Jim Pitts, King County system analyst holds a handful of Loop, a powerful fertilizer derived from wastewater which the county sells to commercial buyers. The carbon-rich product offsets the carbon expended in operating the plant. Aaron Kunkler/staff photo

Jim Pitts, King County system analyst holds a handful of Loop, a powerful fertilizer derived from wastewater which the county sells to commercial buyers. The carbon-rich product offsets the carbon expended in operating the plant. Aaron Kunkler/staff photo

Human waste: Unlikely climate change hero?

King County treatment plant joins effort to counteract effects of carbon dioxide.

Surprisingly, it doesn’t smell that bad.

During a tour on a recent spring afternoon, King County analyst Jim Pitts navigated his way through a network of open-air scaffolds and underground tunnels at one of the county’s wastewater treatment plants in Renton. Despite processing up to 200 million gallons of sewage, runoff and gray water per day, the plant is surprisingly clean and free of offensive odors or waste — even as tons of sludge, garbage and human feces are efficiently processed on the 80-acre site.

On top of cleaning water and returning it to Puget Sound through pipes thousands of feet from shore, the King County South Treatment Plant also produces a product called Loop. Loop is a concentrated and sanitized form of human waste that is used as a highly potent fertilizer for agriculture and forests. It also has the consistency of cake, an observation Pitts was quick to point out as he molded a handful of the treated brown fertilizer into something resembling an animal before dropping it back into a machine.

While this process may seem gross, nearly all pathogens have been removed from the finished Loop, and it is safe to use for many commercial uses across the state, including a collection of farms in Eastern Washington. On top of this, Loop and the wastewater plant are playing a role in a process that is already needed if the planet is to avoid the worst effects of climate change.

Loop is so rich in carbon, it offsets the carbon that’s expended to process the plant’s wastewater. Loop also returns carbon to farmland, allowing crops to grow larger and soak up more carbon.

There are several ways to remove carbon dioxide (CO2) from the atmosphere, many of which are outlined in a report from the Intergovernmental Panel on Climate Change. The report presents a case for keeping global temperatures from rising more than 1.5 degrees Celsius above pre-industrial levels — and if that fails, the need to keep the increase below 2 degrees.

Agriculture, water access and heat-related deaths will be lower at 1.5 degrees. Even still, in areas around the equator, hot days have the potential to be up to 3 degrees Celsius warmer than now with 1.5 degrees of total warming.

In order to stay at or under 1.5 degrees, the world would need to reach net zero emissions by 2050, and for limiting warming below 2 degrees, net zero would need to be met by 2070.

This will require stopping the use of fossil fuels, but also removing carbon from the atmosphere, which will require large investments. James Mulligan is a senior associate with the World Resources Institute, which published a post detailing several techniques to remove carbon from the atmosphere.

“It would be really great to have the technologies available by 2040,” Mulligan said.

Several of these options can be implemented fairly cheaply, but there is a trade-off between cost and effectiveness and feasibility. For example, reforesting is an option. Healthy forests are good at removing CO2 from the atmosphere and storing it in wood and soil. Every acre of restored forestland can rake in around 3 metric tons of CO2 annually.

A recent article in Science Magazine said the U.S. is the largest cumulative emitter of CO2 from fossil fuels, but reforestation has the potential to offset around 20 percent of net annual emissions.

Expanding and enhancing farmland can help store carbon. Farmland is expensive to acquire and maintain and would likely require government subsidies to help landowners. Composting and using products such as Loop can additionally boost carbon storage in farm and forest soils. However, these may not solve global warming on their own, Mulligan said.

“If you think about how much we might be able to get out of those options globally, it’s meaningful,” he said. “It also falls well short of what we need globally.”

Other techniques require more research and development, including using bio-energy like old wood or trash to power energy plants. However, this also requires the plants to actually capture the emissions and store the carbon either underground or use it to make long-lasting products such as concrete.

Other methods can more directly remove large amounts of CO2 from either the air or seawater. Direct air capture involves sucking air into large scrubbers, where it is run through a solution that binds with carbon and removes it. From there, the carbon is turned into pellets and can be stored. Since cleaning units can be stacked, direct air capture provides another major benefit over more natural methods.

“Direct air capture is kind of scalable in a way that none of these other options are,” Mulligan said.

The technology to do this is still expensive. But three companies have already developed systems, and as more join, the price should begin to drop. One recent study cited in the World Resourses Institute’s post found it would cost between $92 to $232 per metric ton to operate direct air capture, and to work as it’s supposed to, it would require using green energy for power. This is still much lower than the $1,000 per cubic ton that was projected around eight years ago, Mulligan said.

