Additionally, since the change toward these expensive and unreliable energy sources is all about reducing carbon, the real reductions need to be considered as well.
Here is an interesting real-world scenario. Of particular interest is the author’s comment about a possible correlation between Ireland’s high energy costs and high unemployment. What do you think?
The Role Of Wind Power Generation In Ireland
EirGrid is the state-owned commercial electrical transmission company for Ireland. The company as of August 2009 generated 12 percent of its electricity by renewable(10 percent from wind and 2 percent hydroelectric). The company plans to generate 40 percent of their electricity by renewable by the year 2020 which would put them at the forefront for Europe if they achieve that goal.
By the end of 2009, EirGrid had a connected wind capacity of 1260 MW and contracted for an additional 1415 MW by 2015. The non-wind generated electricity at the end of 2009 was 6392 MW. This is provided by oil, coal, natural gas, hydroelectric, and land fill gas. If you add these figures, Ireland's total generating capacity could be 7652 MW.
A few statistics about Ireland are the unemployment rate November 2009 was 12.9 percent and the average residential cost of electricity averaged about 22 cents per kwhr. Both of these numbers were among the highest of all countries in the European Union. Maybe high electricity prices contribute to high unemployment.
Figures 1 and 2 give electric power generation in megawatts as a function of time for January 25, 2010. Figure 1 is for wind power and Figure 2 is total system generation. Similar graphs are shown for other days of operation.
Figure 1. Wind power generated for Ireland for January 25
Figure 2. Total electric power generation for Ireland Jan 25
Figure 1 illustrates the rapid changes in wind power generation that takes place daily in the Irish system. Wind turbines operate during wind speeds from 9 miles per hour up to speeds in the vicinity of 34 miles per hour. The power from a wind turbine is proportional to the cube of the wind speed. So a small change in wind speed can cause significant changes in power output. For this day, the maximum wind power output was 280 MW; although EirGrid claims they have 1260 MW of wind generation connected to their system. Possibly turbines were out of the system or wind speeds were inadequate for maximum power generation.
Total peak demand was 4800 MW, which occurred at 6 p.m. This time is similar to the United States. You can note that peak production of wind power was at 9 p.m., three hours later than peak system demand.
To keep production matched with demand for rapidly changing production with wind turbines takes generators that rapidly change output. Hydroelectric plants and natural gas combustion engines can make these rapid changes. Because hydroelectric power generation is small in the Ireland grid, it is likely load shifts have to be made with natural gas powered combustion engines.
It would be interesting to show measurements of carbon dioxide reductions obtained by using wind turbines. The load following equipment may be of a lower efficiency than would be used if no wind turbines were in the system. This means a greater carbon dioxide output when standby equipement operates. Standby equipment might have to be operating with no power supplied to the grid which contributes to unnecessary carbon dioxide production.
One factor that is never mentioned when discussing wind power is that a considerable amount of standby electricity is necessary for turbines when they are not in operation. The nacelle needs to be heated and de-humidified year round. Controls on the blades have to be powered year round because blade pitch may have to be changed due to excessive winds. These standby demands may be significant, and possibly at times exceed, the output from the wind turbine. Fossil fuels may have to be used to provide standby power.
Large carbon dioxide reductions from use of wind turbines may be fantasies generated by those promoting use of wind turbines. These promoters are manufacturers of wind turbines, wind turbine associations, utilities or others making money because of government subsidies, and U. S. government organizations such as the Department of Energy and its affiliate the National Renewable Energy Laboratory (NREL).