Why wind power works in Denmark
Posted by Super G on August 31, 2006 - 7:40pm
Topic: Alternative energy
Tags: denmark, wind power [list all tags]
[editor's note, by Super G] The following is a guest post from Cry Wolf.
This post is based on an excellent report titled "Why Wind Power Works in Denmark" by Hugh Sharman, which can be found here.
The main problem with most oceanic and climatic forms of renewable energy—wind, tidal, wave and ocean currents—is that electricity generation is sporadic and may not be linked to the times that power is needed. Hydroelectric power alone provides a means of storing this oceanic/climatic renewable energy for use when it is most needed making Hydro an invaluable source of electricity.
The current absence of a means of storing wind energy leaves electricity grids at the mercy of the weather and critics have long since pointed out that wind energy cannot provide a grid base-load. Furthermore, it cannot be relied upon to provide peak electricity production. So what is the point in having wind energy? It has seemed to me that wind's primary purpose has been to provide politicians with a feel good factor and grounds for claiming green credentials.
Sharman reports wind energy production data for Denmark for the whole of 2003 and shows how shockingly unreliable wind energy production is. But he also shows how the Danes and their Scandinavian neighbours have made wind energy work productively by balancing Danish wind energy output against Norwegian and Swedish Hydro generation and here in lies the main message of this post. But first, a summary of the findings.
Denmark
Denmark lies on the eastern margin of the North Sea where it is quite windy. The population is around 5.5 million and the country produces the highest per capita amount of wind energy in the World. There is 0.88kW installed wind capacity per capita in Denmark compared with 0.18 kW per capita in Germany and 0.01 kW per capita in the UK. Wind supplies 16% of Denmark's electricity.
The Danish wind carpet
Denmark has 5500 wind turbines including two large off-shore wind farms. A total capacity of 2374 MW was installed by the end of 2003. The Danish grid is split in two (there are some large islands) and Sharman's report deals only with the west Danish grid, representing 80% of the total. Crucially, the west Danish grid was already connected to Norwegian, Swedish and German grids before the wind carpet was built.
A fine day at Horns Rev, the World's largest offshore wind farm
Load factor
The load factor of the Danish wind carpet is only 20%. In other words, for every 5 MW of installed capacity the wind carpet on average produced 1 MW during 2003. Information on the cost of installing wind power is given here.
On average 1kW of installed wind power costs $1000. Therefore, to get 1 MW return, 5 MW costing $5million needs to be installed.
Highly variable output
There were 9 occasions in 2003 when the wind carpet produced at > 2000 MW (>85% of installed capacity) but these periods of high output were short lived (Sharman, Figure 8). The output suffers from extreme high amplitude high frequency variance - in other words it is very spiky. "Sometimes the Danish wind carpet produces maximum output when there is little demand. On other occasions it delivers no energy when demand is high". On one day during 2003, the wind carpet actually consumed more energy than it produced.
I find the high variance in output surprising as I'd always assumed that wind in one location would compensate for no wind at another and this should result in some smoothing of output. In Denmark it seems that the wind blows everywhere at once and this may be due to the flat topography and relatively small area. In larger, topographically more variable countries it might be expected that greater smoothing of output will occur.
How the Danish grid is balanced
The west Danish grid is connected to the Norwegian, Swedish and German grids. The inter connectors were built as export lines of Norwegian and Swedish hydroelectric power to Germany but have found a new use in helping to balance the highly variable wind output from Denmark.
Figure 13 (Sharman) shows the hourly output from the Danish wind carpet in December compared with energy exchange over the interconnectors. This shows quite amazingly that essentially all Danish wind power is exported to Norway and Sweden. These countries dynamically balance the interconnected grid using their extensive hydroelectric generating capacity that can be adjusted rapidly to compensate for the highly variable input from Danish wind. In essence, water is conserved in Norway and Sweden when the wind blows in Denmark. This conserved water can be used to produce power when it is needed. This to my mind is a brilliant scheme that essentially provides a means of storing wind power through conserving hydro power.
