Behind the Big Ideas: Keena Trowell is tackling the energy storage bottleneck

This story is part of Behind the Big Ideas, a McMaster Engineering series that explores cutting-edge research and introduces the innovative people behind ideas that are changing the world.

Hospitals without reliable power. Children coming home, unable to do homework without a light. When Keena Trowell thinks about the conversation on climate change, she sees a crucial gap.

“We never talk about equity as it relates to energy,” says Trowell, who joins McMaster on July 1 as an assistant professor in mechanical engineering.

“There is a strong link between standards of living and access to energy. I think it’s really important that we focus our efforts on developing clean technologies to meet energy needs globally.”

Trowell’s research explores a full transition away from a heavy reliance on hydrocarbon fuels, while taking on a “bottleneck” that she believes evades people’s attention: the storage challenge.

Batteries may be one of the first solutions to energy storage that come to mind, and they perform well in smaller energy applications, but battery storage is a relatively expensive way to store energy, Trowell explains. Besides, there isn’t enough lithium to store energy on the scale needed to fully transition away from fossil fuels.

Trowell’s research examines a closed loop process of using metals as the energy storage vector. Clean electricity is harnessed to make metals, which can be oxidized to release stored energy — in particular, Trowell has aluminum react with water to create hydrogen.

The reaction also produces solid oxides, which are recyclable. The metal processing is done where and when there is an abundance of clean energy available.

“The big question is: how do we store a lot of clean electricity in a really compact form – and then how do we get that energy back out?”

“How do we make sure that everybody has enough energy, that it’s available to them when they need it, where they need it, and in a way that they can afford it.”

The foundation of a sustainable society

Trowell firmly believes cheap, large-scale energy storage is needed. Ensuring access to affordable, reliable, sustainable and modern energy for all is one of the United Nations Sustainable Development Goals.

It’s what prompted her to pivot from a career as a designer, where she was motivated to choose material and design spaces with sustainability at the forefront.

“Sustainability is linked to energy. How we get our energy is what drives everything else,” she says.

“I really do see energy as the foundation of a sustainable society.”

In her pursuit of clean hydrogen production, Trowell is taking a closer look at supercritical water. She recalls the thrill of seeing scrap metal from an aluminum can remain unchanged in a reactor at 350ºC, only to turn to powder above the critical point of 380ºC.

“It was amazing … The literature says ‘yes,’ but nobody applied it to this kind of system before. So seeing those results and how dramatic that was … there is something specific about this region and it’s worth exploring.”

Trowell envisions noticeable differences in air quality and noise pollution if her research succeeds. It would help tackle the toughest areas to decarbonize, like long-distance transportation, transoceanic shipping, and energy supply to remote communities that aren’t connected to the grid or are still relying on diesel.

“We have this climate crisis that’s happening. In the last 12 months, we’ve seen the highest temperatures we’ve ever seen in Canada. We have literally had towns burned to the ground, and if that wasn’t bad enough, those regions were then immediately flooded.”

“We have a very, very short time in order to resolve it before we start to get these snowballing effects of these changes. So if we think it’s bad now, it’s going to get exponentially worse, and in a relatively short period of time. And I don’t say that to scare anybody, but I hope it’s a motivator.”

“The exciting thing is we have technologies that can help us out. And those technologies are getting cheaper.”

Keena’s sustainability thread

When Trowell isn’t firing up a reactor to explore supercritical water, she’s harnessing the power of her other tools: a needle and thread.

As she sits by a sewing machine, needle bobbing, each stitch marks a conscious effort toward her mission.

Fashion is regularly counted among the top polluting industries worldwide. The constant churn of materials in the textile economy, energy consumption, and ethical questions behind clothes-making productions and certifications are a rabbit hole, she says.

But they’re also essential inquiries that arise from Trowell’s quest for a sustainable life.

Trowell’s hobby of making garments — sewing and knitting — exists at an intersection of her fine arts background and engineering education: it’s a channel for her creativity and requires a thorough understanding of material and highly technical skills for construction.

The difference, she said, is that the solutions come differently and sooner than her long-term research problems that will take years.

Trowell described creating a bathrobe for her niece – a hooded hug made from the plushest terry cloth. She adores a yellow summer dress made of ramie, to keep cool in the heat, with that coveted addition of pockets.

“My passion is making sure as many aspects of my life as I can manage are sustainable,” she said.