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neilzero
2010-May-12, 07:49 AM
~ The following is from the Guardian in The UK. My comments are enclosed by~ By autumn, the nine governments involved Germany, France, Belgium, the Netherlands, Luxembourg, Denmark, Sweden and Ireland and the UK hope to have a plan to begin building a high-voltage direct current network ~USA needs similar HVDC power lines to connect the West Texas wind corridor = World's best to the East and West coast where most of the electricity customers live~ within the next decade. It will be an important step in achieving the European Union's pledge that, by 2020, 20% of its energy will come from renewable sources.

More than 100GW of offshore wind projects are under development in Europe, around 10% of the EU's electricity demand, and equivalent to about 100 large coal-fired plants. The surge in wind power means the continent's grid needs to be adapted.

If you have additional capacity, which you will do within these lines, it will allow power trading between countries and that improves EU competitiveness," said Wilkes.

Producing electricity either through photovoltaic cells, or by concentrating the sun's heat to boil water and drive turbines with marine, geothermal and wind projects elsewhere on the continent. Scientists at the IE have estimated it would require the capture of just 0.3% of the light falling on the Sahara and the deserts of the Middle East to meet all Europe's energy needs.

In this grid, electricity would be transmitted along high voltage direct current cables. These are more expensive than traditional alternating-current cables, but they lose less energy over long distances.
~Several thousand miles of HVDC =high voltage direct current power lines are already operational, so the technology is ready. Let's do it. Neil~

NEOWatcher
2010-May-12, 12:33 PM
~ The following is from the Guardian in The UK...
Do you have a link?

Scientists at the IE have estimated it would require the capture of just 0.3% of the light falling on the Sahara and the deserts of the Middle East to meet all Europe's energy needs.
Why those places? And why choose such a large area of comparison just to give such a small percentage?
It's hard to picture the sizes of those places to begin with.
Surely there's not more or less light falling on those places than other mid latitude areas.

Either they actually plan on putting this stuff there, or they just picked an area that doesn't sound like it will agitate the NIMBYs.

mugaliens
2010-May-12, 06:45 PM
In this grid, electricity would be transmitted along high voltage direct current cables. These are more expensive than traditional alternating-current cables, but they lose less energy over long distances.

Partially true. "The first commercial electric power transmission (developed by Thomas Edison in the late nineteenth century) used direct current. Because of the advantage of alternating current over direct current in transforming and transmission, electric power distribution today is nearly all alternating current." - Source (http://en.wikipedia.org/wiki/Direct_current)

Although the line loss due to simple impedance is the same whether you're using AC or DC, AC transmission has an additional loss due to the skin effect (http://en.wikipedia.org/wiki/Skin_effect), caused by eddy currents. "However, total losses in systems using high-voltage transmission and transformers to reduce the voltage are very much lower than DC transmission at working voltage." - Source (http://en.wikipedia.org/wiki/War_of_Currents#Transmission_loss)

Much of the misinformation favoring DC over AC stems from Thomas Edison's flagrantly fraudulent campaign against Westinghouse's push for AC.

The only two real advantages of HVDC are a higher power rating for a given line and the lack of a need to synchronize frequencies. And yes, over long distances, particularly in buried or underwater cables, it's cheaper.

tlbs101
2010-May-12, 08:07 PM
~In this grid, electricity would be transmitted along high voltage direct current cables. These are more expensive than traditional alternating-current cables, but they lose less energy over long distances.
~Several thousand miles of HVDC =high voltage direct current power lines are already operational, so the technology is ready. Let's do it. Neil~

Depending on the transmission voltage, the load, the terrain (dictating tower size and shape), and a couple of other minor factors, there is a well defined and calculable point of distance, at which DC transmission is cheaper than AC. One example of this: from the Hoover dam hydroelectric plant to Los Angeles, DC transmission is cheaper than AC transmission. From Hoover dam to, say, Barstow, CA. it is cheaper to transmit AC. The "break even" point is somewhere in between.