Energy sinks
Sharman also points out that some of the variance in Danish wind energy output gets sunk into the massive German grid that lies to the South. The variance in the Danish wind supply is only a problem for Denmark because wind energy represents a significant proportion of the total grid supply—16%. Any country wanting to rival the Danish wind model will have to either develop a grid balancing system or develop energy sinks within the grid or both.
A few weeks back some TOD engineers were throwing around ideas about using the batteries of electric cars as sinks for wind energy. This sounded a great idea. Would it also be possible to develop water-heating systems in public buildings to store heat when the wind blows? Would it be possible to use wind energy to actually pump water back into hydro dams using existing pump storage schemes?
Conclusion
Denmark has no indigenous hydroelectric power but has managed to negotiate a power balancing agreement with Scandinavian cousins to make their wind carpet work. Larger countries such as the US and the UK that have extensive hydroelectric capacity must surely manage to engineer a power balancing act between their wind and hydro generators.
Cry Wolf
AKA Euan Mearns
euan dot mearns at btinternet dot com
The concept is called Vehicle to Grid or V2G and several summeries on the concept can be found here:
http://www.udel.edu/V2G/
http://www.vehicletogrid.com/
Also there is a promising Australian invention - Vanadium batteries. However in the usual nature of Australian innovation it is completely ignored here until the inventor finally moves offshore where it is enthusiastically embraced and marketed.
http://tyler.blogware.com/blog/_archives/2006/8/30/2280046.html#comments
http://www.vrbpower.com/
But I don't actually see how it helps at all as a wind sink. You need to charge your car to go to work tomorrow, whether the wind is blowing or not.
Might conceivably be useful for a set of spare batteries?
You'll be charging all night, probably plug back in once you get to work.. so for a great majority of the day, your PHEV's batteries will be working with the system. Be interesting to see if the 'Park and Ride' concept would grow to include plug-in's at the train station parking spaces instead of parking meters, and your net electricity usage is charged or credited accordingly.. Could the parked cars (and electric bikes/mopeds) actually be helping to power the train that takes you on the next step?
If the system was modular, there would be the potential for some truly massive battery systems to be connected together. During non-workday hours, there would be a complementary need to recharge many of them, allowing for a lot of 'sponging', and also a balancing of the disproportionately high daytime demand.
e.g. 50% more than I actually need for my daily commute.
... so if there's a windy night, my battery gets a full charge. And if there's a week without wind, my battery only charges to 50% every night. And I need an override button to charge it to 100% (at a higher price), because I've got a longer trip tomorrow.
Something like that.
This would smooth out demand during the 12 or so hours at night that the car was available for charging, as well as eventually during the day at work, when charging stations were installed in parking garages and at meters, like in Minnesota and Canada for engine heaters.
As battery size grows, the period of time for which the battery can provide smoothing would grow from the daily cycle, to a weekly cycle and more.
Thxs for this post. It has many good ideas. My suggestion is that wind power could also be harnessed to pump seawater behind seaside dams built along the mountainous seashore. Not sure of the environmental effects, but it might be a good way to store energy in areas where there is insufficient freshwater runoff to justify a hydrodam.
Bob Shaw in Phx,Az Are Humans Smarter than Yeast?
However, tide power is intermittent, though predictable... so the pumped-storage aspect would need to be big enough to mask the tidal variation, otherwise you're creating another imbalance problem.
Paradoxical.
The integration of wind power is high on the agenda in Europe. Here you can find the Wind energy industry views. They indicate that in the European grid some 20 % wind can be integrated "without problems" in the EU. Industry wiewpoints, but better than speculation.
http://www.ewea.org/index.php?id=60&no_cache=1&tx_ttnews[tt_news]=43&tx_ttnews[backPid]=1&cHash=f7f7678089
At the bottom links to the main reports
http://www.ewea.org/fileadmin/ewea_documents/documents/publications/grid/051215_Grid_report.pdf
A lot of talk- but also useful technical info.
Regards And1 from Denmark :-)
http://www.dom.com/about/stations/hydro/bath.jsp
Pumped air is limited to ~60% efficiency due to adiabatic heating/coolling.
