There are few renewable energy policies that do not depend heavily on wind power and wind is certainly at the heart of the most ambitious, the EU’s binding target of sourcing 20% of final energy consumption from renewable resources by 2020. As the EU’s target for transport is half that for energy consumption as a whole, it follows that the power sector will be required to source a proportion of energy from renewables that is much higher than 20%. According to the European Wind Energy Association, the figure is 35%.
Within that, wind will be the largest contributor, accounting for just over one-third of “green” electricity, suggesting that between 11.6-14.3% of the EU’s power will be supplied by wind by 2020, according to the EWEA. This would mean the installation of 180 GW of wind power by 2020, up from 56.535 GW installed in the EU-27 at end-2007, producing about 477 TWh of power. The transport element of the EU plan is also dependent on future scientific advances, for example, that second generation biofuels become commercially available. This uncertainty will put more pressure to achieve in areas that are already within technological reach.
But if these targets seem ambitious, it is also evident that wind capacity is being installed at much higher rates than previously forecast by bodies such as the International Energy Agency. According to Stefan Gsänger, secretary-general of the World Wind Energy Association, worldwide wind capacity had risen to about 120,000 GW by end-2008, an increase of 30% on 2007. According to Platts Power in Europe, wind additions in Europe for the first time in 2008 accounted for more new generation capacity than any other power source, including gas. A study carried out by the Deutsches Windenergie-Institut in 2008 estimated that the annual worldwide installation capacity of the industry would have risen above 100 GW by 2017.
Experience in Europe shows that with the right policy framework, wind capacity can rise fast. And while the “binding” nature of the EU’s targets means little in practice, it is a serious statement of intent. Renewable energy also promises new jobs, making it an attractive sector for policy makers on a counter-recessionary spending spree. Wind would appear to tick all the right boxes in terms of energy, environmental and industrial policy, suggesting, as some non-governmental pressure groups do, that the EU’s targets for wind are in fact not that ambitious and could well be exceeded.
The Desirability of Wind
But just because you can, doesn’t mean you should. Wind power has its critics and they feel that their reservations have been overridden by policy makers whose imaginations have been captured by a green agenda that downplays wind’s limitations. Wind’s intermittency cannot be ignored just because it is the most readily available and domestically attractive technology to hand, they argue.
Any electricity system needs a mix of baseload generation power—which tends to be relatively inflexible in terms of switching on and off—and peaking plants, which are more flexible and, as their name suggests, designed to take advantage of high electricity prices at times of peak demand. Wind falls into neither of these categories because it is essentially unreliable.
Proponents of wind power dislike the negative connotations of the word “unreliable,” pointing out that on average the amount of power supplied by a given capacity of wind turbines is reasonably predictable. But, according to the EWEA, wind turbines produce no electricity at all between 15% and 30% of the time. And, on average, the load factor for onshore turbines is about 30%. This means that over 24 hours, 1 MW of wind capacity would provide about 7.2 MWh of power, but there’s no knowing exactly how much or when until the last minute.
As wind provides neither baseload nor peaking plant it has no impact on reserve capacity. There will always be the possibility that, at some point, no power will be produced at all. This threat falls as more wind capacity is added; some analyses suggest 26 GW of back-up is needed for 100 GW of wind, others that back-up needs range from 60-95%, depending on the make-up and size of the system. But wind’s intermittency ultimately means that a system reserve must remain in place. The system must be set up to accommodate wind, but also to work as if it did not exist.
But if wind turbines add little or no reserve capacity, they do produce power. And the impact they have depends on a range of factors, including when the power is produced, the ability of the system to add and withdraw non-wind capacity and how power is priced.
Imagine two scenarios; peak and trough demand. During lower demand periods, the system is at its least flexible, with power supplied by baseload plants. A surge of wind power may simply result in surplus power production, sending prices towards zero. In effect, it is as if the system has too much baseload generation plant that cannot be turned off quickly enough, either for technical or economic reasons.
The ability to export might provide a key safety valve, but would depend on; first, the physical infrastructure being in place; second, prices falling below the external system’s baseload prices; and, third, the lack of a similar wind surge in the external market, either as a result of different weather patterns or of less wind capacity in that system.
