Power grid change may disrupt clocks

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  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Power grid change may disrupt clocks

    Very well then.
    First, I will restate that the man in question is a PhD and has spent his life designing software that controls the grid here in NA and several other countries in the world. This is his response to my inquiry regarding the additional unbalancing of grid power by RE sources. It tends to the anecdotal rather than a barrage of data, as he is speaking to me not lecturing some room full of executives as is his normal practice. Also, the tone is a bit condescending; a bad habit he's developed from years of trying to explain things to politicians. I will also reiterate that many of you won't like what he says.

    I will then post my own synopsis.

    I have no dog in this fight, as the hill-williams say. But I do see this field being dominated by loose concepts, populist slogans, political opportunism, manufacturing lobbies, and wishful thinking.

    I can safely say that, in any electric power system, a large percentage of renewable energy sources is an absolute nightmare for the power system operators. This translates into voltage and frequency fluctuations, and brown or black outs. It also implies more expensive electricity to counteract those dangers. There is some potential for CO2 reduction, but not too great.

    You are correct that the impact is small when solar and wind represent a very small proportion of the power generation into the grid. But this is not where things are going. Solar power is still in its infancy. Wind power implementation is vastly more advanced. Driving through Europe, we came across farm after farm of huge wind turbines. Driving from Phoenix to LA, you pass a farm of about 2,000 modern windmills just outside Palm Springs. Spain already has 20% of wind generation. Germany is not far behind, and Denmark is around 50%. The targets for many US states are in the 20-30% range. Sounds wonderful. Not.

    The problem is that wind power is intermittent. As a power system operator, what do you do when the wind reduces or dies down completely? Or when the wind is too strong and the turbines have to be shut down? You have to have already scheduled fast standby MW generation to take up the lost wind power as quickly as necessary. In principle, this means providing one MW of fast standby generation for every MW of renewable generation -- an enormous and enormously expensive level of duplication. This requirement (in practice somewhat less than one-on-one) is provided by (a) not retiring otherwise obsolete inefficient thermal plant so that it can be kept online (boilers fully fired and working, ready to be loaded up, at great cost), and (b) buying enormous amounts of gas-turbine generators that normally go unused but can ramp up their output very quickly to replace lost wind generation.

    Obviously, it is a seductive notion that wind power is geographically diverse - when it wains in one place it waxes in another - but this is not always true. So, as well as the problem of limited capacity to transmit power from one place to another, the unfortunate utility companies have to cater for the worst case when there is a wide-area lull in the wind during a major heat wave or freezing spell. If they fail to cater for such a worst case, huge blackouts will certainly occur, at the worst possible times.

    Another more technical major factor is power system stability. The rotors of the power system's synchronous generators are massive and rotate very fast. So they have huge stored energy and rotational inertia. Because they are all connected via the electric network, they have a very strong mutual synchronizing "pull". That is, all of them naturally try to rotate at exactly the same speed (corresponding to 60 cycles per second). But this synchronicity can be disrupted by any big power system perturbation, such as the outage of a major transmission line or a generator, and this might lead to instability and complete system shutdown. Renewal generation such as wind has almost no rotational inertia. Solar has little or none. Therefore renewable generation is both a weak stability link on its own and it makes little contribution to maintaining system-wide stability. This may require the provision of additional transmission apparatus at further capital cost, and/or a more expensive way of operating the power system.

    So, I suspect that the "lying scoundrels" might actually be feeding you the gospel truth, right on the nose. Everywhere in North America and Europe, power engineers who have no incentive to dissimulate on behalf of their respective companies are developing ulcers and heart conditions over the increasing inoperability of their power grids, as a result of renewal energy installations. The people raking in the shekels are the manufacturers of wind turbines, solar systems, and their delivery apparatuses. The people making political capital are the ignorant and/or cynical green-flag-waving politicians who have voted subsidies and incentives for renewal energy.

    In all this, the transmission grid and electricity market not-for-profit operators are like deers in the headlights. They have no ability to stop the politically-driven and subsidized tidal wave of renewable energy. But they somehow have to find and pay for all the reserve and reliability that renewable generation is sucking out of the power system. This is going to cost the consumer. You have to remember that in North America in general, most suppliers of electric energy are separated from the operators of the energy delivery system (i.e. the transmission grid). But the latter have to anticipate the need for and request additional generation for reserve, which becomes increasingly large compared with the good old days when generation was not intermittent.