Wind & hydro are a VERY good match. Hydro can be dam (run-of-river not so good) or pumped storage (ideal).
New Zealand can accept "at least" 35% wind energy because they are half hydro. Once they get close to 35%, they will study the issue more.
An interesting note. Hydro is twice as variable as wind on an annual basis (per speaker at HydroVision). "Wind droughts" are rare.
Except in the form of reduced water consumption in the dams, of course.
New Zealand can accept "at least" 35% wind energy because they are half hydro. Once they get close to 35%, they will study the issue more.
Does that mean that with a wind-hydro balancing system that you can install up to 70% of your hydro capacity as wind?
Note your point about droughts - its just that here in Scotland we've never had any direct experience of drought. Though in Norway, lesser snow falls in recent winters have left many magazines half empty - skiing across those in winter can be interesting with massive tangles of ice blocks along the shores.
Sounds plausible to me. You would also need good transmission linking the whole system.
Regards,
Thomas O. Gray
American Wind Energy Association
www.awea.org
www.ifnotwind.org
Regards,
Thomas O. Gray
American Wind Energy Association
www.awea.org
www.ifnotwind.org
Recently a TOD poster suggested that we need to move from nature's stocks (fossil fuels and uranium) to nature's flows (wind, solar, geothermal).
The challenge is that the current business model of the investor-owned, coop and muni utlities doesn't necessarily lend itself well to a free market. The non-generating utilities (generally smaller munis and coops) need to recover their T&D costs. The large investor owned utilities have an inherent bias towards large, centralized plants and feel threatened by distributed small hydro, wind and other DG technologies so charge high interconnect fees, pay avoided costs rather than time-of-day, market rate pricing and increase the hassle factor for small and medium sized self-generators and independent power producers.
The requirement for ISOs (Independent System Operators) where transmission and distribution is decoupled from generation has been helpful in some markets though the big players are still quite effective in most places in limiting competition.
At this point a market restructuring is needed but the rolling black-outs and sharp price hikes in California has arrested interest in market reform (despite the subsequent disclosures on how much that the disarray was market manipulation by Enron and others).
On a seperate but related note in July 2006 the US DOE and EPA released a comprehensive report "National Action Plan for Energy Efficiency" (see http://www.epa.gov/cleanenergy/actionplan/eeactionplan.htm) that highlights the challenges of utilities planning for and investing in energy efficiency as an alternative to building additional capacity.
http://www.aip.org/tip/INPHFA/vol-9/iss-5/p8.html
Interconnects might be risks from the standpoint of cascading blackouts ... but that looks like a big system in place already for north american electricity trading.
Odd article. The claim is that the grid needs to be managed as a 'single machine".
The Center for Smart Energy (http://www.centerforsmartenergy.com) has several research reports which suggest that the difficulty with the grid is that it is still primarily electro-mechanical in nature which makes it quite difficult to manage. Power plants, substations, transfomers, and other physical components of the "system" lack the industry standard communication, command and control protocols that would make it much simpler and cost-effective to manage a distributed, heterogenous network rather than the "physical grid" the author emphasizes. The US DOE (particularly the Pacific Northwest National Lab) and others are defining what a 21st Smart Grid might look like.
This is not to say that there may be physical constraints and challenges in the T&D grid. It is to suggest that the grid is not a network without standard protocols, sensors, and digital controls that can more effectively manage and map system resources and improve siting and system expansion decisions. Such a Smart Grid would make it easier to monitor and manage a wide range of centralized and decentralized generating assets without requiring a single entity to control generation, T&D and billing to end-users i.e. it would effectively allow the movement from monopoly to market by decoupling generating, transporting and billing for electrons.
What significant maintainance and upgrade work is being done in the north east USA and what major new gridlines are in the pipeline to be built after the 2003 breakdown? Your breakdown were worse then ours and it should have resulted in emergency investments and not the slow ones to be completed 6-9 years after the need became apparant done here.
They are. In those jurisdictions where the networks are privately held note the use of 'eminent domain' to secure rights of way, as well as extensive regulation.