At times of peak demand, the system is at its most flexible because the maximum amount of the most flexible power generation capacity is in use. A wind surge would look as if the system had in effect much more flexible plant than it really does. Prices would be shaved, but underpinned by a greater ability to withdraw peaking capacity.
So, in the low demand period, the impact on peaking plant is negligible—they are not producing power anyway. The impact on baseload plant is principally in terms of price rather than generation displacement and therefore would not necessarily result in carbon emissions being avoided. Prices react as the ability to withdraw capacity is low.
In the high demand period, baseload plants again suffer from lower prices when the wind blows. Peaking plants experience either lower prices or generate for shorter periods. This suggests that the principle result would be for wind to displace peaking plant, i.e. gas rather than more carbon-intensive coal or low-carbon nuclear.
The thorny issue of subsidies aside, adding an intermittent energy source would act to reduce prices overall as wind adds power but does not add reserve capacity. In so doing, it increases redundancy in peaking plant and reduces the profits of baseload generation; potentially good for consumers but bad for investment in non-intermittent sources of power, and presenting the risk of a decline in reserve capacity.
Back-up Not Required
The EWEA argues that “because of the way the electricity network is planned, there is no need to back up every megawatt of wind energy with a megawatt of fossil fuel or other power. All networks have enough spare capacity available to deal with disconnections, breakdowns and sudden surges in demand.”
That argument is fine, but only because it assumes that sufficient reserve capacity and flexibility already exists from non-intermittent sources. However, if wind energy is built to meet growth in energy demand it implies a decline in reserve capacity. Wind can be added to a system if demand growth is static or if non-intermittent sources also grow with demand. The amount of “back-up” capacity is related to demand growth not to the amount of wind added to the system.
Take the argument to its extreme. In a system with no wind power, adequate reserve capacity and no demand growth, any proportion of wind can be introduced with no need for any additional fossil fuel powered generation. At 100% wind penetration, the non-wind plant would still be needed for low or zero wind days. However, peaking plant would be used much less and baseload plant would see sustained periods of potentially below cost prices—a particular nightmare for the nuclear industry.
As such, the proportion of wind that can be incorporated into a system is both an engineering challenge and an economic one. The conundrum that wind poses is not just technical i.e. organizing the electricity grid in such a way as to cope with increasingly large rises and falls in supply from multiple and decentralized sources, although this too is a significant challenge. It lies in the fact that wind does not directly displace fossil fuel generating capacity, but will make this capacity less profitable to maintain.
There are a number of ways in which wind’s intermittency might be mitigated. The organization of electricity systems is being rethought to incorporate decentralized, diffused and intermittent sources of energy. Demand response programs are aimed at shaving off peaks in demand, but also might be seen as tools in responding to sudden losses of wind power. Any innovation that increases flexibility within the system should enable the accommodation of higher proportions of intermittent power sources.
The problem of wind producing surplus power when it is not wanted may find a solution in the form of electric cars. The idea, being pioneered in Copenhagen, is that surplus wind power generated at night would be used to power electric plug-in cars for urban transport. Copenhagen is the perfect place to try this, given Denmark’s 20% penetration of wind in the electricity system, the highest in the world, the inflexibility of its (highly efficient) baseload coal-fired CHP systems, and the fact that it is very flat.
It is also a move that could be very bankable in terms of meeting the EU’s renewable energy targets. In the EU’s renewable energy package, it says “the amount of renewable electricity used by electric road vehicles is to be considered to be 2.5 times the energy content of the renewable electricity input, in recognition of their greater efficiency.” It is not clear what measure of efficiency is being used here (perhaps an accounting one).
However, the use of plug-in electric vehicles would create a relatively constant and inelastic demand load within a specific time period, to be satisfied by an intermittent supply. In practice, although it would clearly displace transport fuels, it would mean increased coal and gas burn at night when the wind wasn’t blowing, or vehicle owners would find themselves with a flat battery in the morning.
Proponents also argue that if the power wasn’t used by the car, it could be returned to the grid at peak demand times. This suggests that plug-in electric vehicle manufacturers have found the holy grail of the electricity industry—the efficient storage and retrieval of power. It is more likely that they have not and that the renewable energy returnable to the grid after having been transmitted from wind turbine to car battery is not substantial. However, the displacement of transport fuel with electricity otherwise priced close to zero would be significant.
