The advent of beneficial electrification has put natural gas suppliers on their heels. The electric utility industry is touting the trend of reduced CO2 emissions per MWh from electric power generation over the last decade. Plus, the electric industry is promoting the lack of site emissions from wind and solar power and raising questions over natural gas leaks in the pipeline infrastructure. How should suppliers respond to customer concerns about the environmental impact from natural gas consumption?
Carbon Impact: Source Emissions vs. Site Emissions
To begin the conversation about environmental impacts, the case first needs to be made based on a level playing field. This means comparing emissions from source energy, not site energy.
To supply an electron of electricity to our homes or businesses, a coal-fired power plant has to mine and burn coal, produce steam, turn a generator and then deliver the electricity over a relatively long distance through a transmission and distribution (T&D) infrastructure. Similarly, shale gas for a gas-fired turbine generator must be extracted from the ground by a drilling or fracking process, transported to the power plant, and combusted in the turbine to produce electricity. This electricity must also be delivered through T&D infrastructure to homes and businesses.
Carbon dioxide (CO2), a greenhouse gas, is often associated with global warming. According to the Environmental Protection Agency (EPA), only 30% of CO2 emissions in the U.S. came from the production of electric power in 2019 compared to 35% from transportation. But let’s compare electric power generation emissions from coal plants versus combined cycle natural gas-fired turbine generators (CCGT) on a source CO2 equivalent (CO2e) basis.
The CCGT generates electricity directly from the turbine and subsequently from the turbine exhaust, which is used to make steam that powers a steam turbine generator. To properly compare, we will need to account for upstream CO2 and methane emissions from mining, drilling and processing as well as natural gas leaks and emissions from the combustion processes. With that said, a recent study by Stanford University estimated that CO2e emissions from a coal plant are twice that of a CCGT gas-fired plant for the same output (g/kWh) over a 20-year lifecycle. Reduced CO2 emissions per MWh from overall electric power generation is primarily due to natural gas replacing coal.
In addition, coal-fired plants (19% of all sources, the same as renewables) emit much more nitrous oxides (NOx) compared to gas-fired plants and copious amounts of sulphur dioxide (SO2) and particulate matter (PM) as well. NOx is nearly 300 times more powerful than CO2 and 12 times more powerful than methane at trapping heat in the atmosphere. SO2 is a toxic irritant to our lungs and forms acid rain. PM also causes respiratory problems.
The same EPA data also shows that total methane (CH4) emissions from enteric fermentation (cow digestive systems) is greater than either natural gas systems or landfills. Although methane emissions have 25 times the effect on global warming as CO2, they represent only 10% of total source greenhouse emissions (CO2, methane, N2O, HFCs, PFCs and SF6), compared to 80% for CO2.
What Customers Should Know About Beneficial Gasification
Because natural gas is the cleanest-burning fossil fuel, it’s an ideal complement to solar and wind for power generation. As evidenced by the recent power crisis in Texas, low-cost gas-fired power generation is needed to compensate for the intermittent operation of renewables. In addition, both biogas derived from organic materials and renewable natural gas (RNG) are environmentally friendly renewable fuels used to generate electric power.
While renewable energy sources like solar and wind have no site emissions, they do have positive carbon intensity (CI) profiles over their lifecycles due to emissions during manufacturing. According to Stifel Equity Research, RNG using animal waste has a large negative CI lifecycle.
Clearly, the use of natural gas in its various forms can have important environmental benefits compared to the alternatives. Educating your energy utility’s customers about the relative impact of natural gas consumption on the environment compared to other fossil fuels and renewable energy can help them better understand the benefits of natural gas.