourism boards, tour operators and travel agents, mainly, including Destination Qubec Cit and Turisme de Barcelona (see photo below) and brands like Expedia and Contiki. At this time, the declaration has 700 signatories who have committed to implementing climate action plans within a year of signing.

Those initiatives can include helping restore natural habitats and using more renewable energy in their operations. The goal of the Glasgow declaration was to urge travel organizations to commit, as a united sector, to aligning with broader UN ambitions to make the world net-zero by 2050. But as with many climate pledges in the travel sector, this one is still voluntary.

Hot and bothered: Provocative ideas from around the web

• Here's some good news about a successful global environmental agreement: the ozone layer will have fully recovered in most of the world by 2040, a UN assessment has found.

• Floating solar farms are already popular on lakes around the world. Now, scientists and engineers are trying to develop solar panels that work in rough water, so they can float on the ocean.

• Is your food causing environmental destruction? In Europe, this may soon be less of a worry. The European Union has agreed on a landmark law to prevent companies from selling beef, coffee and a handful of other commodities in the EU if they're grown on land where forests were recently cleared.

• Freetown, the capital of the African country of Sierra Leone, has appointed its first chief heat officer to help it cope with rising temperatures and other climate-related changes.

How a former ski hill in southern Alberta has become key to studying climate change

Virtually every snowflake that falls on Fortress Mountain in Alberta's Kananaskis region is recorded and watched.

"We're in a time when we get extreme weather and a changing climate," said John Pomeroy, director of the University of Saskatchewan's centre for hydrology. So "we try to follow every drop of water, every flake of snow, and see where it's going."

The centre's Coldwater laboratory has outfitted this former ski area in the Alberta Rockies with instruments placed on ridges, glaciers, valleys and creeks. The data collected here is being used to form new and more reliable climate prediction models for flood, drought and water supply forecasting.

Nowadays, these models are based on physics rather than historic observations.

"If you have a model that's based on physics, you can throw at it a weather pattern or a climatic condition that we've never seen and the laws of physics still hold," Pomeroy said.

Research technician Kieran Lehan says his main role is managing 35 hydrometric stations not just on Fortress Mountain, but in other parts of Kananaskis and the Icefields Parkway. It's often a case of figuring out how to keep stations and sensors running through freezing temperatures.

"When you have this many stations and this many sensors things just go wrong, especially in the winter," Lehan said. "I have no shortage of work."

If temperatures dip low enough, batteries at some stations need to be swapped out. And that's a heavy lift: a camping cooler full of car batteries needs to be dragged to the site and buried in deep snow as a backup if wind and solar power fail.

But data isn't just collected from the ground. Madison Harasyn, who is a research technician, pilots drones equipped with various sensors, including a Light Detection and Ranging (LiDAR) sensor.

"We do take snow surveys over different locations in the Fortress Basin just to verify snow depth and density in those areas," Harasyn said. "It's basically like taking a million samples of snow depth over the fortress basin in one day versus going and doing it yourself and then disrupting the snow as well while physically measuring it."

At every station, Pomeroy has a laundry list of ongoing experiments as well as discoveries researchers with the centre for hydrology and experts from other institutions have made here.

Discoveries like how the tree line in Kananaskis is creeping higher. Trees hold snow in place, but the snow that shrouds the tops of trees and is caught in branches often evaporates into the atmosphere never making it down the streams as meltwater.

Pomeroy said they've learned how avalanches transport snow into lower elevations where nice, slow-melting reservoirs are created. He also pointed out a lake that's empty in winter but full in spring. Pomeroy said it's not fed by a stream, but from groundwater stored inside a mountain.

All of these discoveries mean more understanding, and more data to plug into the complex formulas the Coldwater lab develops to create forecasting models and shares openly with governments here in Canada and across the world.

With new technology, like supercomputers, Pomeroy said scientists are now able to manage complex calculations quickly.

"There will be more floods in the future and hopefully we'll be able to predict them better than we have in the past."

Helen Pike

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