Half of global methane emissions come from highly variable aquatic ecosystem sources
Just a week ago some thirty countries, including the U.S., committed to reducing methane emissions by half between now and 2030. The commitment is based on limited data regarding “sources” of methane. The usual suspects, like methane being flared off natural gas wells, are primary targets. But the actual, largest single source of methane, isn’t being factored in. It is aquatic ecosystems, fresh water systems throughout the planet, including the freshwater lakes we hold so dear for our drinking water and recreation.
Check out this paper by Dr. Judith Rosentreter (et al), a Yale researcher, where the authors argue that ~50% of methane emissions are coming from fresh water sources. Compare it to an earlier study by Dr. Tonya DelSontro (et al.). Note that nutrient-impaired fresh water is currently still “under” the radar of international and national policy managers.
Here’s the nuts and bolts of the issue: any water currently experiencing harmful algae blooms (as in approximately half of freshwater lakes in the U.S.) and which is deep enough to seasonally stratify, as in lakes that are over ten feet deep, generates methane during late spring and summer months instead of carbon dioxide. This is a situation where carbon dioxide, which is less than one twentieth as impactful as methane after correction for “time” in atmosphere, is actually a favorable goal! Nutrient impaired fresh water is today’s leading source of methane. This source of methane accounts for over half of total methane emissions.
Is it addressable? Actually, yes, it is – very much so, and we have the technology to do it. The key is oxygenation. Breakthrough oxygenation technology that generates nanobubbles, and micro bubbles to some extent, can transition water from hypoxic to aerobic year-round, even as water becomes warmer (and therefore less able to hold oxygen) with climate change. Oxygenated water supports the microbes that keep a lake healthy and it starves the microbes that generate methane. It is a straightforward process.
For perspective, consider that Minnesota has some 10,000 named lakes, and about half are currently nutrient impaired. Then there’s Wisconsin, with 15,000 lakes, and the same ratio of nutrient impairment. National policy to motivate states and private stakeholders needs to be developed. Now. Not tomorrow, but “now”, if there’s any real hope to achieve that 50% reduction target.
I’m seriously hopeful that this will be done. My company is currently being supported by the U.S. Dept. of Energy Solar Energy Technologies Office to develop and test an off-grid oxygenation technology. We are blending BioHaven floating treatment wetlands with nanobubble production and solar power. We are halfway through an empirical test tracking our ability to combine these three technologies. It’s exciting. And it’s hopeful.
There’s one other promising related development. FPV (floating photovoltaic) systems are taking hold in Asia and Europe. I note that Asia, particularly China, is the leader around FPV. The U.S. on the other hand, is enmeshed in political squabbling, and is substantially behind most of the rest of the planet. But the U.S. leads in the FTW (floating treatment wetland) category. And blending FPV with FTW represents a scalable means by which to fix the monster methane factories…the Lake Eries, the Chesapeake Bays, the Lake Okeechobees of the world. My vision is that the U.S. advances this blended technology onto the world stage. And that we do so now.
There are many ways private citizens and water quality experts alike can further this effort, from lobbying politicians to sharing on Facebook! Please reach out to me if you share my sense of urgency and want to change the status quo before it’s too late!
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