Natural Gas Appliances and Global Warming

For several years the U.S. Department of Energy has been promoting the use of induction for home cooking. Conventional residential cooking tops typically use gas or resistance electric heating elements, (the ubiquitous coil) to heat food.  The government estimates that gas stoves are approximately 32% efficient in their energy use and electric stoves are 75-80% efficient.  Residential induction burners consist of an electromagnetic coil that creates a magnetic field when turned on. Compatible cookware is heated when it is within the magnetic according to the DOE induction cooking 85% efficient. Less heat is lost to the surrounding air, providing an additional energy efficiency benefit by reducing the workload for air conditioning equipment. A cooler cooking top surface also makes induction cook tops safer to work with than other types of cooking tops. Finally, because the cookware itself is the source of heat, it reaches desired temperatures more quickly and provides faster cook times.

I had always dreamed of a kitchen with a commercial or commercial style stove. When I had saved up the money to upgrade my kitchen, I realized that the kitchen centerpiece stove was not my best choice. First of all, it is a warming world and those stove throw off lots of heat, second I live in a rural area where natural gas (methane) is not available, instead we have a propane tank and third commercial stoves are simply not good at low simmer, my preferred cooking style. I make lots of sauces, gravy, stews and soups. Gas burners (especially propane with its three carbons) burn too hot. So, in 2018 when I updated my kitchen I installed an induction cook top. I have been amazingly happy with that choice. The cooking is all I had hoped. What I had not anticipated is how easy and fast it is to clean, and the bad kitty cannot accidentally turn it on.

Now scientists are taking a closer look at cooking with gas. Natural gas is a popular fuel choice for home cooking and has always been considered better than conventional electric. It has the reputation that “real cooks” use natural gas. Nationally, over 40 million homes (about a third) cook with gas. Natural gas appliances release methane and other pollutants through leaks and incomplete combustion. These appliances warm the planet in two ways: generating carbon dioxide by burning natural gas as a fuel and leaking unburned methane into the air. A recent Stanford University study found that the methane leaking from natural gas-burning stoves emit up to 1.3 % of the gas they use as unburned methane.

According to the U.S. EPA, methane is the second most prevalent greenhouse gas and accounted for about 10% of all U.S. greenhouse gas emissions from human activities. Methane is emitted by natural sources such as wetlands and the breakdown of organic material, as well as from leakage from natural gas systems, growing rice, waste disposal and the raising of livestock. Methane is a powerful greenhouse gas and is 25 times more effective than carbon dioxide at trapping heat over a 100-year period. While it does occur naturally, major human-generated sources include landfills, refineries, oil and gas fields, natural gas infrastructure, dairies and wastewater treatment plants.

This work came out of Dr. Jackson’s lab at Stanford University where they are working to measure and reduce greenhouse gas emissions through the Global Carbon Project (globalcarbonproject.org), which Jackson chairs. Some of their work is directly aimed at measuring and reducing methane emissions from oil and gas wells, city streets, and homes and buildings. According to Dr. Jackson and his colleagues, curbing methane emissions will require reducing fossil fuel use and controlling fugitive emissions such as leaks from pipelines and wells, as well as changes to the way we feed cattle, grow rice and eat. “We’ll need to eat less meat and reduce emissions associated with cattle and rice farming,” Dr. Jackson said, “and replace oil and natural gas in our cars and homes.”

The scientists measured methane and nitrogen oxides released in 53 homes in California- not the biggest of sample. Their sample group included 18 brands of gas cooktops and stoves ranging in age from 3 to 30 years old .Measurements were taken during combustion, ignition, extinguishment, and also while the appliance was off.  

The scientist found no relationship between the age or cost of a stove and its emissions. What they did find that more than three-quarters of methane emissions occurred while stoves were off, suggesting that gas fittings and connections to the stove and in-home gas lines are responsible for most emissions, regardless of how much the stove is used. They should have probably examined the age of the interior piping and fittings in the home, but that was not part of the study. California does not require a building permit when you replace gas appliances the way we do here. So the fittings in California are not tested regularly over time.

The scientists found the highest emitters were cooktops that used a pilot light instead of a built-in electronic sparker. Methane emissions from the puffs of gas emitted while igniting and extinguishing a burner were on average equivalent to the amount of unburned methane emitted during about 10 minutes of cooking with the burner.

Larger stoves (those trophy kitchen appliances )tended to emit higher rates of nitric oxides. The scientists estimated that people who don’t use their range hoods or who have poor ventilation can surpass the EPA’s guidelines for 1-hour exposure to nitrogen dioxide outdoors (there are no indoor standards) within a few minutes of stove usage, particularly in smaller kitchens.

Dr. Jackson encourages switching to electric stoves to cut greenhouse gas emissions and indoor air pollution. I switched to induction to get fabulous cooking,  easy cleanup and energy efficiency. I  maintain propane in my home to power my backup generator, a propane furnace, a gas fireplace (I'm thinking about it) and hot water heater. Without electricity I have no water-my well pump does not work, my air heat pumps do not work, and all my kitchen appliances and freezer go down. We have lost power for several days after a storm in the winter and once in the summer. Because I have the generator and  backup systems, my pipes did not burst, my septic pump continued to operate and life went on.