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Transitioning to 100 percent renewables

Germany hits 50 percent solar, Ireland 50 percent wind

Reports about new record shares of renewable power are understandably celebratory, but they also confuse the public – and even experts. What’s worse, these peaks are an indication of solar’s limits without storage. I’m not sure that something to celebrate. At least we can go much further with wind power.

If you haven’t already heard the news, “Germany produces half of energy with solar” – at least, that’s what the website The Local would have us believe (incidentally, don’t click on the link unless you want several ads to blast you with audio, but here it is).

Of course, by “energy”, the journalist means electricity only. And the figures reported by Fraunhofer ISE are preliminary: a record 24.24 GW for one hour on Friday, June 6, followed by 23.1 GW briefly on Monday, June 9.

The latter occurred on a public holiday (Pentecost Monday), so that amount of solar was reportedly enough to meet 50 percent of peak power demand briefly. However, other data do not confirm that outcome. The data used by Agora Energiewende have solar peaking at below 23 GW on June 9 with domestic power consumption at nearly 54 GW. So solar made up at most 43 percent that day depending on what figures you use. (Fraunhofer will not publish its full estimate for this month until next month.)

Agora Energiewende

Some prominent people (who not only should know better, but probably do) are nonetheless firing off tweets that overstate the case; perhaps it is a natural outcome of being limited to 140 characters.

Nonetheless, some comparisons are unfair, such as when this prominent Dutchman puts Germany share of solar energy at 50 percent, compared to “only 0.2 percent” in the US.

Here, Meneer Verbeek unfairly compares a peak solar power production record in Germany to the annual average in the US – not cool.

But even people like Al Gore get the story completely wrong when they have the space to get things right. In a long article published this week at Rolling Stone, Gore claims that "Germany… now generates 37 percent of its daily electricity from wind and solar." In reality, Germany gets only a third of that amount – closer to 13 percent. Gore Is simply confusing peaks and averages.

With all of these knowledgeable people getting the soundbite wrong, it’s no wonder we end up with claims like the one below in reaction to an article at Think Progress based, alas, on Bernard Chabot’s analysis we published here.

Think Progress

I tried to explain the issue carefully over at EnergyTransition.de, but unfortunately the article from here focusing on the raw data – without so much embedded information – went viral.

Interestingly, Ireland recently saw its share of wind power peak at 50 percent of power demand, an issue that went largely unreported (why is everyone so focused on Germany?). “On average,” as this report explains, “wind energy supplied 23 percent of the electricity market in the December 2013 to May 2014 period.”

If we return to solar in Germany, we see that PV made up just over five percent of domestic demand last year. Assuming it increases to six percent in 2014, we now have solar peaking at half of demand but only making up a small sliver of the total share. The limits of solar in Germany without storage are coming fast.

 - On the day when solar allegedly peaked at above 50 percent of German power demand, the residual load for conventional plants remain high enough for prices on the exchange to stay in the positive.
On the day when solar allegedly peaked at above 50 percent of German power demand, the residual load for conventional plants remain high enough for prices on the exchange to stay in the positive.
Renewables International

If we double the amount of solar in Germany, we end up with peaks at 100 percent of demand, which will completely wipe out not only baseload plants (which must run), but also whatever wind power and biomass we happen to have at the time. In other words, Germany will need to start storing or simply losing solar power when PV makes up a mere 10 percent of demand. Compare that to wind in Ireland, and you see how much further you can go.

In Germany, the situation with wind is similar. Last December, we had around one third wind power for roughly a 24-hour timeframe. Wind power makes up nearly 9 percent of German power supply. Triple that, and you can get a quarter of your power from wind without storage or curtailment.

In other words, we can go at least twice as far with wind as we can with solar in countries like Germany and Ireland, which have higher power demand in the winter than in the summer (in many parts of the US, the opposite is true, so the potential of solar is much greater).

And incidentally, in the Agora chart above, did you notice that at 9 PM on June 7 we had around 9.4 GW of renewable power, though demand was still slightly above 58 GW. German conventional power plants were running at 44.5 GW at the time, and the country was a net importer for a few hours that evening. Those who celebrate these record peaks would be well advised to look for the nearby lows, which are often just a couple of days away. (Craig Morris)

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16 Comments on "Germany hits 50 percent solar, Ireland 50 percent wind "

  1. heinbloed - 04.08.2015, 10:56 Uhr (Report comment)

    Ireland hits 58% wind power at peak load (18:00) yesterday 3/8/2015 and 54 % on Sunday the day before. Monday 3/8/2015 was a public holiday.
    System demand:


    Wind generation:
    The Eirgrid data is difficult to research, I couldn't find hydro and biomass power data which still has to added to get the total RE production.

