How using microbes to mine human waste for power could help reduce reliance on fossil fuels

We usually don't think about what happens after we flush our waste, but a team of B.C. researchers is experimenting with ways to convert our sewage into energy.

The team has been working both in the lab and at the sprawling 24-acre Lulu Island sewage treatment site in Richmond, B.C., where they've built a high-tech mini sewage digester that they're seeding with naturally-occurring microbial populations that digest the organic matter.

Biogas, the byproduct of this process, is made up of methane, carbon dioxide and a small percentage of other compounds like hydrogen sulfide, nitrogen and oxygen.

It can be processed into a cleaner form to generate electricity. Those involved say the exciting part is the way they're cultivating the microbial population to produce more biogas.

"We're creating the right environment for them to grow and thrive," said engineer Lillian Zaremba, program manager for collaborative innovation with Metro Vancouver, a regional authority that serves 21 municipalities in B.C.'s Lower Mainland.

The project exists within Lulu Island's sewage plant, which treats millions of litres of effluent from 220,000 homes in Richmond, about 20 kilometres south of Vancouver.

Microbes on the job

Microbiology professor Steven Hallam with the University of British Columbia's Life Science's Institute, says the real magic is microscopic.

"These invisible denizens that live inside of this human constructed, built environment, actually doing all the work, ultimately, that produces the resource, the renewable resource from the waste," said Hallam.

"It's like a circular assembly line. It's an ecosystem."

Hallam, who is part of teams pioneering ways to efficiently extract energy from wastewater that was previously treated and flushed out to sea, hopes projects like this change how societies think about waste.

"We've been taught dilution is the solution to pollution, right?" he said. "I mean, out of sight, out of mind."

The Lulu Island plant is processing the methane they recover and use it to power the plant.

The excess is sold to B.C.'s gas provider, FortisBC, generating about $1 million annually, that's used to keep the facility running. A lot of the research being done involves a large, silver Willy Wonka-esque gizmo.

Nicknamed the "baby digester," the device has been installed at the Lulu Island sewage treatment facility, where it serves as a platform or on-site lab where they can conduct tests. The baby digester is where the microbes — called methanogens — break down the waste.

The resulting methane gas is then piped to another series of structures that include a large, white bubble, where it's cleaned to a point where it can be blended into the gas delivery system. Lulu Island's biogas facility began operating in 2021 and has cost $11-million so far. It is now producing 60,000 gigajoules of energy each year.

In Canada there are 300 active biogas projects from farm or landfill waste that are extracting enough energy to power the equivalent of about half-a-million homes per year, according to the Canadian Biogas Association.

Scaling up

In 2018, microbiologists and environmental engineers from UBC first began the initial microbial research which eventually led to a patented bioreactor plan.

Two research projects using funding from the Natural Sciences and Engineering Research Council and Metro Vancouver's Sustainability Innovation fund collaborated to find ways to extract energy from wastewater, recover heat and ammonia from effluent.

In 2022, the U.S. Patent and Trademark Office granted Metro Vancouver a patent for Syntrophic Enrichment for Enhanced Digestion (SEED), the system or bioreactor that they designed based on experiments done by UBC researchers.

Design of a  new prototype of the bio reactor is underway for testing at the baby digester, and should be complete by 2027. Zaremba says this will allow them to scale up the system and increase methane production by as much as 50 per cent, though they plan to aim for between 15 and 20 per cent to start. She says the goal is to eventually share the technology with 180 other sewage treatment plants in Canada, but she notes that could cost tens of millions.

"If we can prove its success and that it has a positive business case, that means other places with digesters can use it and we can create more renewable, low carbon natural gas so that we can reduce our dependence on fossil fuels and that will help our country achieve its climate goals," said Zaremba.

She says the project helps meet goals in B.C.'s Clean Energy Act, to convert 15 per cent of provincial gas consumption to renewable or low carbon by 2030.

Viable solution or marketing tool?

According to Guru Gurumurthy, a senior analyst with the electricity program at the Toronto-based Pembina Institute, a think-tank advocating for effective clean energy transitions, the concept "certainly seems novel."

But he says this system isn't cheap and notes that "it does add to the greenhouse gas emissions." Gurumurthy sees wind or solar energy as more viable solutions because "they're the lowest cost energy solutions that are available today."

Other critics question if harvesting methane from biogas is a valid climate change solution or just another way to market gas as renewable energy.

Eddie Dearden says that after learning more about climate change about a decade ago, he quit his career as a chemical engineer in the coal industry and switched to sustainable home design.

He filed a complaint with Canada's Competition Bureau calling out gas companies for misleading consumers about the impact of gas use on the environment. He's also one of the plaintiffs suing FortisBC for alleged "greenwashing'' — using marketing to make the company seem more environmentally friendly than it is — and is campaigning for municipalities to change the term natural gas to fossil gas in an effort to make clear to the public the need to phase out the use of the fuel in the face of climate change.

"Essentially, they are manufacturing one of the most powerful greenhouse gasses — methane," said Dearden, who believes Canada needs to move away from using the gas, because it's too difficult to contain.

Zaremba says the Lulu plant now reuses the excess gas that used to be burned off. She says selling it for use prevents that methane from being lost to the atmosphere.

"We're capturing methane, we're cleaning it up and it's being combusted," she said. "It would be great if we could go completely electric and renewable solar or wind. I see this, personally, as a step on the journey in the energy transition."