One of the things I've expressed surprise at is the lack of any papers that use real-world numbers to attempt to quantify the co2 savings resulting from wind power. Determined to see if this could be done, I took the better part of a day and closely analyzed Denmark's voluminous numbers to see if I could tease the answer out. And I think I've been successful. The final answer I got is 280g/kw-h generated, which is not bad but is far below the wind industry's claims (which range in the 800-1000g range), and a bit below "mixed" numbers (which range around the 500g mark).

Denmark is unique in its location, neighbors and electrical connections. They are able to sell their excess power to Germany and Norway, where it can be either used or stored (via hydro). Unfortunately those sales are at off-peak (aka cheap) times, while the power is repurchased back at peak (aka dear) times, burdening the Danes with Europe's highest electrical rates. It probably represents the best result that could be reasonably attained, so my result (as low as it is) is probably the highest that can be reached in a reality-based manner.

Certainly Denmark can claim a fairly dramatic reduction in CO2 emissions for each mw-h generated from 1990 to 2004; I calculated it going from 1.96mt/wm-h to 1.41mt/mw-h in 2004. They say it is due to 2 factors: changing fossil fuel from coal to mostly natural gas, and wind power. My effort was mostly to separate these 2 factors out and see how much gain was due to which.

Perhaps more important than my result is how I got to it. Here are some of the decisions and assumptions I had to make. (1) I considered only electrical generation and the CO2 emissions from that. (2) To generate the CO2 numbers, I had to work backwards from the fuel consumption and hone in on the likely CO2 emissions of the different fossil fuels. (3) I used actual observations, not the adjusted ones that are often quoted. (4) I couldn't find the total electrical production for Denmark in 1990, so I figured their average efficiency and used that number (about 47%) to calculate it from the fuel consumed.

The basis of most of my data is the Denmark ens.dk web site, in particular their annual statistics pages at Chapter 4 and Chapter 6. The following figures are from those reports. The main figure I used was the "Fuel Consumption in Electricity Production".

I then referenced the "Electricity Production by Fuel" figure to calculate how much electricity was generated.

These 2 figures almost sound like they show the same thing, but after looking at them closely, one appears to be inputs and the other is outputs. Dividing the numbers in the second one by the numbers in the first one provides an efficiency rating. I originally thought the 43+% I calculated for coal was too high, but I subsequently learned that Denmark coal plants really are that efficient. Unfortunately, this improved efficiency (Denmark upgraded a number of their coal plants to Combined Heat and Generation) may have produced part of the co2 savings that I assumed were due to the wind turbines. So my assumptions are perhaps even more optimistic than I thought - see assumption #4 above. I took the calculated production, adjusted it for all the biomass etc. inputs and then calculated the total emission to production ratios for 1990 and 2004.

I then lifted out the CO2 savings due to the fossil fuel changes, and assumed that whatever was left was due to wind. During this process, I checked to make sure that my emission calculations were consistent with Denmark's observed numbers, as shown here.

I do have some misgivings about these calculations. One concerns the two tables and how they relate to each other. I would have liked to simply compared those efficiencies and drawn my conclusions from there, but the two tables have matching numbers only back to 2000. I could have done this study using 2000 and 2004, but in that short of a period the wind inputs didn't change enough (compared to the yearly variations) for me to draw any conclusions. Another concerns the assumptions I had to make with regard to the coal plant's efficiencies.

If anyone has any corrections or suggestions, please let me know. I'm always willing to improve the accuracy and my understanding of these numbers.