As a cleaner alternative to coal and oil, natural gas is enjoying a golden age of consumption. From industrial processes to power generation, methane has become the fuel of choice for a green-washed market.
Although it emits significantly less carbon dioxide when it burns than its liquid and solid hydrocarbon cousins, methane is a serious pollutant in its own right. Also, the natural gas packed inside could be delivered to our homes with a whole lot of nasty guests.
Researchers from across the state of Massachusetts worked on a project tasked with tearing apart the mix of chemicals that are piped into our kitchens, basements and living rooms for cooking and heating.
What they found should discourage us even more from relying so heavily on methane as a clean source of energy.
“This study shows that gas appliances like stoves and ovens can be a source of hazardous chemicals in our homes, even when we’re not using them,” says co-author Jonathan Buonocore, public health scientist at the Harvard Chan Center for Climate, Health, and the Global Environment (C CHANGE).
“The same chemicals are also likely present in leaking gas distribution systems in cities and in the supply chain.”
Methane is what we call carbon studded with a quartet of hydrogen atoms. It forms easily near deposits of larger hydrocarbons, such as those made up of oil and coal.
Because it’s so small, it burns quickly and efficiently to form carbon dioxide and water, making it a convenient source of fuel that can be easily piped into homes and factories.
At least that’s the clean version. In reality, methane itself is a powerful greenhouse gas that can escape from virtually any part of the transportation process.
“It is well known that natural gas is an important source of methane driving climate change,” says visiting scientist Drew Michanowicz of Chan C-CHANGE and PSE Healthy Energy.
“But most people haven’t really considered that our homes are where the pipeline ends and that if natural gas leaks, it could contain harmful air pollutants in addition to climate pollutants.”
The gas that accumulates around fossil fuel deposits and other sources of methane isn’t exactly pure. Beneath these simple blocks of carbon are longer chains of hydrocarbons, including a jumble of complex squiggles, rings and branches.
Volatile Organic Compounds (VOCs) including various alkanes, cycloalkanes and aromatics such as benzene, toluene, ethylbenzene (not to mention inorganic materials such as hydrogen sulfide, helium and nitrogen) contribute to the complex recipe of freshly produced natural gas.
Not all of these compounds are bad for us, but a good proportion, including many of the aromatics, can increase cancer risk in sufficient doses while providing a starting point for reactions that produce atmospheric particles and pollutants like ozone.
What has never been clarified is how many of these more problematic substances, if any, make their way into our homes from the source. Most gas suppliers in the US closely monitor their products to determine their calorific value and meet various standards.
However, these methods don’t tend to track large carbon molecules, making it more difficult to accurately assess the exact composition of the gas we’re burning.
From late 2019 to mid-2021, researchers collected 234 natural gas samples from 69 kitchen ranges in the greater Boston area. Detailed analysis of these samples revealed wide variation across the area and over the entire period.
They shared hundreds of unique compounds, 21 of which — about 7 percent — were considered dangerous in high enough concentrations by federal standards.
They also measured the concentration of odorants, which are used to alert people to high levels of the normally odorless gas. Alarmingly, some of the smaller leaks that do occur in our homes might be too faint to smell at around 20 parts per million.
While the study didn’t go as far as linking leaks or exposure to natural gas to health problems or calculating the potential impact on the environment, it’s enough of a wake-up call to take better care of what could be a growing problem.
“Politicians and utilities can better educate consumers about how natural gas is distributed to homes and the potential health risks of leaking gas appliances and leaking gas lines under streets, and make alternatives more accessible,” says Buonocore.
This study was published in environmental science and technology.