This is an adaptation of a post from EDF's Energy Exchange blog.
The numbers are stunning: Methane pollution from ammonia fertilizer plants is 100 times higher than what the industry reports, and substantially above what the Environmental Protection Agency estimates for all industrial processes in the United States.
Here's the thing: The fertilizer industry's significant emissions of this powerful greenhouse gas would likely have gone undetected had it not been for nimble Google Street View cars that traveled public roads downwind from such plants in Kansas, Nevada and Oklahoma.
The results from the Google Street View measurements were revealed in a paper published recently in the science journal Elementa. The study, while limited in scope, shows that mobile sensing is an economical way to pinpoint significant emission sources from fertilizer plants and other industrial facilities at a critical time.
Reducing such emissions is vital for rapidly reducing the rate of Earth's warming — and easily collected sensor data could have direct implications for methane reduction policies moving forward in a number of states.
Google Street View cars captured methane data
The fertilizer industry uses natural gas, of which about 95% is methane, both as fuel and as a main ingredient for ammonia and urea products farmers buy for their fields.
Ammonia fertilizer is produced at only 30-some plants in the U.S. Many are located near public roadways where "fugitive methane emissions" carried downwind can be detected — in this case by mobile sensors.
Once the research team discovered a methane plume near a plant, they collected data from Google Street View cars making dozens of laps around the facility. The results were remarkable.
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The team discovered that fertilizer plants emitted, on average, 0.3% of the natural gas they used to the atmosphere. Scaling this emission rate from the six plants in the study to the entire industry suggests total annual methane emissions of 29,000 metric tons — more than 100 times higher than the fertilizer industry's self-reported estimate of 200 metric tons.
This figure also far exceeds the EPA's estimate for the entire U.S. industrial sector of 8,000 metric tons of methane emissions per year.
Next: sensors on school buses?
While the aggregated leaks from U.S. fertilizer plants are relatively small — America's rapidly growing oil and gas industry emits a whopping 13 million metric tons of methane annually – this pollution matters.
For two decades after it's released, methane is 84 times more potent as a greenhouse gas than carbon dioxide. That makes capturing methane leaks a top priority in our efforts to slow climate change.
Today's inexpensive mobile sensors can be deployed on school buses, postal trucks and city vehicles to collect data almost anywhere. Mitigating emissions that these sensors detect is then often as simple as tightening loose fittings or freeing stuck pressure values, past experience has shown – another strong policy proof point.
As John Albertson, a professor at Cornell University and co-author of the study, told me, "With opportunistic sensing, pushing data to the cloud, doing the proper analysis and drawing inferences, we can build environmental policy that is based on evidence."
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