.

jj_0001
2010-May-13, 11:05 PM
The only two real advantages of HVDC are a higher power rating for a given line and the lack of a need to synchronize frequencies. And yes, over long distances, particularly in buried or underwater cables, it's cheaper.

Well, the lack of need for network stability means that there is substantially less loss. The power plant I worked at (as a summer employee may years ago) in Niles, Ohio, spent almost all of its 250 megawatts keeping the Lake Erie Loop from going unstable.

And, let's not forget radiation loss, either, transmission lines of any length do act as antennae, and do radiate a measurable amount of power off into space. I've heard conflicting numbers, annoyingly, but the conflict was in "how bad" rather than "is it a problem at all".

neilzero
2010-May-14, 02:14 AM
Hi jj: Yes, merging power lines need to be approximately phase locked. Does significant error produce traveling waves on both power lines = the customers voltage rises and falls several times per second = flicker? Slower changes in voltage can be corrected by changing taps on transformers, but each tap change sends a voltage transient down the power line and up the power line. Where are the several hundred megawatts not dissipated in customers loads dissipated? In the big alternators does not seem likely, but perhaps the big alternators need to cut back to half power or less frequently to avoid even worse voltage transients. Can you explain in more detail?
Can't we measure the 60 hertz rf in LEO = low Earth orbit to get a handle on the percent of the power that is radiated as 60 hertz photons?
tlbs, and mugaliens' last paragraph seem to be correct, Neil

neilzero
2010-May-14, 02:42 AM
Hi NEOWatcher: I pasted all the Guardian text about HVDC. Sorry I don't have link, but wikepedia has a good article with the title HVDC. The Sierra and the deserts of the Middle East are on or close to the equator, so temperate deserts = middle latitudes = Europe and The USA have less solar energy with rare exceptions. These Equatorial deserts have political problems so a large area is mentioned in hopes that a small portion will become practical by installation time. The Ecuador highlands may be even better in the Western Hemisphere, but the HVDC powerline would need to run though several unstable countries. New Mexico is likely better than any location in Western Europe North of the Mediterranean ocean. Still better in the USA is the wind corridor, which is thought to be the best location on our planet for wind turbines. Neil

neilzero
2010-May-14, 03:10 AM
Hi Mugalliens: What you typed was true a century ago, when there was no practical way to produce very high voltage DC, nor to convert million volts DC to perhaps 240 volts to use in our homes. Since about 1995 the conversions have become even less loss than transformers and the costs are still falling, so high voltage DC is competitive for distances over about 500 kilometers, sometimes much less. Some HVDC power lines have operated for more than a decade between USA and Canada, and in Europe.
We can even convert million volt DC to 240 volts AC (or other voltages) with many inverters in series at not much more loss than transformers.

neilzero
2010-May-14, 03:33 AM
We should do a pilot program of homes and businesses powered by DC instead of AC. It is especially advantageous for using electric and hybrid electric car batteries and home battery banks to smooth peaks and dips in the grid voltage. Inverters can provide ac for the rare device that is impractical for DC. Neil

mugaliens
2010-May-14, 07:27 AM
Inverters can provide ac for the rare device that is impractical for DC. Neil

You mean the "rare" device such as all electrical and electronic appliances in my home other than five incandescent light bulbs? Who'll pay for my new devices? You?

hair dryer
laptop
monitor
stereo
phone base
phone recharger
cell phone charger
camera battery charger
stereo
portable hard drive 1
portable hard drive 2
fridge
washer
dryer
microwave oven
air purifier
power drill
table saw
circular saw
jigsaw
battery charger
juicer
blender
mixer
hand mixer
printer
scanner
VHS player
TV
cassette deck 1
cassette deck 2
humidifier
DVD player
router
home a/c unit
home air handler
can opener
food processor
bread maker
shredder
dishwasher

I haven't any idea how much it would cost to replace all these items, but I suspect it would be in excess of $12,320 US (that's cost value - imagine the time and transportation to replace them all). Call it $20,000. Let's do that for 2 billion people and call it $40,000,000,000,000, or $40 Trillion.

