UK Government slashes renewables incentives

Bill Taylor:
You ask

without checking arent windmills something like 12th century technology?

No, wind turbine technology is much older than that although one significant develipment of the technology did occur around 1200AD.
Vertical-axis windmills to mill corn were first developed by the Persians around 1500 BC, and they were still in use in the 1970’s in the Zahedan region. Sails were mounted on a boom attached to a shaft that turned vertically. The technology had spread to Northern Africa and Spain by 500 BC.
Low-speed, vertical-axis windmills are still popular in Finland because they operate without adjustment when the direction of the wind changes. These inefficient Finnish wind turbines are usually made from a 200 litre oil drum split in half and are used to pump water and to aerate land. Low speed vertical-axis windmills for water pumping and air compressing are commercially available.
The horizontal-axis wind turbine was invented in Egypt and Greece around 300 BC. “It had 8 to 10 wooden beams rigged with sails, and a rotor which turned perpendicular to the wind direction” . This type of wind turbine later became popular in Portugal and Greece. Around 1200 AD, the crusaders built and developed the post-mill for milling grain (and I suspect it is this development to whicht you refer). The turbine was mounted on a vertical post and could be rotated on top the post to keep the turbine facing the wind.
This post-mill technology was first adopted for electricity generation in Denmark in the late 1800’s. The technology soon spread to the U.S. where it was used to pump water and to irrigate crops across the Great Plains. During World War I, some American farmers rigged wind turbines to each generate 1 kW of DC current. Such wind turbines were mounted on buildings and towers. On western farms and railroad stations, wind turbines for pumping water were between 6 and 16m high and had 2 to 3m diameter. With 15kmh wind speed, a 2m-diameter turbine operating a 60cm diameter pump cylinder could lift 200 litres of water per hour to a height of 12m. A 4m diameter turbine could lift 250 litres per hour to a height of 38m.
This brief history demonstrates that wind turbines can have useful niches to the present day. For example, small wind turbines can be used to economically pump water or generate electricity in remote locations distant to – or disconnected from (e.g. on boats) – an electricity grid supply. But wind power lost favour when the greater energy concentration in fossil fuels became widely available by use of steam engines.
Wind power has recently found favour for large scale electricity generation in some places, but such use is uneconomic and impractical. Today, if wind power were practical and economically competitive with fossil fuels, then oil tankers would be sailing ships. Japan has conducted several studies to ascertain if use of automated sails could assist modern shipping. These studies have demonstrated that available wind power is so small a contribution to the powering of a ship that the systems to obtain it cannot recover their capital costs.
I hope this is an adequate answer to your question.
Richard