    Green always sounds sexy but is not necessarily good. It all depends on the details. Germany is now changing its main emphasis to solar power. So-called "solar thermal" generation is quite attractive. It focuses the sun's rays to heat up large vats of molten salt or similar, to produce steam to drive generator turbines. The mass of salt represents the storage of energy - the holy grail of electricity production - which can be released over perhaps 12 hours. The capital costs are more than wind turbines, but this is counterbalanced by a much reduced need to provide vast amounts of fast-standby generating reserves. It is said that the net cost is less, and that frequency and voltage deviations and blackouts are much less likely.

    In summary, as I see it, if the consumer is being hoodwinked in all this, it is by the venal and uninformed politicians and by the purveyors of renewal energy equipment (is there a connection?). But in any case, the huge uncertainties represented by renewable energy will inevitably lead to much higher electric power costs and reduced reliability of supply. Any reduction in pollution is likely to be small. Of course, any time there is wild confusion and uncertainty about overall costs and expected amounts of renewable generation, the scenario is ripe for concealing profit and/or for pricing that hedges against going into the red.

    My vote is for nuclear generation in geologically stable locations (not, obviously, Vancouver). One of the leaders of the green movement in Europe, who was previously dead against nuclear generation, has done an about-turn as a result of the Japanese disaster. He says: if Fukushima represents a worst-case scenario, it is vastly less harmful to humanity than the mining of coal or shale-based oil, and their use for electricity production.


    Further remarks he made in another message:

    One coming way of combating very short-term frequency fluctuations, exacerbated because renewable sources have little rotational inertia, is to install flywheels. In this respect, these perform the same function as synchronous generators. In the long run they can be cheaper than running old uneconomical thermal generating units in the same mode, to stabilize frequency. In New York, they have installed 160 small (about a ton each) magnetically levitated flywheels solely for such frequency regulation. Note of course that this does not address the need for expensive hot-standby or quick start-up reserve generation to cater for rapid more-sustained loss of wind or sun. One of the keys is to develop much better highly localized wind and sun short-term forecasting. In some places, such as Arizona, sun forecasting is easier. In other places where patchy cloud is normal, like BC or Northern Europe or the US east coast, forecasting the strength of the sun even minutes ahead can be hit and miss - all the more reason for the attraction of thermal solar plants (the ones with the molten salt), albeit expensive.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Power grid change may disrupt clocks

    My synopsis:

    Conventional power generating sources have a degree of predictability; it may take time to bring them on-line or off-line, but the operators know what amount of time this is. They are not really weather-dependent in any way. Neither solar nor wind have these advantages. As a result, if we rely on solar & wind more the amount of unpredictability in power generation increases. This is already starting to show up.

    Usage is only predictable to a certain amount. Throw in some unexpected variables such as bad weather (turning on more heat or A/C) and it gets worse. In combination with a larger amount of unpredictable generation and you can easily see how the trick of balancing varying supply with varying demand becomes difficult. We do this all the time with off-grid systems: having to have back-up generators for when the sun doesn't shine and building in a certain amount of excess capacity as well as "optional" loads that can be switched off if power is not available. But with the off-grid scenario, the same person controlling production controls consumption. That is not true of the national utility grid by any means. The grid is also millions of times larger.

    We also forget that the grid is not a single entity. The distribution network is one part, the power generation is many different companies (often working at cross-purposes), and the consumption is by millions of individuals, businesses, and industry. Now try to co-ordinate activity among those factions, getting all those people to agree. Then throw in politicians whose only knowledge of power management is testing which way the wind blows on any issue deemed important so they can go with (often short-term) popular opinion and retain their own personal political power.

    The grid is already unstable for factors not relating to RE source inclusion. It has been getting worse over the decades. The first big indicator something was wrong was the East-coast blackout of 1965. The problems that caused that have largely been ignored, mainly because utilities are in business to make money. I have heard my friend describe the grid as "a tangled nightmare of over-loaded extension cords that everyone keeps plugging more things in to".

    Renewable Energy sources aren't going to help, because the management problems will still be there. They don't have good enough ways of dealing with the existing system and they have no plan for including RE; it's just been forced on them with no foresight to the long-term (as usual).

