Arguments
Dear Sara,
Wind turbines are an absolute joke. Has anyone actually figured out the amount of carbon emissions emitted for the entire process from initial construction of the components and land development (construction machinery emissions)? — Mike M.
Hi Mike,
Thank you for this apparent attempt at a “gotcha” question, as it gives me the opportunity to reply with a resounding yes! People have studied, in detail, the amount of carbon pollution emitted during the life of a wind turbine.
In fact, this type of analysis constitutes an entire branch of research known as “life cycle assessment,” with its own handbooks, internationally agreed-upon standards, specialized software, and peer-reviewed journals.
To conduct a life cycle assessment of a wind turbine, or any other product, researchers begin by diagramming each stage of its existence, from manufacturing through end-of-life disposal. Next, they inventory the energy and raw materials consumed at each stage, such as the steel, fiberglass, and plastic needed during a wind turbine’s manufacturing, the diesel burned by ships and trucks in transporting turbine parts from factory to construction site, and the energy used during construction, operation, maintenance, and eventual deconstruction and recycling or disposal.
With this information in hand, researchers calculate the carbon pollution produced during a wind turbine’s life cycle — in other words, its carbon footprint.
Search online for the keywords “life cycle assessment” and “wind turbine” and you’ll retrieve dozens of published papers on this topic. Here’s a non-comprehensive chart of such papers from the past five years:
The carbon footprint of wind turbines
| Study year | Location | Configuration | Rated power (megawatts) | grams of CO2-eq per kWh |
| 2019 | Texas, USA | onshore | 2 | 4.9 |
| 2018 | United Kingdom | onshore | 1.5 | 11.8 |
| 2018 | China | offshore | 3.6 | 25.5 |
| 2018 | China | onshore | 1.5, 0.75 | 8.7 |
| 2016 | Europe | onshore | 2.3 | 6 |
| 2016 | Europe | onshore | 3.2 | 5 |
| 2016 | Europe | offshore | 4 | 10.9 |
| 2016 | Europe | offshore | 6 | 7.8 |
| 2013 | global | onshore | 2 | 8 |
| 2012 | – | – | 2 | 9.7 |
| 2012 | – | – | 1.8 | 8.8 |
This chart shows how much carbon dioxide, per kilowatt-hour of electricity generated, can be attributed to a wind turbine during its life from cradle to grave. If you’re wondering about those awkward-sounding “grams of carbon dioxide-equivalent,” or “CO2-eq,” that’s simply a unit that includes both carbon dioxide and other heat-trapping greenhouse gases, such as methane.
You can see that the results vary by country, size of turbine, and onshore versus offshore configuration, but all fall within a range of about five to 26 grams of CO2-equivalent per kilowatt-hour.
To put those numbers in context, consider the two major fossil-fuel sources of electricity in the United States: natural gas and coal. Power plants that burn natural gas are responsible for 437 to 758 grams of CO2-equivalent per kilowatt-hour — far more than even the most carbon-intensive wind turbine listed above. Coal-fired power plants fare even more poorly in comparison to wind, with estimates ranging from 675 to 1,689 grams of CO2 per kilowatt-hour, depending on the exact technology in question.
There’s another crucial difference between fossil fuels and wind turbines. A coal or natural gas plant burns fuel — and releases carbon dioxide — every moment that it runs. By contrast, most of the carbon pollution generated during a wind turbine’s life occurs during manufacturing. Once it’s up and spinning, the turbine generates close to zero pollution.
What’s more, wind turbines often displace older, dirtier sources that supply power to the electricity grid. For example, after a new wind farm connects to the grid, the grid operator may be able to meet electricity demand without firing up a decades-old, highly polluting coal plant. The result? A cleaner, more climate-friendly electricity grid.
In fact, it’s possible to calculate a carbon “payback” time for a wind turbine: the length of time it takes a turbine to produce enough clean electricity to make up for the carbon pollution generated during manufacture. One study put that payback time at seven months — not bad considering the typical 20- to 25-year lifespan of a wind turbine. Bottom line: Wind turbines are far from a joke. For the climate, they’re a deal too good to pass up.
