Spain's grid operator shows how CO2 changes as wind and solar vary.

One of the common responses to the article that Mark Lynas and I wrote for the Guardian earlier this week was to question our assumption that a lower fossil fuel share of total generation would result in lower emissions. It seemed obvious to us that if we showed that higher wind generation reduced the number of gas-fired power stations operating it would cut CO2 emissions. This certainty was not shared by some readers. Other national electricity grids provide real time data on CO2 emissions that may help settle the issue. Non-UK data will enable enthusiasts - for want of a better word - to track estimated greenhouse gas emissions and watch how they change as the balance of suppliers on the grid adjusts to higher and lower wind.

I’m a particular fan of the Spanish graphics.

Follow the yellow line with your mouse and the site will provide the CO2 and generation at each time period. The wonderful pie chart on the right adjusts to reflect the changing balance of supply. If you want to check that wind cuts emissions without doing any boring spreadsheets, look through some of the days this week when the wind was blowing and compare them to when it was not. The data for previous days can be shown by adjusting the date in the bottom left hand box. The tabs on the bottom right allow you to look at the CO2 emissions or power output.

Really, really lovely visualisation of data.