Efficient storage is a technological advance that could transform wind’s contribution to an electricity system by ironing out the troughs and peaks of power production, effectively neutralizing its intermittency. It could turn wind from an intermittent power source into peaking power plant that makes a real contribution to reserve capacity. There are many experiments taking place in this field, some of which are promising, but (with the exception of pump storage hydro) commercially viable projects on a large-scale do not appear to be on the immediate horizon. But as wind capacity increases, the impetus to make this breakthrough will rise, and the future impact it would have, if it occurs, will be all the greater.
As mentioned, exports could prove a major safety value for intermittent power sources, enabling them to find new sources of demand when there is a surplus of power and acting as additional reserve capacity when the wind fails. Denmark’s capacity to import and export power as a proportion of total system capacity is just as impressive as the world-beating penetration of wind power within its system. But even so, it has its limitations in that excess power occurs when demand is low in external markets, markets that as yet do not have the same level of wind penetration as Denmark.
In the 2nd Strategic Review of the EU’s Energy Security and Solidarity Action Plan, great emphasis was placed on major infrastructural plans that would benefit wind integration. These include the Baltic interconnection plan, completion of a Mediterranean energy ring, the development of North-South electricity interconnections within Central and South-East Europe, and most significantly the development of a blueprint for a North Sea offshore grid, interconnecting national electricity grids and plugging in planned offshore wind projects.
All of these are major projects, requiring a high degree of international cooperation, planning and capital. And international interconnectors can be notoriously difficult to get built; it may well be to the North Sea offshore grid’s advantage that it is indeed offshore. But assuming (optimistically) that they get built within the required timeframe, they should promote competition and improve security of supply, as any available capacity on one national system can be put at the disposal of another, subject to the restrictions of the interconnection.
But the North Sea offshore grid goes a step further than an international interconnection because it implies multiple connections with an added common power source through linked offshore wind farms, potentially serving the UK, French, Dutch, Belgian, German, Danish and Nordic markets. The grid would be more likely to produce some power all of the time. According to the UK Meteorological Office all areas of the North Sea are usually affected by the same weather systems, typically Atlantic depressions from the west, but it is fairly rare for calm to descend across the whole of the North Sea at any one time.
That suggests that offshore wind capacity tied into a North Sea grid would start to provide power that could be depended upon, albeit never quite with 100% certainty. However, that “dependable” power would only be a fraction of the capacity of the total offshore system, and would be split between all the markets the grid would serve. Moreover, raising each national market’s exposure to wind might negate the advantages of the export/import facility. The most common experience could well be that they all experience similar patterns of rises and falls in wind power.
A tried and tested form of storage might prove more reliable. According to Swiss parliamentarian and economist Dr. Rudolph Rechsteiner, Swiss hydro reservoirs are already being adapted to create a system that provides storage capacity.
Swiss hydro has historically been developed on the basis of huge storage volumes released in one season to meet peak seasonal demand. Investment is now taking place to install pump storage so transfers can take place once a week rather than once a year.
Swiss hydro resources could provide sufficient storage to manage all of Switzerland and Germany’s power, and there are at least two dozen possible pump storage sites in the Swiss Alps and 12 in Germany. At the moment, pump storage in Switzerland is absorbing excess baseload nuclear power and releasing the power at peak times into the German market.
Retaining Reserve Capacity
The potential problems of a high penetration of wind power are being downplayed by European policy makers grateful for a domestically produced renewable technology. Although the target 2020 proportion for wind as a percentage of total electricity generation is not that large, 12%, this average is likely to see large differences between EU states. And while wind’s intermittency is likely to be ameliorated over time, the impact on prices of a growing proportion of wind in the EU energy system may prove more immediately challenging than the technical difficulties that a higher penetration of wind poses.