— Sara
Added July 1, 2021: Reader Bill R. writes, “One thing you didn’t mention, and it is probably significant, is that as the energy mix tilts in favor of renewable energy over time, the energy mix used to manufacture wind turbines (and PV cells & panels) will also see a reduction in carbon intensity, resulting in an even smaller carbon footprint. There will be exceptions — making steel will probably continue to require carbon emissions for a long time — but everything else in the manufacturing pipeline should see reductions.”
Got a question about climate change? Send it to sara@yaleclimateconnections.org. Questions may be edited for length and clarity.
Tom Toro is a cartoonist and writer who has published over 200 cartoons in The New Yorker since 2010.
I see the examples above have the output as Mw, which is rather gilding the lily. The actual energy - MWh as opposed to the rated power is more indicative of the lifetime efficiency re. CO2 equivalence.
Wol,
Wouldn't the "grams of CO2-eq per kWh" lifecycle comparison be the correct comparison?
Note that the comparable values for fossil fuel generating operations are also provided as ranges of "grams of CO2-eq per kWh". And those fossil fuel operation lifecycle ranges would be based on a range of megawatts of rated power and operation locations.
Also note, as the article states, there are internationally developed standards for lifecycle evaluation and comparison.
The analysis is limited to only incremental grams per mwh from each source. Wol makes a valid point with Kw per hour. As is well known, renewables while the incremental cost of less than fossil fuels, they remain intermittent. As such, there has to be constant backup generation to maintain grid stability, even if running at idle. In order to make a valid comparison, it should include to the back up generation.
David-acct,
The opinion that the comparison being "grams of CO2-eq per kWh" is not a valid and rigorously established value for comparing the alternatives would require the following part of the article to be ignored:
"In fact, this type of analysis constitutes an entire branch of research known as “life cycle assessment,” with its own handbooks, internationally agreed-upon standards, specialized software, and peer-reviewed journals."
Did you read and understand the entire article?
I did. And I would expect that the intermittent production of power would be part of the already developed considerations in the field of life-cycle research. Claiming it is not requires the provision of robust evidence, not the simple statement of an opinion and believing all opinions are equally valid.
I also feel obliged to respond to "As such, there has to be constant backup generation to maintain grid stability, even if running at idle." Power delivery into the grid is constantly "brought on line" and "taken off line" to keep the grid reasonably balanced between demand and supply. And there are grids running entirely without fossil fuels. So the intermittent delivery of some renewable power generation is already able to be managed. Batteries and pumped hydro are just 2 ways to do this that come to mind. A person not being aware of that indicates a person with a large opportunity to learn.
btw, I am just a Canadian trained civil/structural engineer with an MBA. But in Canada all engineers are required to have a basic understanding of all fields of engineering. But I constantly pursued learning more about all the fields and many things outside of engineering and business. Learning about climate science is only a hobby of mine. But I am also concerned technically and economically because the increased uncertainties of future conditions because of rapid climate change challenge civil and structural engineering designs and long-term business decisions.
David-Acct:
The problem here is that your question is completely incorrect. When several wind farms in Texas are generating power there are wind forecasts for the future wind and the amount of power that will be generated. These are for a variety of times from 5 minute forcasts to one hour, 6 hours, 24 hours and longer. The power output from the farms is relatively constant over short time periods, say 5 minutes, and slowly changes over longer periods. Thus grid operators do not need to run "constant backup generation to maintain grid stability, even if running at idle." Since they know in advance how much power will be generated by the wind farms, and they have forecasts of electricity usage, they need little extra backup generation.
By contrast, large thermal plants like coal and nuclear plants, often shut down in an instant due to some fault in the plant. Constant backup needs to be run for these plants in case of shut down (nuclear plants have unplanned shut downs about 2 1/2 times per year). For a wind plant they would only lose a singel turbine. In the case of a transmission line failure the back up needed is the same as for thermal plants. Often redundant transmission lines serve to deliver the power with no interruption.
Your question is incorrect. Supporters of fossil fuel have decieved you by feeding you false information. Read about how the Texas grid is currently run and you will see that constant backup generation for all power is not needed. Backup generation for renewable energy is frequently less than that needed for thermal plants.