    I shall stop ranting now. I could tell you about some of the other little marvels of power management I've been privy too, but you'd all only become even more upset.

    No flaming, now; you did ask for this.
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: Power grid change may disrupt clocks
    This requirement (in practice somewhat less than one-on-one) is provided by (a) not retiring otherwise obsolete inefficient thermal plant so that it can be kept online (boilers fully fired and working, ready to be loaded up, at great cost), and (b) buying enormous amounts of gas-turbine generators that normally go unused but can ramp up their output very quickly to replace lost wind generation.
    There's two solutions here which should be used anyway regardless of whether or not we continue adding more wind/PV (I should add that not all renewable sources are as intermittent as wind/PV so it's unfair to paint all renewables with the same brush). If you look in the news they are already building solar thermal plants capable of 24/7 operation - and then there's geothermal and small-scale hydro (which can be used for grid storage as well) and some others I'm forgetting about, too.

    1. Modern CCGT plants - Obsolete inefficient thermal plants should be retired in favor of modern CCGT plants. These plants are about 60% efficient today and have vastly better ramp rates - around 50 MW / minute.
    2. Grid storage - Instead of having tons of "spinning reserves" replace them with a variety of grid storage - utility scale batteries, flywheels (as he touched on). This will contribute to the current grid's efficiency and stability. There was news about a proposal in New York for a peaker plant - one of the proposals was not for a gas turbine - but for something like 200 MW of grid storage (don't recall if this was using batteries or flywheels - think the former so not the same as the smaller 20MW flywheel storage that just came online).
  • BB.BB. Super Moderators, Administrators Posts: 32,013 admin
    Re: Power grid change may disrupt clocks

    We discussed Beacon Flywheels in this thread a few years ago...

    Flywheel based electrical storage

    I have not looked at their website today, but it took a fair amount of power to keep those flywheels spinning back then (somewhere around 2% to 8% losses per hour--guessing by reading PR Literature at the time).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: Power grid change may disrupt clocks

    Looks like Beacon claims a 85% efficiency for a charge/discharge cycle:

    http://www.beaconpower.com/files/Flywheel_FR-Fact-Sheet.pdf

    Do have to wonder how much energy it loses per hour... Flywheels may be better suited for frequency regulation than shifting load from peak to off-peak where it may need to store energy for 12+ hours.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Power grid change may disrupt clocks

    One thing that he glossed over is the fact that for better or for worse, fossil fuels are going to run out some day, and it takes a lot of fossil fuel energy to build a nuclear power plant. What this says to me is that unless the storage problem is solved, the days of a centralized power grid are numbered, even if at this point it is still a fairly large number. The synchronicity of our clocks will be the among the least of our problems.

    I have spent the last three years retooling myself toward a new career in solar power, and his remarks are not going to make me change course, no matter how much he vilifies the industry. YMMV.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Power grid change may disrupt clocks

    ggunn;

    I agree that fossil fuels' days are numbered. The pollution factor isn't even mentioned either. However, I don't think he's vilifying the industry so much as saying we do not currently have viable technology to incorporate RE into the grid for exactly the same reason as for the problems the grid suffers from now: no efficient way to store surplus production against later demand. If we insist on switching to wind and solar prematurely we will only be exacerbating the problem, as they don't have either the rotational mass storage (for the most part) nor the ability to be brought into production at will (being dependent on weather).

    Let's remember that wind turbines in many parts of the world this year had to be taken off-line so that hydro production could be ramped up full to relieve the backed-up water behind the dams. There was at that time a glut of electric energy available, and no way to store it for later or distributed it far afield (so that more polluting plants could be shut down).