The issue for the producers of power from fossil fuels (and nuclear) and for policy makers is that as the penetration of wind rises, they are likely to see a material effect on prices, while wind turbine income is protected by feed-in tariffs and the like. This is a commercial problem for power generators, but also for the wider system, as in all likelihood fossil fuel plant will still be needed for reserve capacity. It appears that the installation of wind capacity is racing ahead of investment in the infrastructure required to manage that capacity reliably. Taken to its logical long-term conclusion, in this scenario, the only companies eventually able to manage such infrequently used reserve assets commercially, will be the wind producers (or aggregators) themselves.
Ross McCracken, Editor, Platts Energy Economist
The Energy Spectator: “The Unbearable Lightness of Wind”
By William Tucker on 4.21.09
It’s a great title but I won’t take credit for it. Instead, it sits atop a marvelous article by Ross McCracken, an energy economist, in this month’s issue of Insight, the energy journal published by Platts.
Like anybody who understands electricity, McCracken is both slightly provoked and slightly alarmed by the headlong rush into wind power in Europe and America. “Wind power has its critics and they feel that their reservation have been overridden by policy makers whose imagination have been captured by a green agenda that downplays wind’s limitations,” says McCracken judiciously.
The major limitation, of course, is wind’s intermittency – its lack of “dispatchability.” Quite simply, you can never count on it. You can’t even predict it from hour to hour with 100 percent accuracy and the windiest sites can go calm for days. On a national electrical grid, where supply and demand must be kept within 5 percent or each other in order to maintain voltage balances, this becomes very disruptive.
Despite these misgivings, political momentum is pushing ahead with wind at full tilt. Windmill manufacturers added 8,000 new megawatts (MW) to America’s capacity in 2008, doubling the previous year’s output and lifting total capacity to 21,000 MW – the equivalent of 21 conventional coal or nuclear plants. In Europe, windmills were last year’s biggest bloc of new generating capacity, 42 percent. Worldwide, wind’s overall capacity increased 30 percent in 2008.
All this is being driven entirely by government mandates and subsidies. In America, wind gets a 1.8-cents-per-kilowatt-hour federal tax credit – which would cover almost the entire fuel-and-operating costs of both coal and nuclear. The European Union now has a mandate to get 20 percent of its energy from “renewable” sources by 2020. In American, more than half the 50 states have adopted similar laws and a national “renewable portfolio standard” is in the Waxman-Markey energy bill now before Congress. Waiting in the wings is a European-style “feed-in tariff,” which simply orders the utilities to buy so-called renewable electricity at above-market prices.
Many commentators have warned what this is going to do to the reliability of the electrical grid. What’s different about McCracken’s analysis is that he shows where this is all going to lead economically:
The conundrum that wind poses is not just technical [i.e., its intermittency.] It lies in the fact that wind does not directly displace fossil fuel generating capacity, but will make this capacity less profitable to maintain.
The utilities’ generating capacity, as McCracken points out, generally falls into two categories – base load and peaking. Base load runs day-and-night, week after week, to meet the underlying demand. It is almost universally provided by coal plants, which run for weeks at a time before shutting down for maintenance, and nuclear reactors, which can go almost two years between refueling. Peak loads, on the other hand, are generally met with natural gas turbines, which do not boil water and can be started and stopped almost instantaneously.
Unfortunately, as McCracken notes, wind falls into neither category. “As wind provides neither baseload nor peaking plant it has no impact on reserve capacity,” he writes.
In so doing, it increases redundancy in peaking plant and reduces the profits of baseload generation; potentially good for consumers but bad for investment in non-intermittent sources of power, and presenting the risk of a decline in reserve capacity. … [P]eaking plants would be used much less and baseload plant would see sustained periods of potential below cost prices – a particular nightmare for the nuclear industry.
In other words, thanks to government mandates and subsidies, wind will be there to throw power onto the market any time the wind blows. This will not replace base load plants but will only drive down prices, cutting into their revenues. Nonetheless, base-load nuclear plants will have to remain in operation, both because they will be needed as back-ups in case the wind doesn’t blow or – in the case of nuclear – because it doesn’t make sense to keep stopping and starting a plant that runs best for two years at a time.
And so coal and nuclear will become less profitable. Existing plants will be caught in a trap but new construction will be discouraged entirely. Already the British Nuclear Group is complaining that it can’t build any new reactors if they have to compete against subsidized wind farms. Environmentalists are turning handsprings, claiming joyfully that wind is finally replacing nuclear. But what it actually happening is that no one is going to build the plants needed to back up wind’s unreliability.
