This week's Economist magazine (and it is a magazine, although they pretentiously call it a newspaper!) has a special on investing in alternative energy.

It's very good but it would be boring to tell you what I agree with. So here are a couple of points that I think are incorrect;

The leader says (sorry, a subscription link);

"The cost of wind power has come down from 8-10 cents to 3.5 - 4 cents per kilowatt hour since 1990"

The price of windpower has actually gone up in the last 2-3 years for 2 reasons;

i) Rise in the price of steel - leading to 20 - 25% increase in the cost per installed megawatt of onshore windpower from $1m to 1.2m and even as high as 1.4 m.
ii) Backup costs have risen. Although these are highly marginal for countries with small wind penetration and high consistent wind speeds such as the UK, the reverse is true for Germany. Backup has to be provided quickly and this means gas which has undergone the mother of all price hikes in the last few years.