No thanks.

neilzero
2010-May-14, 08:27 AM
Hi Mugaliens: At first I was appalled by your list. Then I realized that wife and I have had only three of those items ten years in addition to some stored in the shed with zero usage for many years = planned obsolescence. It appears a ten year transition period would result in few additional items being retired. In a way the 7 transitions in our 70 years, have been expensive, but are you sorry you transitioned from VHS to DVD to perhaps blue ray the coming Christmas? I confess to mixed emotions. DC versions of all those items are possible and practical, when and if, the DC alternative becomes available. I suggested a pilot program, not a total switch. Neil

Strange
2010-May-14, 09:27 AM
I saw an interesting proposal to combine hydrogen distrubution with power distribution (if we move to hydrogen-based cars, etc). The power cables are enclosed in pipes carrying liquid hydrogen: the conductors are superconductiing so losses are reduced; more hydrogen can be delivered in liquid form. The initial infrastructure costs are huge, of course....

HenrikOlsen
2010-May-14, 10:34 AM
I saw an interesting proposal to combine hydrogen distrubution with power distribution (if we move to hydrogen-based cars, etc). The power cables are enclosed in pipes carrying liquid hydrogen: the conductors are superconductiing so losses are reduced; more hydrogen can be delivered in liquid form. The initial infrastructure costs are huge, of course....
I see rather large losses from cooling the hydrogen, plus rather nasty accidents should pipes rupture, which they will, given that it'll be nearly impossible to make them non-brittle at those temperatures and economical to produce at the sane time.

Larry Jacks
2010-May-14, 01:38 PM
We should do a pilot program of homes and businesses powered by DC instead of AC. It is especially advantageous for using electric and hybrid electric car batteries and home battery banks to smooth peaks and dips in the grid voltage. Inverters can provide ac for the rare device that is impractical for DC. Neil

One problem with the idea is that it's much harder and less efficient to change voltages when you're using DC as opposed to AC. Different items need different voltages. Consider home electronics - they all have power supplies to convert the AC input power to DC but the output voltages differ according to application. Now consider high power consuming items like appliances, e.g. stoves, refrigerators, washers and dryers. If your home is wired to supply the DC voltage needed by electronics (typically less than 12 volts and often less than 5 volts), the current loads you'd need to run a clothes dryer or stove would be in the hundreds of amps. To handle high current, you need large and expensive cables. On the other hand, if you use a better DC voltage for appliances (say 200+ volts), you're going to have a hard time with the electronics.

To change voltages with AC, all you need is a simple and quite efficient transformer. It's a lot harder and less efficient with DC which is the primary reason Westinghouse won over Edison all those years ago.

lomiller1
2010-May-14, 06:16 PM
As pointed out above HVDC is very attractive for long distance and point to point power transmission. AC is far superior for local distribution.

The reason people are talking about HVDC for solar and wind is because even though the energy available from these can vary a LOT on local scales on continental scales the amount of energy they can produce is relatively constant. This is fine, but it means you will frequently be generating excess power thousands of kilometers from where that power is needed so you need a highly efficient long distance power distribution backbone to get power from where it’s available that day to where it’s needed.

neilzero
2010-May-14, 08:51 PM
I 'll concede superior, but not far superior, as we may find great solutions as we do the pilot program. Older computers don't use ac; they use plus and minus 5 volts and plus or minus 19 volts and most other electronic circuits can run on these 4. I agree we need at least one more voltage, perhaps 419 volts to fast charge electric vehicles and the home battery banks and 400 volts to float the charged battery across the neighborhood grid to reduce the grid spikes and dips. Most everything else can run on either 38 volts or 400 volts dc. Likely OK for most industrial applications. What do you think? Neil

lomiller1
2010-May-14, 09:33 PM
The processor in a PC is typically drawing 40 -80 Amps at just over 1V. This isn’t something you can practically supply from a power supply so what it does instead is supply +/- 12V and run it though a circuit that is effectively an inverter/transformer/converter in the mainboard.