It would also require a lot of energy. One of the existing types of direct air capture was estimated to require around 7 percent of all energy in the U.S. But deep decarbonization will require massive penetration of the global energy grid, Mulligan said. Another form of the same idea would scrub seawater of CO2, allowing it to soak up even more from the air. This would require more energy than air scrubbing, but the U.S. Navy already has a prototype in hopes that the captured CO2 could be turned into hydrogen and fuel for vessels.

Some effort like this will likely be necessary in coming years unless the world somehow transitions entirely to clean energy and does away with industries like raising cattle for beef, Mulligan said.

“It would be really great to have the technologies available by 2040,” Mulligan said.

This would allow them to be scaled up by 2050. While a rollout date of 2040 may feel distant, investments should be made now into research and development because there’s up to a 15-year lag between those initial investments and rollout for not only direct air capture, but for forest and soil alternatives as well as seawater capture.

“You’ve got to start doing those now,” Mulligan said.

Air capture alone would require up to $70 million in investments each year, which would scale up to around $250 million annually, according to the institute. This would allow the development and testing of direct air capture systems. Once research and development is done, then it would require public investment to build the required amount of scrubbers.

And unlike other green technology, such as solar panels, which provide a distinct benefit to the private companies building them, technologies like direct air capture of CO2 likely won’t be rolled out en masse by the private sector, according to the institute, because they provide a global public good.

Jim Pitts stands on walkway overlooking filtration chambers at the King County South Treatment Plant in Renton. Aaron Kunkler/staff photo

Jim Pitts stands on walkway overlooking filtration chambers at the King County South Treatment Plant in Renton. Aaron Kunkler/staff photo

More in Northwest

Dane Scarimbolo and Dominique Torgerson run Four Horsemen Brewery in Kent. They were almost shut down in late 2017 by King County, which after years of letting them operate a brewery and taproom, decided they were in violation of county code. Aaron Kunkler/staff photo
Proposed winery ordinance irks King County farmers, neighbors and businesses

Concerns include more traffic, higher land prices, code enforcement and compliance.

U.S. Sen. Patty Murray and Rep. Kim Schrier held a roundtable at the Issaquah Food and Clothing Bank on Oct. 3 to talk about the Trump administration’s plan to further change SNAP food benefits rules and reduce the number of people using them. Aaron Kunkler/staff photo
Murray, Schrier vow to fight White House restrictions on food stamps

Senator and Representative met Oct. 3 at Issaquah Food and Clothing Bank.

King County is not on track to meet its greenhouse gas emissions goals, but emissions also have not been rising with population growth. File photo
King County isn’t on track to meet emissions goals

The goals were ambitious but progress has been slow.

King County is considering ways to increase both the supply of and demand for compost to help divert organic material from the landfill. File photo
King County wants to boost composting market

In 2018, around one-third of material sent to regional landfill could have been composted.

Bellevue is the most expensive place in the region to rent an apartment, according to a new analysis. Courtesy photo
King County cities are among most expensive to rent in Northwest

Bellevue has highest apartment rents; Renton, Kent and Federal Way all saw increases in 2019.

Renton Police Officer Tanuj Soni has been charged with fourth-degree assault with sexual motivation and abuse of office. Photo courtesy of City of Renton
Court documents reveal details of alleged assault by a Renton police officer

Deputy Chief says RPD is performing an internal investigation

Spring Chinook salmon. Photo courtesy Michael Humling, US Fish and Wildlife Service
State awards millions for salmon recovery

Puget Sound counties received more than $45 million.

Grocery store workers picket across King County

Union members are asking Kroger for living wages and more scheduling predictability.

PSE’s battery storage project could help the clean energy rollout

Tiny pilot project in Glacier could eventually be expanded to Puget Sound region.

King County Correctional Facility is located at 500 5th Ave., Seattle. File photo
King County jail’s leaky pipes have national implications

Lawsuit filed in King County Superior Court alleges Aquatherm has been selling faulty pipes.

VoteWA is a $9.5 million program that came online last May and is meant to unify all 39 county voting systems in the state into a single entity. Courtesy image
WA’s new voting system concerns county elections officials

VoteWA has run into some problems in recent months as the Aug. 6 primary election draws closer.

‘Feedback loops’ of methane, CO2 echo environmental problem beyond Washington

University of Washington among researchers of climate change’s effects in global temperatures.