: "In order to power a city the size of NYC you'd need 57,000 acres; and who knows the astronomical amount of land you would need to power the entire US." Contact online >>
: "In order to power a city the size of NYC you''d need 57,000 acres; and who knows the astronomical amount of land you would need to power the entire US."
: "The carbon footprint on wind [energy] is significant."
How green is wind power? It''s not a simple question. Of course the wind blows without carbon emissions, but catching it isn''t easy. Building and erecting wind turbines requires hundreds of tons of materials — steel, concrete, fiberglass, copper, and more exotic stuff like neodymium and dysprosium used in permanent magnets.
All of it has a carbon footprint. Making steel requires the combustion of metallurgical coal in blast furnaces. Mining metals and rare earths is energy intensive. And the manufacture of concrete emits lots of carbon dioxide.
In the case of wind and solar power, those emissions are nearly all front-loaded. That contrasts with fossil-fueled electric power plants, where emissions occur continuouisly as coal and natural gas are combusted.
It''s a big distinction. But how significant? Analyst Deepa Venkateswaran at Bernstein Research looked into it.
Citing data from the likes of National Renewable Energy Laboratory, Vestas, Siemens Gamesa Renewable Energy, and Bernstein estimates, Venkateswaran determined that the biggest contributors to the carbon footprint of wind turbines are steel, aluminum and the epoxy resins that hold pieces together — with the steel tower making up 30% of the carbon impact, the concrete foundation 17% and the carbon fiber and fiberglass blades 12%.
Good news: amortizing the carbon cost over the decades-long lifespan of the equipment, Bernstein determined that wind power has a carbon footprint 99% less than coal-fired power plants, 98% less than natural gas, and a surprise 75% less than solar.
More specifically, they figure that wind turbines average just 11 grams of CO2 emission per kilowatthour of electricity generated. That compares with 44 g/kwh for solar, 450 g for natural gas, and a whopping 1,000 g for coal.
But beating them all is the original large-scale zero-carbon power source, nuclear power, at 9 g/kwh.
Thanks to technology, these stats aren''t static. Offshore wind turbines are becoming enormous, with General Electric''s GE Haliade X featuring blades 360 feet long and generating 14 megawatts. The carbon footprint of such monsters could get as low as 6 g/kwh.
And they could be trending lower, thanks to the advent of so-called green steel.Swedish companies Hybrit and H2 Green Steel are investing billions to make millions of tons a year of green steel. Instead of burning metallurgical coal to fire a traditional blast furnace to reduce iron ore into pig iron, they will use green hydrogen electrolyzed via renewable power.
They''re working as well on reducing the carbon footprint on the backend of wind and solar projects — by recycling old photovoltaic panels and turbine blades.
In Italy a company called Sasil aims to recycle 3,500 tons of old solar panels a year, while Veolia in France intends to increase the capacity of its panel recycling to 4,000 tons a year. It''s as easy as unscrambling an egg. At Arizona State researchers are working on electrochemical processes to extract metals like tin, copper and lead from solar cells by dissolving them in baths of nitric acid, then hydrofluoric acid and sodium hydroxide.
They won''t run out of material — the International Renewable Energy Agency predicts that we''ll have to deal with a cumulative 78 million metric tons of antiquated solar panel waste and tens of millions of tons of old turbine blades by 2050
Those blades, made of carbon fiber and fiberglass composites held together with plastics, are tougher to recycle. Wind farm operators tend to upgrade or "repower" their turbines about once a decade, which results in piles of old blades that typically end up being landfilled.
Increasingly these old blades are being put to modest new use — broken down, ground up and added to cement as filler. All progress on the long path to net-zero.
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.
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.
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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:
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.
P.S. Many of you are wondering about the carbon footprint of other electricity generation technologies, such as solar panels, nuclear, and hydroelectricity. The National Renewable Energy Laboratory has a superb, though a bit dated, page for comparing the carbon footprints of various electricity generation technologies.
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.”
Tom Torois a cartoonist and writer who has published over 200 cartoons in The New Yorker since 2010.
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