Power distributions systems face the same problems, they need to use higher Voltages in order to transmit the same power at lower Amperage. Hence the HV part of HVDC. Yes, you could step this down for household use with converters/inverters but transformers do the same thing and are a lot cheaper.

jj_0001
2010-May-14, 09:57 PM
[

One problem with the idea is that it's much harder and less efficient to change voltages when you're using DC as opposed to AC.


Um, whoa there. Down conversion via switching supply technology is almost frighteningly efficient and very inexpensive. Upconversion is a bit more expensive, but no more inefficient.

Your comment was true 20 years ago, but the world has changed. Many power wall-warts are now simply do rectification and then use a switcher. That's how all of my laptop supplies work, and how it appears most of the others (which work on 90-240v 50-60 Hz inclusive) work, as well, without even getting very warm, and I must say that having a 90 watt supply 1/2 inch thick by 2" by 4" that barely gets warm at full output isn't wasting much power, either.

cjameshuff
2010-May-14, 11:08 PM
One problem with the idea is that it's much harder and less efficient to change voltages when you're using DC as opposed to AC. Different items need different voltages. Consider home electronics - they all have power supplies to convert the AC input power to DC but the output voltages differ according to application. Now consider high power consuming items like appliances, e.g. stoves, refrigerators, washers and dryers. If your home is wired to supply the DC voltage needed by electronics (typically less than 12 volts and often less than 5 volts), the current loads you'd need to run a clothes dryer or stove would be in the hundreds of amps. To handle high current, you need large and expensive cables. On the other hand, if you use a better DC voltage for appliances (say 200+ volts), you're going to have a hard time with the electronics.

The first thing your PC's power supply does with the AC fed into it is rectify and filter it to produce moderately high voltage DC...often 170 V or 340 V or so. This is then fed through a switching converter to produce the several very high current, low-voltage, regulated DC supplies needed by a personal computer. Efficiencies are high, typically greater than 90% and even up to 98-99%, which can actually be less than the core and copper losses of a transformer and rectification/filtering circuitry on the low voltage side, and the power supply is far smaller and uses less copper and iron than one based on a single large 60 Hz transformer would be. It's not just inefficient to make a transformer-based supply for today's home computers, it's completely impractical.

Diodes drop a certain voltage when forward biased, and dissipate power proportional to the product of that approximately fixed forward voltage drop and the current flowing through them. Rectifying low voltage AC at high currents greatly increases the power dissipated as heat in the diodes. When you're supplying 3.3 V at tens of amps, and rectifying/filtering 6.5 VAC with a bridge of diodes with a forward drops of 1.4 volts, you would be spending ~40% of your power on heating diodes...which will then require monster heat sinks and fans for cooling. You'll also need huge, very low ESR filter capacitors and more regulation to get something you can use.

When you're rectifying 120 VAC, rectifier losses drop to a couple percent and it's far easier to produce the regulated high-current low voltage. The switching converter can then use smaller, more efficient high-frequency transformers or inductors and filtering capacitors.

Most modern electronic devices, including the vast majority of those on mugaliens' list, use or can trivially be redesigned to use DC. Many will operate better, particularly nonlinear devices that only do their work around the peaks of the cycle such as LED lights. Do the rectification in a central location at higher voltage, and overall rectifier losses will drop further. DC household power distribution really makes sense. Unfortunately, the closest thing to a standard for DC power is the utterly inadequate USB standard...

Murphy
2010-May-15, 01:38 AM
Why those places? And why choose such a large area of comparison just to give such a small percentage?
It's hard to picture the sizes of those places to begin with.
Surely there's not more or less light falling on those places than other mid latitude areas.

Either they actually plan on putting this stuff there, or they just picked an area that doesn't sound like it will agitate the NIMBYs.

There are real technical reasons for wanting to put Solar panels in the Sahara and Middle East. It's just about the best land on Earth for Solar power.

