Uniting Europe's Wind Power Supply with a Continental DC Grid
by Jeremy Elton Jacquot, Los Angeles on 07.30.07
Though he may have lost the battle of the currents to George Westinghouse in the 19th century, it looks as though Thomas Edison's direct current (DC) standard may finally be making a comeback. In light of Europe's growing interest in wind power, scientists and entrepreneurs alike are giving DC transmission a second look and are considering using it as the basis for a continent-wide high voltage DC grid.
The reasoning is fairly straightforward: unlike AC transmission, DC suffers low voltage losses over long distances. Incorporating it into a continent-wide power distribution system would thus deal with two of wind power's main downsides: the fact that you can't always get it when you want it and where you want it. Since the wind is bound to always be blowing somewhere, the current generated by wind turbines could be stored and made to flow in one direction or another, depending on each country's energy needs. How then to store all this wind power?
An important component to this continental grid would be the branch to Norway. Since it has a large number of hydroelectric plants, wind energy could be stored in grid-filling quantities and used to pump water up into the reservoirs that power the turbines. If there were to be a large wind drop across Europe — leading to a resulting drop in wind energy production — the water stored in the reservoirs could be unleashed to power the hydroelectric turbines and provide a large source of current that could be transmitted over the grids to sustain the continent's needs for up to 4 weeks. While other transient and long-term energy storage schemes are being considered, Norway's hydroelectric turbines — because of their huge capacity — will likely account for the brunt of it.
Jürgen Schmid, the head of ISET, an alternative energy institute at the University of Kassel in Germany, and one of the lead proponents of this continental grid, estimates that it could supply at least 30% of the power needed in Europe. He envisions them eventually replacing all base load power plants — conventional power plants that provide a continuous and constant flow of power regardless of demand — which would greatly help reduce carbon emissions and pollution.
Several companies in Norway have already begun building high voltage DC lines between Scandinavia, the Netherlands and Germany while Airtricity, an Irish wind power company, has plans to build what it calls a "Supergrid" — which would connect offshore wind farms in the Atlantic Ocean and Irish, North and Baltic seas with consumers in northern Europe. Others believe its potential could be carried over to solar, wind and geothermal power to create a global energy market gathering and transmitting current from one continent to another.
Though certainly promising, whether all these rosy scenarios come to fruition, however, remains yet to be seen.
Via ::The Economist: Where the wind blows (magazine, sub. required)
See also: ::Colossal Magnetic Levitation Wind Turbine Proposed, ::What did the Wind Say to Coal?, ::Innovative Wind Turbine From Australia
Image courtesy of scjody via flickr
Thirsty for more? Check out these related articles:
- New Spanish Wind Power Record: Wind Supplies 43% of Spanish Electric Demand
- Jet Engine Wind Turbine Design Could Halve Wind Power Electricity Costs
- From the Forums: Wind Power Not Benefitting Us!
- China Will Be the Biggest Wind Power Equipment Manufacturer by End of 2009
(for fact check purposes, I don't care about posting)
Are you certain that DC current offers an advantage over AC in transmission? I have heard the opposite. I believe DC is good for a de-centralized system, but suffers current loss over long distances. This is why Edison lost out to Westinghouse in the War of Currents (see wikipedia entry) because Edison's DC system requried a lot of distributed generators and AC could have fewer, larger plants.
DC may be ideal for wind, because of so many distributed generators.
Actually, both you and the post are correct. The long and short of it is that if you can transmit at high voltages you will reduce your resistive losses. The reason AC won the War of the Currents was because it could easily be stepped up to a high voltage, transmitted a long distance, then stepped back down again. DC could not. Nowadays, DC voltages can be stepped up and down (and converted to AC) very efficiently, and DC is often favored over AC for long transmission lines for several fairly technical reasons.
To add to what Alan said, in the past large inefficent motor/generator sets were used to convert AC to DC. Now solid state devices handle this with little loss.