  2. Serious Joe - 17.11.2014, 22:59 Uhr (Report comment)


  3. Todd Millions - 28.06.2014, 22:14 Uhr (Report comment)

    Photomofo-Rerefrigeration.Industrially-chillers for ac and refrigeration use water cooling via sailine loops in N.America.Your point on heat buildup is valid.But as a Canadian I'm instictively used too the Idea of your car boot being a quite satifactory frezzer for much of the year.This is a point too ponder as -freezers and fridges ,can be kept in unheated porches conveinent too the kichten door-thus reducing the heat delta T tempture difference they must work against.This allows panel output in winter too be shifted to lighting -when these loads peak.I recall that a mass produced steel house in the 1950's,had the radiator for the fridge,blow warm air thru a cabinet that dried the racked dishware and towels.I forget the name.Currently the power figures for panel alone frezzers(seeSundanzer),are in the 600 watt hr per day range. My own design work on these lines is a tad more twisted,but I've only design too show as phycopaths I'm related too keep destroying my materials to demonstrate before I actually have much too show for it. Vexing given the help they receive in these endevours from neibours who are necrophiliacs. But-An oversize Kerr through the wall solar oven(it goggles)of 2 M2 glazing. Run a copper pipe thru the top of it,connected to a insulated indoor hot water tank,with a drain dowm system.Under the oven. A through the wall frige door for a ammoina absorbsion refrigerator(which has too have outside venting under N.Americian regs).Summer -boiling hot water drops thru the heating tube that runs the fridge on its way too the storage tank.Insulation of this fridge must be boosted of course for night and cloudy days,as well as ice block 'ballast'. Winter-the heated water by passes the fridge and goes direct to storage,while cold reduces(or eliminates) the need too power the fridge.If you start with the oven,the water heat loop and then refrigerator can be added after-reducing cap with no payback issues. An added bonus is that such self finacing is something loathed and feared by banksters the world over.Cheers and Thanx.

  4. photomofo - 28.06.2014, 18:09 Uhr (Report comment)

    Possibly... We've figured out how to run water pipes to the refrigerators for automatic ice making and such without worrying about insulation or micro-circulation. The savings may be more like 300 +/- kWh a year because you've got the higher efficiency of the fridge stacked on top of the waste heat recovery in the water heater and the possible waste heat avoidance with the AC system.
    Let`s say you`re right that the savings are generally too low for the hassle. Fine... But what about tinkerers and what about off-grid applications where high efficiency is more important? What about something like the solar decathlon? Would it work there? Only time I've ever heard of water cooled compressors is with commercial refrigeration and I've never heard of those systems recovering the waste heat.
    Could be more of a Legionnaire's disease type of a problem.

  5. Ulenspiegel - 28.06.2014, 13:24 Uhr (Report comment)

    "I can't figure what's so tough about running a tube from the refrigerator to a small undersink hot-water tank. "
    You have to insulate the pipes, you have to prevent microcirculation, IMHO not worth the potential gains of ~150 kWh per year, in autum/winter I have no problems with hot air in my kitchen. :-)

  6. photomofo - 27.06.2014, 23:31 Uhr (Report comment)

    Todd... Refrigerators are good target. Sure they only use 1 kWh a day but there are lots and lots of them and they're autonomous. Refrigerators started out as ice-boxes. The idea of adding a 2 liter ice-battery back into the standard design is hardly earth-shattering. One inefficiency with refrigerators that's been puzzling me is why do we use air to cool refrigerators instead of water? Water cooling would be more efficient. The hot water waste output could easily be sent to a small kitchen sized under-sink hot water heater. This arrangement would capture around 1 to 2 kWh of productive waste heat per day for cleaning dishes and such. In cooling climates like Italy, California, Saudi Arabia this arrangement would also reduce the load on your AC system because you're not dumping waste heating into your living space. I can't figure what's so tough about running a tube from the refrigerator to a small undersink hot-water tank.

  7. Todd Millions - 27.06.2014, 03:10 Uhr (Report comment)

    The follow up to this that would be very useful,would be a comparision of the consumption and efficency of german industry and households,with the same in ireland and scotland.With attention to the gains possible. Electricity to hot water tanks is easy but-So is storing cold as ice in fridges and freezers designed for intermitencies of days.If you lose the grid,this feature really starts paying for itself,exspecially seasonally with PV.It also some what fubars attempts to eliminate the feed in tariffs in that you have a large essential load that you don't need the grid for.As well the power not dumped too the water heater tanks is available to charge EV bikes,dalniks ect.I really get worried when AL Gore gets excited,and 140 character restrictions don't help.The inventor of the interweb,has poor tastes in his enthusiasims and company in my opine-but don't take my word for it,ask a Yugoslav.

  8. James Wimberley - 26.06.2014, 20:34 Uhr (Report comment)

    Greg: Good catch. From slide 6, the peak irradiations caught by pure E and W oriented systems are at about 0830 and 1530. They have only half the total output of a S facing system (slide 7) for standard cells. Off-axis output may improve at all orientations with better anti-reflective coatings, an dreduce the absolute gap, but this won't affect the peak times.
    So it's technically possible to have a PV park that generates flat output between those hours (7 hours a day). This would be very inefficient, so it won't happen. However, there is still quite a lot of scope for flattening the solar fried egg by enouraging a wider set of orientations. Whether this is worth doing depends on many other costs, especially those of storage and tracking.