Check out these Insolation (http://en.wikipedia.org/wiki/Insolation) maps:

http://img64.imageshack.us/img64/7247/worldsolarradiationlarg.gif
http://img189.imageshack.us/img189/2302/insolationworldmap.png

As you can see, the amount of Solar power available is not just related to latitude, its also heavily influenced by the amount of cloud cover, so even though the tropical jungle areas on the equator might be expected to get the most light, actually they are very cloudy which looses a lot of potential. Deserts are defiantly the best for Solar. Plus there's the added bonus of not having to pave over some useful or ecologically valuable areas like Farmlands or forests, you can just put the solar plants in areas that are already almost uninhabited by people and other life forms.

There's been many serious proposals to gather huge amounts of solar power in the Sahara, see Desertec (http://en.wikipedia.org/wiki/Desertec).

mugaliens
2010-May-17, 07:25 AM
Hi Mugaliens: At first I was appalled by your list. Then I realized that wife and I have had only three of those items ten years in addition to some stored in the shed with zero usage for many years = planned obsolescence. It appears a ten year transition period would result in few additional items being retired. In a way the 7 transitions in our 70 years, have been expensive, but are you sorry you transitioned from VHS to DVD to perhaps blue ray the coming Christmas? I confess to mixed emotions. DC versions of all those items are possible and practical, when and if, the DC alternative becomes available. I suggested a pilot program, not a total switch. Neil

Well, I could annote a copy with how long I've had them, but it'll suffice to say that 11 ofthem are older than 10 years.

I have a better idea. Since the efficiencies of DC exist over the long haul, and the efficiencies of switching back and forth are so very inexpensive in this day and age, them install the equipment down to the local power substation. Beyond that, use the current lines, transformers, house wiring, and appliances to transmit the last few miles to homes using AC.

NEOWatcher
2010-May-17, 06:05 PM
There are real technical reasons for wanting to put Solar panels in the Sahara and Middle East. It's just about the best land on Earth for Solar power.

Check out these Insolation (http://en.wikipedia.org/wiki/Insolation) maps:
Interesting. I was hoping there was a technical reason based on the wording of the article.

neilzero
2013-Jan-03, 10:06 PM
Hi mugaliens on 12 May 2010: You and I think your sources are biased. A million volt rms 60 hertz ac power line peaks at 1,414,000 volts: That results in severe corrona losses and corona corrosion, while these problems are much reduced at one million volts dc. At any voltage a long ac power line radiates significant energy into space, unless the 4 or more wires are transposed at 100 meter intervals or oftener = the transposing increaces the length of the wires by perhaps 1/10 percent = more copper, more insulators and more loss. The dc power line may be more valnerable to EMP = electromagnetic pulse than the ac line with lots of transpositions, which is one reason I suggested car and house batteries floating across the dc power line.
Recent and soon improvements in dc make the only advantage: AC is presently installed. Neil

Ronald Brak
2013-Jan-04, 01:18 AM
The economic advantage of point of use solar in that it competes with the retail cost of electricity rather than the wholesale cost may limit the construction of utility scale solar farms and thus the need for improved transmission. Currently here in Australia rooftop solar produces electricity at about half the cost of buying electricity from the grid. As point of use solar helps us meet peak demand it reduces our need to upgrade transmission infrastructure. Also we're approaching the point where the difference between what many people pay for grid electricity and what they can sell their solar electricity to the grid for is so large it makes home or business energy storage cost effective, which also helps take a load off transmission. So while HVDC transmission lines will be built, we may not need nearly as much capacity as some people expect.

publiusr
2013-Jan-05, 06:41 PM
Here are some links in terms of possible energy breakthroughs
http://nextbigfuture.com/2013/01/magnetic-power-inverter-ac-voltage.html
http://article.wn.com/view/2011/02/11/Compact_hightemperature_superconducting_cables_dem onstrated_/
I've always had an interest in Superconducting magnetic energy storage: http://www.superpower-inc.com/content/superconducting-magnetic-energy-storage-smes