    Solve the energy storage problem = solve the energy problem.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Power grid change may disrupt clocks

    for what it's worth i agree with him that re cannot be a primary power source with some hydro sources as an exception. he complains of the vast numbers of generators needed just in case the re sources go down, but he fails to realize that without re, those generators would not be just in an occasional standby position, but in a fully operational status. the problem isn't the re sources, but the utilities not being able to manage the power let alone maintain a failing grid. the problem exists whether re is here or not, but right now it is a problem to make most re sources as a primary power as the technology if there is not an easy or cheap solution to make it a primary source of power. i always was of the opinion that re does have its limits, but the bellyaching by utilities to me is too soon with re sources still low in % and they are transferring the problem to re sources as an out for problems that would exist even if re sources weren't there in some capacity. no, we won't see a wiping out of those generators, but i am of the opinion that re is reducing the numbers of those generators in full operation and does help.

    as far as the utilities are concerned we aren't seeing much innovation or solutions to the power problems that exist and to just blanket blame re for their shortcomings and woes is crap imho.
  • solar_davesolar_dave Solar Expert Posts: 2,382 ✭✭✭✭
    Re: Power grid change may disrupt clocks

    I agree predictability is pretty low for most forms of RE, except for places like AZ, New Mexico, SoCal. Perhaps the proper way to to provide the flywheel technology to solar PV to smooth the systems out and to provide carry forward generation.

    I could envision a 1 ton flywheel driven by a DC motor and connected to a DC generator to provide the rotational inertia even at the residential grid tie level. Certainly that technology could be used in the large PV solar array plants or wind farms spinning up around the country. In any case that would provide for a more gradual transition in the source of RE to allow operators time to replace the generation without leaving things in full standby.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Power grid change may disrupt clocks

    ted,
    i think that flywheel would certainly need to be way much larger than 1 ton, but why a dc generator if re sources would run the dc motor? it would still be spinning in standby for some time with losses.

    on 2nd thought i wouldn't trust any utility with properly maintaining the flywheel as i could see it ultimately breaking loose and rolling out of the building and down the road taking out everything in it's path for miles and they would cry, "we needed more $ to upgrade and maintain it" just like they cry now about a bunch of high tension wires they call the grid that they aren't doing so well with.:roll:
  • solar_davesolar_dave Solar Expert Posts: 2,382 ✭✭✭✭
    Re: Power grid change may disrupt clocks
    niel wrote: »
    ted,
    i think that flywheel would certainly need to be way much larger than 1 ton, but why a dc generator if re sources would run the dc motor? it would still be spinning in standby for some time with losses.

    on 2nd thought i wouldn't trust any utility with properly maintaining the flywheel as i could see it ultimately breaking loose and rolling out of the building and down the road taking out everything in it's path for miles and they would cry, "we needed more $ to upgrade and maintain it" just like they cry now about a bunch of high tension wires they call the grid that they aren't doing so well with.:roll:

    LMAO that puts some pictures in my mind! :roll:

    I was thinking a vertical axis Flywheel, much safer in the lose of a bearing, perhaps air bearings to support it. Yes it would need to be sized according to the installation but I don't think the purpose should be a long term storage device, just something to make the RE more predictable. You know smooth off the lumps in the curves.

    Yeah I think back in the 50's and 60's they had so much more capacity in the grid compared to the load it was not an issue, plus burning fossil fuels was the norm and standby power was dirt cheap. Less the case today. Now we pay for the neglect brought on by wall street and accountants looking for the next quarters profit picture.
  • nsaspooknsaspook Solar Expert Posts: 396 ✭✭✭
    Re: Power grid change may disrupt clocks

    To restructure the output of RE power generation (wind) to better match the profile of conventional rotational devices might require a large percentage of full power output to be stored as an inertia buffer.
    http://www.google.com/url?sa=t&source=web&cd=9&ved=0CEMQFjAI&url=http%3A%2F%2Fwww.labplan.ufsc.br%2Fcongressos%2Fpowertech07%2Fpapers%2F258.pdf&ei=engYTo2cB4TViALa95jSBQ&usg=AFQjCNEoSA-NDncuggKuiN2X5IrBTncniQ&sig2=1UXTu0K6ugi9YAdviAa-RA

    Inertial emulation from deloading helps but at the expense of peak power production from non-MPPT operation, ~30% in China per this paper.
    http://www.csee-conference.org/uploadfiles/20101110145716356.pdf

    I guess a positive from the current recession and cool weather is that power usage here in the NW (baseload levels) has dropped to the point that are starting to see these problems now instead of later.
  • nsaspooknsaspook Solar Expert Posts: 396 ✭✭✭
    Re: Power grid change may disrupt clocks

    http://www.extremetech.com/extreme/92018-is-the-smart-power-grid-too-smart
    Is the smart power grid too smart?
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