What’s Up With Water — August 9, 2021

Welcome to “What’s Up With Water,” your need-to-know news of the world’s water from Circle of Blue. I’m Eileen Wray-McCann.

In science news, researchers find that the number of people who have recently moved into flood zones is much higher than previously assumed. A new study, published in the journal Nature, is based on two decades of global satellite imagery focused on flood areas. When those images are combined with population data, they give a new perspective on climate risk. Between 58 million and 86 million people have moved into areas that flooded since the year 2000. That means the number of people exposed to flood risk is ten times higher than previous estimates, which were based on computer models, and not direct observation. Beth Tellman, the study’s lead author, says that the results point to a troubling conclusion: people are creating more climate risk by putting themselves in harm’s way. Tellman said that one reason people move onto land after a flood is that the land is cheap, and might be the only option for people who are poor and marginalized.

In Canada, the federal government is pledging more money to provide clean water to Indigenous peoples. The $8 billion settlement with First Nations groups responds to lawsuits alleging a long history of contaminated drinking water on Indigenous lands. The CBC reports that $6 billion from the settlement will support the extension of reliable water service on the reserves. Some reserves have  endured decades of having to boil their water before using it. The settlement still needs court approval. It also includes $1.5 billion to compensate individuals. The Canadian government had pledged to resolve all boil-water advisories on First Nations reserves by March, but it did not meet that deadline.

In the western United States, the consequences of a severe drought continue to unfold. Last week, the California Department of Water Resources halted hydropower generation from the state’s tallest dam. Water levels behind Oroville dam have fallen to record lows and for the first time, the dam cannot produce electricity. Hydropower generation across California and the American West has declined in this extremely dry year, meaning that electricity providers will lean more heavily on natural gas, solar, and wind power.

Wastewater treatment plants in the United States are in a race against time.

President Biden’s goal is to cut the country’s greenhouse gas emissions in half by 2030, and to reach net zero emissions by 2050. And like all other industries, the clock is ticking for the wastewater treatment sector. To do their part, utilities will have to pull against strong currents. During this period of greenhouse gas reductions, the energy needs of the wastewater sector are projected to climb, due to population growth and tightening water-quality standards.

Luckily, wastewater treatment plants have a source of renewable energy running right through their pipes. They can harness the chemical energy in sewage sludge to produce methane-rich biogas. Utilities can use this energy to power their own treatment works, or they can sell it back to the grid as renewable natural gas or electricity.

The process is a win-win for systems that can afford the upfront costs of these waste-to-energy technologies. A facility that generates its own energy saves on its electricity bill, or even turns a profit by selling the surplus. And utilities can slash their net emissions at the same time, because the process reduces methane emissions from the sewage and displaces fossil fuel-powered energy.

Although these technologies offer economic advantages and potential environmental benefits, utilities in the U.S. have been slower than others around the globe to capitalize on the energy embedded in wastewater. The U.S. is now on the verge of a rapid expansion, but decades of energy policy decisions have left it playing catch-up on the international stage.

Wastewater-to-energy systems start with a process called anaerobic digestion, which treatment plants have long used to reduce the volume of sewage waste. This process creates a sludge which is more easy to treat, and it creates biogas as a byproduct. In recent years, systems began capturing energy from that biogas and using it to produce electricity or natural gas.

Using biogas for energy is not carbon neutral. Burning the methane-rich gas still releases carbon dioxide. But burning the biogas can reduce net emissions significantly. The energy research group EESI estimates that if all wastewater plants in the U.S. that are now using anaerobic digestion installed an energy recovery facility, the country could reduce its annual carbon dioxide emissions by 2.3 million metric tons. That’s the equivalent taking over 400,000 passenger vehicles off the road.

The energy savings are equally immense. Researchers estimate that, by itself, biogas technology could supply up to half the electricity needed by the water sector. Some systems have even achieved “energy positivity,” generating more energy than they consume and selling the rest back to the grid.

The market for this technology is still nascent in the U.S. Fewer than one in 10 of the country’s wastewater plants use biogas for energy. The ones that do are disproportionately the largest ones. Of those, just a handful are net producers of energy.

One reason for the slow uptake is simply that many wastewater-to-energy technologies were developed overseas. But it’s also a matter of economics. U.S. energy policy has not done much to incentivize these technologies. Its efforts to promote renewable energy production are a patchwork of energy credit programs, tax breaks, and development spending. In contrast, some European countries have leaned heavily on tariffs which guarantee renewable energy generators an above-market price for the electricity that they add to the grid.

About half of U.S. states have renewable energy credit programs, which give renewable energy producers a “credit” for selling energy back to the grid. The programs have given these technologies a boost, according to David Goldwater of the engineering consulting company Stantec. But they are still a far cry from the strong incentives seen overseas.

Further complicating the picture is that many wastewater plants in the U.S. are very small. About three-quarters treat less than a million gallons of wastewater each day. An EPA report noted that on that scale, it’s difficult to get a timely return on investment. In the current market, spending several million dollars on an anaerobic digester is an expense that would not pay dividends for most small utilities.

As the market grows, some urge caution about the kinds of energy that biogas projects are used for. Specifically, some environmentalists oppose investments in natural gas because it can encourge an expansion of natural gas infrastructure when the country should be doing the opposite. They argue that energy is better put towards electrification.

From a technological standpoint, however, the field has never looked more promising. Recent advancements have shown that when wastewater is combined with other organic inputs—like food scraps, grease, and farm waste—the reaction becomes even more powerful. This is the strategy used by Oakland, California, saving $3 million on energy bills each year.

Lawmakers are also taking interest. The bipartisan infrastructure bill being debated in the Senate includes a pilot program for such projects. It would award 15 publicly owned water treatment works up to $4 million to create or improve waste-to-energy systems.

And that’s “What’s Up With Water,” from Circle of Blue, where water speaks. More water news and analysis await you at circleofblue.org. This is Eileen Wray-McCann – thanks for being here.