How many Wind Turbines would you need to power a city?

2 Comments

1. Richard says:

   May 20, 2010 at 2:15 pm

   Sounds fairly easy, unless you consider the reality. Some numbers that will help:
   A normal home in a city will average about 1 kW, maybe 1.2 kW. This is about 1,000 Watts
   So you are probably looking at a total average power demand of about 130,000 to 150,000 kW. In this range they start referring to power in terms of MegaWatts (MW), which equals 1000 kW. So your required average Power Demand is about 150 MW, or 15,000 kW.
   The average for a single wind turbine is about 1.5 MW at full power. So if wind conditions are right — and constant — you would need about 100 Wind Turbines to supply the city.

   Now the reality:
   Wind is NOT constant — and is not dependable. I think you need at least about a 7 mph wind, just to begin turning the propellers. If the wind can not remain at better than 7 mph, you get ZERO power. What then? So then in addition to the wind turbines, you need at least 150 MW of "other" generation — such as Natural Gas Turbines (basically a stand alone jet engine) , or a coal fired power plant. So now you have expensive costs for "redundant" generation.
   In addition — this is their "maximum" generation at say a 15 mph wind. What happens when the wind is only 10 mph? You maybe get only 50 MW when you need 150 MW. Big Problem.
   Then, the biggest problem: On a hot 95 degree summer day — when everyone needs power the most — everyone is running their Air Conditioning all out. But now that is the days the wind is NOT blowing. If the wind was blowing — it would be much cooler. So on the hottest days, when the most power is required — the wind does not blow — and the wind turbines produce no power.
   Then the maintenance issues are so bad on these wind turbine units that many companies are just abandoning these wind units in place, and just walking away. They are not economical at all. Without massive "Government" subsidies — free money from the Government — our tax money — no one would even touch these.
   The installed costs are high — the maintenance costs to keep them running are high — there are additional cost for the "back-up" generation that they were supposed to replace, but in reality can’t replace.
   It may be a Politically Correct policy right now — but in reality not a good or rational decision.
2. [deleted] says:

   May 20, 2010 at 2:15 pm

   World’s largets wind turbine: Enercon E-126 produces 6MW of energy. Smaller ones usually 1-3MW.
   Find the average power consumption of a single person and multiply that by 122,000 and divide by the energy produced by one turbine of your choice.