neilzero
2013-Jan-06, 06:22 AM
Thank you Wayne for that detailed analysis. We can nit pick a few points, but you have shown that SPS power on the grid costs more than one dollar per kilowatt hour, compared to perhaps 20 cents from solar farms. Both have an additional cost of delivering the power to the customer. The latter does not have an economy of scale. Worse it costs perhaps 20 times as much to send 1000 megawatts from New Mexico to California as it does to send 100 megawatts. That is mostly because the transmission lines to send the 100 megawatts already exist. It is even worse to send the power from New Mexico to the USA East Coast.
SPS risk to life property and the environment is generally thought to be negligible for nearly all SPS proposals for the first 1% of the World's energy needs = we can safely re-evaluate when and if we ever reach 1%.
40 minutes of usable solar per day. You are seriously underestimating the cost of a world wide grid to significantly mitigate the low and no output periods, and/or the cost of energy storage to mitigate.
Pro 24 hour operation. It is average 23.9 hour operation in GEO, less any down time. Competitive systems will have down time also.
How much does the satellite weigh without the solar cells? Good question. The structure needs to be strong enough to survive the launch stress. It may never be practical to unfold square kilometers of panel launched from Earth so we are thinking fabrication at asteroids and/or in orbit, both possibly far in our future at reasonable cost. Stress is thousands of times less in free fall, so in theory the weight can be less than the weight of the solar cells which may also be thin film. The laser diodes and their individual optics can likely be about one cubic millimeter, so even 500,000,000 of them are a minor portion of the weight. The copper wire to inter connect several billion components spread over several square kilometers may be about half the weight, and the copper may be the largest environmental impact of the entire SPS fleet. Manufactured in free fall and the vacuum of space, there may be several lighter and cheaper alternatives to copper such as sodium.
The optimum attitude changes very slowly, so it is likely practical to rotate the entire several square kilometers of solar panels to keep them facing the Sun. That is why I suggested a flexible power line between the solar panel array and the laser diode array, as it needs to rotate differently to be kept aimed at the receiving site on Earth. One million volts is optimum for one gigawatt, so there is likely no economy of scale for building SPS rated more than one gigawatt. Thus you are correct: we need lots of them, even for 1% of the world's energy needs.
The microwave SPS is likely somewhat heavier = more massive as the transmitting antenna needs to be a square kilometer or more while the 500 million laser diode array can possibly be as small as 20,000 centimeters = 200 meters on each of the 4 edges.
The solar paint may be 20% efficient facing the sun, but that falls to less than 5%, average, since many surfaces never face the sun and those that do, it is only for a few hours per day, but yes, it is competitive, if it cost $20 dollars per gallon and is not much harder to install than conventional paint. How do we make the electrical connection to the paint? My house looks spotty as we have re-touched many spots = an exact match is impossible. Will we use the solar paint on portions that are shaded most of the time? Is repainting with solar paint practical when it starts looking dingy or peels? I'm finding repainting is easier than washing. Can the solar paint survive pressure washing? Neil

loglo
2013-Jan-06, 09:50 AM
The solar paint may be 20% efficient facing the sun, but that falls to less than 5%, average, since many surfaces never face the sun and those that do, it is only for a few hours per day, but yes, it is competitive, if it cost $20 dollars per gallon and is not much harder to install than conventional paint. How do we make the electrical connection to the paint? My house looks spotty as we have re-touched many spots = an exact match is impossible. Will we use the solar paint on portions that are shaded most of the time? Is repainting with solar paint practical when it starts looking dingy or peels? I'm finding repainting is easier than washing. Can the solar paint survive pressure washing? Neil

I am not sure solar paint is at the stage where it can be applied directly. This recent article (http://www.newcastle.edu.au/achievers/our-staff/something-new-under-the-sun.html) from University of Newcastle is talking about printing onto plastic sheets for now. Commercialisation is due in about 3 years.

tusenfem
2013-Jan-06, 10:34 AM
Hi mugaliens on 12 May 2010: You and I


neilzero, if you would have taken a look you would have found that mugaliens has been banned from BAUT (now CQ) for a long time already. So don't expect an answer from him. If you want to revive all these years old threads (of which you have several at the moment), then please look whether the person you want to discuss it with is actually still active on the board.