Green Energy

In Nantucket, shards of fiberglass covered the coast for miles after a blade exploded on an offshore windmill, leading to widespread ecological damage. Admittedly it isn't a common event, but it does show the capacity for pollution from wind turbines:

https://www.nytimes.com/2024/07/16/climate/wind-turbine-breaks-nantucket.html

The effects on the lifecycle of offshore wind on aquatic life including whales is a subject of ongoing research:

https://tethys.pnnl.gov/summaries/underwater-noise-effects-marine-life-associated-offshore-wind-farms

It's known that there's a major impact of wind turbines in general on birds, confirmed by several studies:

https://abcbirds.org/blog21/wind-turbine-mortality/

There is also a risk from operational fluids within the wind turbines, and part of the ongoing risk analysis of one wind farm was a scenario where 20,000 litres of dielectric fluid were released into the ocean:

https://response.restoration.noaa.gov/offshore-wind-spill-exercise-held-northeast-region

The nature of the ocean is such that there's a potential to pollute a large amount of water and coastline, making the risks unique to offshore wind, where they would be much more localized in an onshore wind farm.

That being said, it is fair to point out that all forms of industrial scale electricity generation, no matter how "green", will have a potential environmental impact simply by the nature of how massive such operations need to be, so the question is always about finding the least bad option rather than pretending there's any one option that is perfectly positive for the environment.

To be honest though, offshore wind projects don't make any sense in a free market. The cost per MW is significantly higher than the market can support, so the only way to have these things is to take money from someone else to pay the difference. For example, the average wholesale price of electricity in America in 2024 was between 30 and 60 dollars per Megawatt. The cost of offshore electricity is closer to 200 dollars per megawatt. The difference is made up with government grants (which aren't free market) or by power companies charging customers using other forms of electricity more to cover the difference (which is only happening due to regulations and so isn't really a free market mechanism)

This has occurred elsewhere too. In Ontario, many people applauded the massive increase in solar generation, but the price was that the electrical companies paid over 80 cents per kilowatt hour for electricity they then sold at wholesale for closer to 4 cents per kilowatt hour. The difference was paid for by a "global adjustment charge" which massively increased first retail consumers electric bills, and later when that was rescinded somewhat could as much as double the bills of industrial consumers and led to "global adjustment days" where industrial plants totally shut down for a day to avoid the charge.

An example of green energy that could win in the free market running up against government would be hydroelectric. Some of the least expensive electricity in the first world such as Manitoba and Quebec Canada and Norway in Europe, comes from hydroelectric, and unlike solar or wind it can be created at a scale large enough to power an entire region. Moreover, it can be used as a base load which neither wind nor solar can. In many regions where it's practical, lobbyists have ensured that spots that could have good hydroelectric are not allowed to be used for that purpose. There isn't much money in successfully providing cheap power to millions of people.