The one type of generating capacity likely to expand will be natural gas turbines, by far the most expensive way of generating electricity. Gas turbines are jet engines bolted to the ground. They do not boil water but use the gas exhausts to drive the turbines. They are cheap to build but insanely expensive to operate, since the fuel makes up 90 percent of their costs. (Coal is 50 percent and nuclear only 10 percent.) The major manufacturers – GE, Siemens, and Toshiba – are already marketing gas turbines as the “natural companion to wind.” Rather than heading into an “era of renewable energy,” we are headed into an era of natural gas. California, which has been at this for almost 30 years, gets 40 percent of its electricity from natural gas, twice the national average.
Our growing investment in wind, therefore, promises two things – more expensive electricity and declining reserve capacity, especially if electrical demand continues to grow. By coincidence, that’s exactly the path trodden by California on the way to the Great Electrical Shortage of 2000. Or maybe it isn’t a coincidence at all. Maybe we’re just traveling down the same road, this time on a national scale.
William Tucker is most recently the author of the new book Terrestrial Energy: How Nuclear Power Will Lead the Green Revolution and End America’s Long Energy Odyssey (Bartleby Press).
Always greener: More on “renewable” energy
Posted by Craig Morris at Wednesday, April 22, 2009
Yet another article that demonstrates how so-called “renewable” energy cannot possibly be renewable has come to my attention. The American Spectator has published a review of an article at Insight, an energy website. I’ll focus on the American Spectator.
The bone of contention is all the money we are throwing at wind energy, which as “anybody who understands electricity” (like me) knows only causes problems on the grid. As the article explains:
The major limitation, of course, is wind’s intermittency – its lack of “dispatchability.” Quite simply, you can never count on it. You can’t even predict it from hour to hour with 100 percent accuracy.
I’m glad somebody finally had the guts to call a spade a spade. I have been in Germany since 1992, and I can tell you that people over here are suffering greatly from all of this wind power. In fact, back in June of 2008, the situation in Germany had gotten so bad that the German Environmental Ministry published its final report on “Improved grid integration of wind turbines” (here is the website in German). According to the report, wind turbines now have to stay on the grid when the grid is destabilized and provide more “reactive power” – essentially, the turbines have to help make sure that the phases of alternating current remain in pure sine waves so that the grid does not lose power or cause damage to electrical equipment by providing electricity outside of the defined range (see, I told you I understood electricity).
Until recently, wind turbines and solar panels both had to automatically disconnect from the grid completely whenever the grid became destabilized – after all, these so-called “electricity generators” are not dispatchable – but it turns out that they can indeed help stabilize the grid, though only at the cost of lower “real power output”, which is the wattage that turbines and solar power owners get paid for. In other words, they stabilize the grid in the same way that a central power plant does. Because wind turbines make up such a big chunk of Germany’s power supply, they have to help stabilize the grid first, but in a couple of years German law will also force solar arrays of a certain size to stay on the grid and stabilize the flow of electricity when the going gets rough.
That’s the price you pay for being a major electricity producer.
The German Association of Grid Operators has published some pretty harsh statistics showing what the effect is of wind power on grid reliability.
The first chart is from this report, which is a few years old, but it is unfortunately the most recent comparative study that this organization has produced. For each country (click on the picture to enlarge it), there are two bars: the left one is excluding “acts of God/force majeure”; the right one, including. As anyone who understands electricity can see, the number of minutes of power outages over the year on the average goes hand-in-hand with wind production. So Germany actually fares pretty well at around 20 or 30 minutes of outages per year compared to countries like France, Great Britain, Italy, and Spain, which have far more installed wind turbines.
The next chart shows the trend in Germany, albeit for just two years – 2004 and 2005. While you might think that minutes of power outages are actually decreasing as more wind turbines are installed, the latest information available (for 2006) makes the whole issue of the more problematic, as our third chart from this report published in the fall of 2007 shows.