The daily deals are brokered on:
http://www.nordpool.com/
The benefit for hydro power is that you get paid better for day power during weekdays then night power wich means that you close the gates during nighttime and run full power during daytime.
I do not know about the Norwegian hydro power but most hydro power in Sweden were originally state owned, municipiality owned and corporate owned with origin from the pre electrical power use of the water falls. Unfortunately a generation of not so bright economists and CEO:s decided that powerplants were not core business and manny heavy industry corporations and municipialities sold hydro powerplants and shares in nuclear powerplants. In hindsight they sold them very cheap. They buyers were in the end mostly Finlands Fortum and the German E-On and the Swedish state owned Vattenfall.
There is now a cooperation of heavy industries where manny of them sold their powrplants who now are pooling resources to import electricity and build new powerplants they own.
Some is owned by local municipalities and counties, some by the heavy industries (smelters) and the rest by the state-owned power producer Statkraft.
There has been some debate during the recent years over ownership structure:
Many people are accusing Statkraft of Enron-like market manipulations. Statkraft hasn't shut down power plants for maintainance at the worst possible moments, but they have sold off power in the summer such that they cause prices to spike in the winter. The fact that they control something like half the Norwegian electricity production through it's subsidiaries and ownerships in community owned power producers, is viewed as negative for the power market. In 2005 the government ordered it to shed one of its subsidiaries; Trondheim Energiverk. Of course, during the summer of 2005 it became clear that Statkraft was receiving heavy bids from european power companies for this polished gem, which they had acquired on the cheap from the city of Trondheim during the 90s when many communities preferred to invest in the stock market or pay back bonds. The fear that some foreign company like E-ON or Vattenfall should have the highest bid instead of the county-owned Norwegian NTE, caused the new leftwing government to shortstop the deal in the autumn of 2005.
In Norway we also have a special law that says ownership of a hydro-power plant will revert to the state after 100 years. As many power plants are approaching this age, there have been complaints of lack of investment in old power plants.
One company which owns many of these plants, Norsk Hydro, is also the second largest power producer of Norway. Hydro may be a public company, but it's owned 43.8% by the Norwegian state.
As mentioned above, many local communities chose, during the 90s, to sell their stocks in power companies, mainly to Statkraft. Those communities that chose to put their money in the stock markets instead, are trying to put up a brave face as power companies are now raking in profits.
The balancing of wind with hydro is a bit complicated. Since the power bourse (Nordpool) only accepts bids a day in advance, I guess the wind power plants just have to dump their power on the grid and let the grid system operator deal with it. Of course, if a company owns both hydro and wind, they can sell power equal to their wind capacity and crank up their hydro power to replace the wind power that fails to materialize. Special deals between hydro and wind producers could serve the same purpose.
For more information on the Norwegian/Nordic electricity market, the norwegian system operator has more.
As an aside note - use of electric clothers dryers is not allowed in Switzerland during the day.
As I recall, the Swiss generally have drying rooms in the basements of apartment buildings. So a night-only system is pretty easy to set up, and can monitored by vigilant citizens... Even in individual houses, the Swiss are disciplined enough to respect such a restriction.
Hard to imagine it working in any other country, without financial incentives.
Also noted that at an average of 20% of maximum output, you need $1000 worth of installed capacity to produce an average of 200W of power ($1000 per kW of max. capacity). Even without cost allowance for maintainance, this works out at $5 billion per GW - about the size of a large "conventional" coal-fired station. Even though you don't need any fuel thereafter, it makes it look unattractive as long as there is coal to be burnt which is at a reasonable price.
Those also serve who only stand and wait as Milton said.
There is an hierarchy of reserves depending on how fast they can come on line. Steam turbines take the longest to start up from cold, gas turbines are faster and for the fastest response from conventional plant some of the reserve is keep with the turbines turning but not generation power , the `spinning reserve'. This is the most expensive as it consumes some fuel. Dinorwig's outstanding characteristic is that it can go from 0 to 1300MW in 15 seconds from cold. It earns a steady profit standing ready to do this around the clock but only on a few occasions actually doing so.