One correction DC can't be stepped up, this would be done using AC and a transformer and then conversion to DC would take place. Kinda the reverse of what happens in a wall wart only we're talking megawatts.
So if everyone had some type of generation system in their home (solar, wind, geothermal, methane collection/burning from composting toilets, etc.) DC might allow for a distributed power grid? I like that.
My understanding is that DC's primary advantage is the fact that higher voltages can be transmitted without detrimental resistance, so effectively, higher throughput can be acheived. I beleive that there is a DC line transmitting large amounts of power from Canada to the US northeast for this reason. The problem is both one of rectification (converting to AC locally) and also one which no one has mentioned yet, which is the propensity of long distance DC lines to act as antennae. . . Solar phenomena have been known to cause large fluctuations in current and have even resulted in serious harm to the grid in the past.
I'm subscribed to The Economist and read this article with great interest. There is one key piece of info that was in that article that is missing in this compacted version of that text which would greatly affect the comments made here by others. That piece of info is, that according to the The Economist article, high voltage AC lines naturally leach electrical energy to the earth and that that is one fundamental reason they must be kept high off the ground. The higher the AC voltage, the more leaching and therefore electrical losses that will occur. The way to counteract this is to raise high voltage lines high away from the ground, and very high voltage lines very high off the ground. DC high voltage has minimal leaching to ground and would not require such high towers. The problem with establishing a Europe-wide grid is that the votages (whether DC or AC) would have to be EXTREMELY high in order to cover such large distnaces with minimal losses. And doing so with AC would be impractical because the towers would need to be impossibly tall to minimize leaching of electricity to earth whereas high voltage DC lines would not have that problem.
A rumor without a leg to stand on will always find some other way to get around. It is not a proplem of high-voltage AC "leaching" to the ground that requires power line towers to be elevated, but one of "arc-over", which is basically just man-made
lightning. When the electrical potential on the power line reaches an arc-over potential, the Electro-Motive-Force (EMF) overcomes the insulating factor of the open air between the powerline and the earth ground reference of the dirt, causing an ionization field to develope between the earth and the powerline, and then
the electricity on the line leaps across this path, just like lightning. So you have to make sure that the powerline is too high for the EMF to "arc to ground". It is negligent at best if the referenced article tries to claim that Direct Current (DC) EMF
does not arc. Of course it does! In fact, the natural lightning of electrical storms is DC. Also, I must debunk the claim that DC voltage drops lessen with
an increase in voltage potential. On the contrary, the voltage drop and the power disipation (which is where the really bad losses occur) grow worse the higher the voltage. Those trying to sell the DC power grid are just intending to crank the voltage so high up, that they will still have usable energy levels at the end of the powerline, despite the massive transmission losses. Ohm's Law rules. It is a fundamental law of the universe. Trying to claim that electrical resistance lessens at higher voltages is like saying that the faster a car travels down the road, the less wind resistance it faces. The skin effect of the wire increases the
effective resistance of the wire the higher the voltage you put on the wire. I wish I time to go into that subject, but I've got to go. Take care, guys.
Engineer John, I think you're missing the point of the high voltage lines. You lose energy by having a lot of electrons moving, in other words by having high amps. So in order to keep the number of moving electrons to a minimum, they put the voltage as high as possible. Less electrons are moving (hence less losses) but the same amount of power is transmitted because each electron has more energy (since it is at a very high voltage). P = I V. You can't do the I, so you do the V.
I know a much contested issue is whether or not there is a correlation between proximity to power lines and adverse health problems such as childhood luekemia. Whether you believe there are real risks or not, can someone tell me if there is equal concern for AC power lines as compared to DC power lines? I have just been informed that a DC powerline connecting the UK to Ireland is going to be buried 1 meter under my street. The company running the project is Eirgrid and I believe the proposed power running through the line will be 500mw. As you might have guessed, I am not familiar with the workings of electricity, however I would like to know if DC powerlines also create possibly harmful EMF's (electric and magnetic fields)?