Here, we can see clearly that Germany once again rose above 20 minutes of outages on the average in 2006. Unfortunately, I was not able to come up with a nice colorful chart for the number of minutes of power outages in the US, but according to this report the Electric Power Research Institute puts the figure for the US at 214 minutes. Clearly, Americans know a lot more about electricity than Germans. About 10 times as much, in fact.
While there is no report on power outages in 2007, the German Association of Grid Operators does have the fourth chart in our blog entry on its website. Once again, Germany remains at the bottom of the pack in terms of the number of minutes without power. As you can see, the number of minutes of power outages not caused by force majeure (the ones at least potentially related to wind power) dropped back down a bit closer to 20 minutes on average for the year, but the overall number of minutes skyrocketed because a major storm called Kyrill blew across northern Europe that January, causing five billion euros in damage in Germany alone. In each of those years from 2004 to 2007, wind power grew by more than 10 percent on the average. Clearly, wind is wreaking havoc on the German grid.
Finally, I’d like to come back to the point about “You can’t even predict [wind] from hour to hour with 100 percent accuracy.” This is a crucial point, and I’m really glad that it has been brought up. The matter is actually much worse than the author suggests. It seems that so-called “wind forecasting companies” have given up trying to predict wind from hour to hour with 100 percent accuracy. This company unabashedly writes:
EuroWind provides you with accurate 8-day forecasts of the wind- and solar power generation for any country, region, supply area, or wind farm in Europe, the USA, or Canada.
They are not even shooting for hour-to-hour forecasts. These other guys [EWC] offer a five-day forecast. Would somebody please tell these people we want hour-by-hour forecasts, not eight days and five days?
Of course, neither of these companies put their accuracy into a specific percentage, but we know it’s not 100 percent. But other media reports provide a fuller picture, such as this one from 2007 on Germany’s ISET in Kassel:
Windgeschwindigkeit 12 Meter pro Sekunde, Windrichtung West. Das Rechenmodell nutzt diese Daten und zeigt, wie der Wind morgen sein wird. Kilowatt-genau. Für jede einzelne Viertelstunde – einen Tag im Voraus.
That translates as: “Wind velocity 12 meters per second, direction west. The software uses this data and shows what the wind will be like tomorrow. Down to the kilowatt. For each quarter hour – a day in advance.”
As anyone who understands electricity can see, the companies continue to miss the mark. They either provide forecasts for the next eight days, five days, or for every quarter hour for tomorrow accurate down to the kilowatt, but they do not provide hour-by-hour forecasts that are 100 percent accurate. 99 percent maybe, but not 100 percent.
Of course, conventional power plants of all types are 100 percent accurate. They never break down, there are never any unplanned repairs or maintenance work, and there is absolutely no need for backup power plants (= “reserve capacity”). We have always had exactly the generating capacity installed that we need to meet peak demand and not a megawatt more – at least, not until all of these wind turbines started going up.
In closing, I think the American Spectator’s ultimate point is well taken:
In other words, thanks to government mandates and subsidies, wind will be there to throw power onto the market any time the wind blows. This will not replace base load plants but will only drive down prices, cutting into their revenues. … And so coal and nuclear will become less profitable.
There you have it: wind will drive down the price of electricity. Of course, coal and nuclear have never been subsidized, and no government funding is going to the coal sector for its R&D into carbon sequestration and storage; why on earth would the coal sector need government support anyway after 150 years of profitability? But the author’s other point should also be heeded. The more renewables we have, the more we will have to run our conventional power plants below capacity, and that will cut into the profit margins of utilities. In my book (see the column to the right), I propose a simple solution based on the German model: pay them. Have some accountants calculate the difference, pass it by the grid regulators, and pass the extra costs onto consumers. That approach works quite well in Germany, where government officials are competent and the business world does not cook its books. I don’t see any reason why it wouldn’t work in the US.
The alternative, of course, is also attractive – at least as seen from Germany. America, do not throw all of this money at wind power. Wait until conventional, reliable sources of energy – such as gas, nuclear, and coal – become scarcer and hence more expensive, and wait until the price of wind power has come down. Germany and a few other European countries will be happy to sell you these products when you are caught in a pinch somewhere between skyrocketing fuel prices and a lack of domestic renewable manufacturing industry. Just stick to iPods and Segways, ok? Let Europe do the unnecessary stuff.
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