In the US capacity factor is about 30%.
phil said,
" energy loss problem, think it's something like 5% per 1,000 kilometres, not insubstantial. Maybe this is something that will improve with time though?"
It is already improving and is one of the giant "quite revolutions" underway in the energy industry. The trick is to and power in distrubuted, decentralized, and diversified ways throughout the grid, and make the grid a "live smart grid" instead of "dumb terminal" type grid, as it has historically been. this is the goal of DG or Distributed Generation, sometimes called distributed energy:
www.distributedenergy.com/de.html
By having a network of semil self supporting but still grid connected power generators of all sized mixed into a "smart grid" and networks of "mini-grids" then a variety of power production types (natural gas generators, propane generators, waste gas to methane powered generators, Diesel generators, wind generators, solar and photovoltaic generators, mini-hydropower units, on and on, can be mixed in various sized into the grid making it "super flexible" and diversified in the types of power coming in and the variety of sources they are coming from. This would mean that no kilowatt in particular would have to travel very far before finding it's customer, and the further along the path, the variety of distributed generators would put the power on the grid to service the customers at greater distance. The larger centralized power stations would still be there to do the "baseline" support, and peaking activity, but as more and more distributed unites handle their own peak, the peak loads could come down considerable, to the point that at some future time, the day/night and month to month line would be almost flat with very small "bumps" instead of "peaks".
The other shoe to fall is electric storage. Batteries are improving but still expensive...CAES (Compressed Air Energy Storage) is viable but again, not cheap...flywheel systems may make their breakthrough here, as may fuel cells (both much, much better in a stationary setting than in transportation, where I don't think they will ever find a market, despite the high hopes of the auto fuel cell and flywhell proponents, they have been tried for 30 years in transport and still not delivered).
Some have mentioned the "pumped hydro option:
This is not cheap, but has the advantage of providing water catching areas for irrigation, recreational and nature enhancing lakes, and provisioning drinking water for populations, not a bad trade when you add in the energy storage function as well. Pumped hydro can be integrated to wind as well as using off peak electric grid power to pump the water up, and even further enhance the efficiency.
http://www.electricitystorage.org/tech/technologies_technologies_pumpedhydro.htm
http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
http://www.publications.parliament.uk/pa/ld200304/ldselect/ldsctech/126/12624.htm
however, if we want to build many of them, we need to do so "pre peak". The cost of fossil fuel (Diesel for machines) in construction is already higher than it would have been a few years ago, and the cost of concrete construction due to the natural gas cost, while off the post Katrina peak, is still considerably higher than it would have been a few years ago.
I and some associates once looked at the possibilty of putting 12 to 16 medium sized pumped storage sites down the Ohio River Valley, From Pennsylvania to just above St. Louis MO/Cairo IL, which would have flattened the day to night peak for a fair market area in PA, IL, OH, IN, KY and reduced greenhouse gas emission over years by Billions of tons, plus provided wetlands for wildlife, waterfowl and fish, and irrigation drinking water reserve. But flattening the day night peak would have been the jewel in the crown.
Of course, this is coal country. Do you think anyone would invest in saving a few million tons of coal, as givaway cheap as it has always been. :-(
As Bertold Brecht said, "Such is life."
Folks, I tell you again, the technical problems are NOT the problems.
Roger Conner known to you as ThatsItImout
The Swedish grid were mostly built to transfer cheap hydro power from north to south, interconnect large powerplants, provide for power trading with our neighbours and then there are additional links for redundancy. The main incentive for new investments is to keep the margins large enough for the power trading and increase the redundancy.
The new thing as I see it is small generation units becomming economical to run and better smarts to disconnect parts of or subdivide a grid if there are major faults in it.
Pump storage hydro schemes will surely be expensive, but if this infrastructure already exists, I just wonder if their use could be modified to store wind energy - to at least smooth out some of the short time scale fluctuations.
In the UK, the renewables debate normally revolves around reducing CO2 production. No one is thinking about the possibility that there may not be enough gas to fire the power stations by 2020. At some point national governments will need to exert more influence over the generating and transmission infrastructure companies to ensure that the non-technical problems to which you refer are overcome.