Wednesday, 18 November 2015

Wind Energy is NOT the same as Conventional Energy

A response to American Wind Association Blog :

Wall Street data: successful PTC cuts wind’s costs, job not done

It is a commonly held belief that wind energy is the same as energy from other sources. But this is not the case. Take this article for example :

Say you deposit $20 in the ATM near your office. A short time later, you withdraw it from the ATM near your house. You now have a different bill than the one you deposited, but that’s irrelevant; you still have $20. 

This aspect of the banking system is analogous to how the electric power system works: it aggregates all sources of electricity supply and demand over a large geographic area, allowing one to add wind energy in one area and use an equivalent amount of electricity somewhere else on the grid. 

Just as it would be impossible and pointless to insist that the $20 bill you withdrew in the banking example be the same one you had deposited earlier, it would be impossible and pointless to require an electricity user to specify the exact power plant they receive energy from.

Wind energy is not dispatchable. Conventional power stations provide dispatchable power. You can dispatch up a power station when there is extra demand for electricity. You cannot dispatch up a wind farm. You can dispatch down a wind farm but this is obviously not as useful as dispatching up. For this reason, you cannot build a grid around wind energy, but you can do with conventional generation. So 1MW generated by conventional sources is many times more useful than the 1MW generated from wind sources (In addition, the 1MW from the former provides synchronous power crucial to the stable running of the grid).

So to use the above example, you deposit 20 Lira and then later you take out $20. No country in the world could or would allow such transactions to take place. But this is exactly what happens with wind energy.

The integrated nature of the grid allows companies who wish to use wind energy to add it where it is most cost-effective to do so, even if the location of their primary demand center is in an area that is less suitable for wind generation. Many large companies are now using this strategy to increase the percentage of clean energy on the grid, adding supply in one area and using an equivalent amount of electricity in another. Purchasing wind energy in this way allows these companies to meet their sustainability goals while saving money.

The wind energy provided by a company may be of little use to the grid. Most of its power may occur when demand is low. The result is an over-supply of power when what is required is supply that can match demand and effectively replace older supply. Wind energy can never do that and it's capacity credit diminishes with each MW added.

So it may make these companies and their customers feel happy but actually there is little benefit added. Fast acting plant must be built to back up wind once capacity reaches high levels thereby negating any benefits due to the wind.

Another myth is perpetuated in the same article :

American wind power opponents also claim that because wind is a variable resource, it can’t generate electricity at 100 percent of capacity. But the truth is that no energy source runs at 100 percent capacity 24/7, 365 days a year; and wind’s percentage is actually comparable to the average hydroelectric or natural gas-fired power plant’s output factor.

Powering a data center on a single fossil or nuclear plant would not work either, because those plants experience unexpected shutdowns or maintenance outages about 10 percent of the time (and often cannot or do not run flat-out the rest of the time). Nuclear and most fossil plants also cannot easily change their output in response to changing electricity demand, so they alone couldn’t meet the facility’s needs for this reason as well. In almost all cases a data center or factory is a poor place to build a power plant of any type, whether it be fossil, nuclear, or wind, as most sites lack the fuel source and other services needed for operation.

First of all, data centres do build power generation units onsite. Indeed, the Apple centre in Galway will have large reserves of diesel generators which can quickly switch on in the event of loss of power.

The writer mistakes intermittency with outages. A power station requires back up in the event of an outage. Outages occur between 10 and 15% of the time. Somewhat ironically, outages occur more often in a system with large amounts of intermittent energy, like wind, due to the increased cycling that generators are forced to do with wind on the system. Hence, the need for more fast acting, but inefficient generators to act as back up.

Wind energy is intermittent but can also suffer from outages. A recent problem that occurs in larger turbines is that of axial cracking in bearings which has not been solved. There are other technical problems, particularly with larger turbines. When these break down, that's an outage, the same as when a power station breaks down. But a wind turbine's fuel source is intermittent, hence it's output varies with the weather. This means when a turbine is fully functioning, it still can't be depended on to cook the turkey. This is not a problem for conventional generators unless there is a fuel shortage, which is not a problem for the foreseeable future.

And no, storage does not solve this problem !


  1. I do not think I can add anything to improve on this explanation. The only question is how can governments be so stupid to believe otherwise?

  2. If you take the Irish electrical load at 4.00am on 19 Nov 2015 as a typical all-island minimum, Ireland needs at least 3000MW at all times. This is currently spinning reserve less 216MW for the hydro stations of Ardnacrusha, Liffey, Erne and Lee, and 292MW of pumped storage at Turlough Hill.
    A net value of 2500MW of spinning reserve that various schemes propose converting to storage. We could, if we can find sufficient mountains in Ireland, install 10 more Turlough Hills. The only snag is that Turlough hill only has enough water storage to last 6 hours. To achieve 2 days minimum consumption storage would take 2 x 4 x 10 = 80 more Turlough Hills of storage. At maximum consumption we would need 160 more Turlough Hills. For 2 days.
    High pressure compressed air storage is under development in Larne. Like pumped storage, the compressed air is released to generate electricity when needed. The Larne facility will generate up to 330MW of power for periods of up to 6 hours. It is an EU "Project of Common Interest". It is almost identical to Turlough Hill in terms of capacity.
    What about storing energy in people's houses by charging batteries? Great idea, the electricity is stored at the point of use, and the householder pays for the storage. A real win-win? Well, yes and no - the average house uses 10kWh/day, excluding heating (check your last electricity bill). The Tesla Powerwall (due 2016) will store 10kWh, last 10 years and cost around €3500 plus installation plus smart meter.
    That is (ignoring interest) an annualised overhead of €350 per year to keep you going for a day. After that, get out the eco-friendly candles. Water charges, how are ye!

  3. I suspect that the nature of electricity (it can't be stored in a bag) has always been a source of mystique, dreams, magic, sorcery and titillation to brain cells which evolved to to spear a woolly mammoth. If you push enthusiasts of renewable energy to justify their beliefs you will soon find that their struggle is not coming accepting renewables are a scam and don't work, it is that they cannot admit they themselves were so easily fooled, If a person cannot accept they were fooled to day, they are hardly going to accept they were fooled 3 years ago. If they were smart they would accept it, because they were lied to by government, vested interests and the media