By Dr. Klaus L.E. Kaiser, Canadian Free Press
Alternative energy is in vogue these days. Our politicians are willing to spend megabucks to subsidize wind turbines, their manufacturers, installers, and owners to produce alternative electric power that way. Of course, any manufacturer or vendor will provide you with “generating capacity” numbers, and they sound great. The politicians, journalists, and green lobbyists love them; numbers with megaW of installed or planned new capacities are touted in all kinds of pamphlets and announcements. There is just a little fly in the ointment. The term CAPACITY no longer has the meaning it used to have.
Conventional (coal, gas, nuclear)
When you read about the electricity generating capacity of a coal or natural gas-fired power plant, or that of a nuclear power plant, the term capacity refers to what such a system—if fully functioning—can deliver on a 24 hour – 7 day a week basis. This is widely understood and we expect the electric power we wish to use at any given time to be there—on demand.
Manufacturers and vendors of alternative electric power systems, such as wind turbines, also use the term “generating capacity”, but with an entirely different meaning. What they mean with “capacity” is in reality “NOMINAL CAPACITY”, and that differs substantially from the real life output or the actual power available. The main reason is that the power function depends on the CUBE (not SQUARE) of the wind speed. The table below will demonstrate that for a turbine rated for a maximum 100 km/hr wind speed.
Table. Wind speed versus available power (in kW) as theoretical maximum for a given wind turbine of approximately 1 megaW (1,000 kW) NOMINAL CAPACITY, and Beaufort wind scale definitions.
|Example||Wind speed (km/hour)||Power (kWatt)||Beaufort wind scale|
|F||100||1,000 or zero||storm|
As seen, up to a wind speed of 10 km/hour (examples A and B), the power delivered is negligible, at most 1 kW. In practice, it is zero as there is always some friction to be overcome and so forth (for larger turbines the minimum wind speed is more like 20 km/hr). At the other end of the range (examples F & G), when the wind rises to 100 km/hr or higher, (depending on the specific turbine), which may happen a few times a year in strong storms, the system has to be shut down in order to prevent physical damage. That speed is also called the cutout speed; the energy delivered then is also zero.
At speeds in between, such as in the examples C, D and E, power is generated, but at much less than the maximum or nominal capacity. Even at a wind speed of 50 km/hr the energy available is only 12.5%, and at a wind speed of 75 km/hr (common in many storms, which typically occur a few times per year), the energy is only 42% percent of the nominal capacity. In order to get anywhere near the nominal or plate capacity of the turbine, the wind speed would have to be just below the turbine’s cutout speed all the time, in other words at storm or hurricane speed (example F). Of course – and thankfully so – this is not the case anywhere.
Bigger = Better ?
Some of the newer wind turbines have cutout speeds of 110 to 120 km/hr, rather than the 100 km/hr claimed for earlier models. While one may think that this makes them more productive at any (lower than maximum) speed, in fact, the opposite is true. A turbine with a rated cutout speed of 120 km/hr (hurricane on the Beaufort scale, example G), would only produce approximately 7% of its nominal capacity at a wind speed of 50 km/hr versus 12.5% for one rated at 100 km/hr. But the manufacturers and vendors of wind turbines like to ride the (political) bandwagon of “bigger and better” and, unfortunately, many of the politicians fall for this myth.
The Ontario example
For example, Ontario has currently nine operating “wind farms”, each of which has a number of wind turbines ranging from a few to about a hundred with a combined output capacity of close to 1100 megaW. Their output is continuously measured and these data are available, on an hourly basis on the web site of the Independent Electricity System Operator in Ontario. The data show that, on average, the output of these wind farms is in the order of only 8% of the stated or nominal capacity.
For Ontario to actually get 25% of its total electricity requirement (~25,000 megaW) reliably from wind power, it would require in the order of 100,000 of such 1 megaW turbines. However, even if that number of turbines were to be installed in wind-prone areas, that amount of electricity could not actually be used in Ontario alone. Much of it would have to be sent to other locations to avoid destabilization of the electricity grid during storms.
The Denmark example
Denmark is widely cited as a great example for electricity generation from wind power. Indeed, Denmark creates approximately 20% of its electricity from wind turbines. However, it cannot safely use that amount. In fact, only in the order of 5% of Denmark’s electricity consumption comes from wind. The other part (15% of its total electricity) must be exported to avoid destabilization of the grid. This is possible only because its nearby neighbours (particularly Germany) have much larger electricity needs than Denmark and can absorb that wind generated power into their grids without problem.
Despite all that “free” electricity from wind, the Danes enjoy one of the highest electricity costs in the European Union, approximately double the rate found in most of the other EU countries. In fact, the Chair of Energy Policy in the Danish Parliament called it “a terribly expensive disaster.” Furthermore, in terms of carbon dioxide emissions, electricity from wind, when accounted for in full, produces more CO2 than other energy sources. Denmark’s CO2 emissions rose well over 30% in the year 2006 alone.
Variability = Need for Backup
One important aspect of wind power is the variable nature of the beast. In order to maintain an uninterrupted energy supply when demanded by the consumer, traditional power plants (e.g. coal, etc.) have to be in continuous operation. When alternative power becomes available, they then have to be operating without being able to sell their energy to the grid during that standby period. That in turn, of course, increases substantially the overall costs of their operation. Therefore, the consumer will not just have to pay for the much more expensive wind energy (at this time highly subsidized by taxpayers in most jurisdictions) but will also have to pay for the additional, much higher running costs of the traditional power systems relegated to standby operation when there is a strong wind.
The term “Generating Capacity” as used by the wind power proponents is grossly misleading as it would require steady, uninterrupted storm to hurricane force winds to be achieved on a sustained basis.
The variability of wind creates technical problems which make wind power generated electricity both unreliable and costly.
Electricity generation from wind requires full backup by conventional power generating facilities. That creates additional costs attributable to wind power.
Wind power generated electricity is neither free, nor economical, nor a reliable energy source.