  9. heinbloed - 26.06.2014, 15:18 Uhr (Report comment)

    Scotland hits the 50% mark of combined RE-power as well:

  10. Greg - 26.06.2014, 14:34 Uhr (Report comment)

    Re: East/West PV - looks like the answer is not much.

  11. James Wimberley - 26.06.2014, 12:47 Uhr (Report comment)

    Greg: I googled your exact question and got some interesting links, but no proper study. It's easy to calculate overall output with PvWatts, but the domestic version doesn't give the hourly distribution. The NREL also offers a much more detailed professional solar calculator called a href="https://sam.nrel.gov/"SAM, but I haven't the courage to dig into it.
    It does look as if residential installers are unfamiliar with the concept of multipl eorientations - each orientation should have it own string inverter, or use microinverters.
    As panel prices and the supply of South-facing roofs is used up, we will see a lot more E and W installations. An ideal FIT or PPA would price morning and evening production higher than noontime.

  12. Greg - 26.06.2014, 05:27 Uhr (Report comment)

    How much can east/west facing PV help to spread the midday peak? Has anyone seen any research on this?

  13. photomofo - 25.06.2014, 23:02 Uhr (Report comment)

    "Wind power makes up nearly 9 percent of German power supply. Triple that, and you can get a quarter of your power from wind without storage or curtailment."
    Really? So if you had 105 GW of wind you think there'd never be any curtailments on a windy holiday? This is unlikely.
    Germany should be able to expand solar two or three fold without too much trouble. You could dump your noon-time peak solar energy into your domestic water heaters. I'd estimate the potential at around 2 kWh per house per day at noon. You could think of that as 1 kW supplied for 2 hours or more of a bell curve shaped block of power supplied during the solar peak event. The French, Brits and Germans all did this with storage water heaters sponging up off-peak nuclear power. Works great... Lasts a long time. Pretty obvious solution.
    Take whatever projection you want for PV in some future scenario - 100 GW for example. There's a graphical representation in the projection with a stretched crescent shaped chunk of PV that's in excess of load. Traditionally we think the excess will either need to be stored, spilled or exported. This view isn't imaginative enough. Ask yourself... Can the amount of flexible load in the system be made big enough to fill up the stretched crescent shape. If the answer is yes then you can balance supply and demand without resorting to storage, spilling or exporting power. The more flexible load you add the more PV you can integrate without the maxing out the traditional balancing tools. In the past we've been able to control the system with stored fuel. In the future will have to control the system with more stored services, spilling and storage.
    Question... have German pumped hydro plants been running during these peak solar events lately?

  14. Thomas - 25.06.2014, 21:34 Uhr (Report comment)

    @James: I think you are very right. Crutailment is not a tragedy, but an opportunity.
    In the end of the day, wind & solar aren't power plants anyways. They are energy sources.... using them to meet at-the-time electricity demand is the (very) low hanging fruit.
    We have to move toward using them for heat & transport, and yes, eventually also store them in batteries or as gas. The first two are potential cash cows for the energy transformation. The later could very well end up cheaper / easier than we can imagine today.
    The official goals for 2050 require us to handle "oversupply" about 60% of the time. Gotta start some time -)

  15. heinbloed - 25.06.2014, 16:50 Uhr (Report comment)

    Absolute true, James Wimberley. On oversupply of 'free' electricity is nothing to worry about. P2G and other storage methods are already being installed. Recently I found a PV-company offering free electricity from the grid if one purchases a battery pack from them. They would take surplus power from the grid and send it to their batterie owning clients who get this electricity for free, up to 800kWh/year from September 2014 onwards. The company on the other hand would get paid by the grid authority to stabilze the grid taking the surplus.
    With 800kWh/a for free and a PV-equipment owned the average house owner could become an electricity bill-free household, in theory.
    Other companies might follow, the grid stabilisation is a service payed for by the grid owners.

  16. James Wimberley - 25.06.2014, 15:57 Uhr (Report comment)

    I agree we should not be fixated on the solar peaks - and that includes you, Craig. Where's the disaster in overproducing solar for an hour at noon in summer, and curtailing output? Sun is a free resource. Try modelling a high penetration of 50c/watt solar with up to 25% curtailment: I bet it will still pay.
    A 100% renewable world, which is where we want to be and Germany is actually aiming for, is going to be one with massive overcapacity by today's standards much of the time. Solar at 150% of peak demand would cover most June days, wind at 150% of peak demand might cover most November evenings - and you will need both, plus another 100% of peak demand in backup for windless November evenings. The good news is that with wholesale prices around zero, the electricity for P2G and pumped storage will be virtually free. (The high capital charges of all this gear are a fixed cost.) How Gabriel and Oettinger can reconcile this prospect with their market obsession beats me. Plenty is disconcerting to economists.

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