For example - utility scale storage (pumped hydro); distributed storage (home batteries and Vehicle-to-grid battery Ev cars); demand-side management; power-to-gas (hydrogen); and geographic grid integration.
See more at
http://www.nrel.gov/analysis/re_futures/
https://www.raponline.org/featured-work/teach-the-duck-to-fl...
http://cleantechnica.com/2016/03/02/base-load-power-is-a-myt...
http://cleantechnica.com/2014/08/08/rmi-blows-lid-baseload-p...
Pumped hydro is probably the best bet, but is very geography dependent. Adding transmission is a non-trivial investment.
https://www.greentechmedia.com/articles/read/First-Grid-Scal...
We have a pumped hydro solution where I live. It's huge and only supplements a small power plant.
"One of the striking things about the ARES project is its size: 50 MW of power capacity and 12.5 MWh of energy. That would be large for a battery storage project, but for ARES, it is on the low side. “Fifty megawatts doesn’t get us to economies of scale,” CEO James Kelly said. “We are more efficient as we get larger.”
Kelly said ARES projects can be sized anywhere from 50 MW to 1 GW. “If we had a 500 MW project, we could double the capacity and it would only increase capital costs by 20%,” he said."
Could they perhaps achieve high enough mass in a small volume by using eg. lead?
Could it be that a train is more efficient at converting potential energy than a water turbine?
Could it be that they have a longer drop?
You gotta show your assumptions if you're arguing through back of the envelope calculation.
Not all locations have a lake (or 2) conveniently located near a large elevation drop.
The article says "They move up and down an 8-degree slope with an elevation change of about 3,000 feet", that's a lot of energy.
A reservoir 10m deep and 45m square at the same elevation has the same potential energy. If you can find a convenient 1000m plateau I think it would probably be cheaper to build a reservoir on top than to build the tracks and trains.
Now I wonder how fast these railcars move.
I wonder how hard it is to scale though.
See this for a comprehensive annual survey by Lazard on storage technologies and costs
http://blog.rmi.org/blog_2016_01_21_how_much_does_storage_re...
You could build surface level reservoirs as two tank hydroelectric dams, and then use the water as an energy reserve as well as freshwater reserve.
Non-trivial in terms of size and politics, but an extremely solid one that will reduce the cost of electricity.
That's a very specific claim, and I don't think your cited graph even supports it.
Presumably, you say "this time of year" because you know that the yearly peak in California is driven by air-con usage in the summer afternoons, which correlates very well with solar.
But even right now, in early May, the graph is mostly flat through the afternoon and evening, with only the slight peak at 8 or 9 at night making your statement true in a very narrow sense.
Notably however, the graph only includes grid side solar production, so panels on homes or business roofs are not included in the graph. If you added those to the total demand curve would shift upwards during solar production hours.
Yes, solar can help meet peak load during the summer, but not the rest of the year and it causes stress on the system by requiring a lot of power to spin up to meet demand and solar decreases.
You don't know when peak demand in California was yesterday, because you're looking at a graph of the utility company's electricity production, not electricity demand. You'd need to add all the self-consumption by "behind-the-meter" solar installations on homes and businesses to find out the real demand peak. From the perspective of CAISO, solar self-generation is indistiguishable from reduced demand.
We know from historical figures that the absolute highest yearly peak in California, the one that you need to build your grid to withstand at great expense even if it only requires that load for a short period of time per year correlates well with solar, and so solar saves lots of money by shaving that peak.
The "duck curve" is also not a demand curve, it's demand, minus self-generated-solar, minus grid-generated-solar. And even then, it only appears in the winter months, when demand in California is on the low end of the yearly cycle something like a third of peak demand in the summer months. (Note the graphs showing the duck curve in your second link are from January and March).
I don't think that explains everything about the demand curve, but using the current day demand curve to say 'solar doesn't work' isn't looking deeply enough.
I like the Arthur Clarke quote: When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong. - Arthur C. Clarke
Note that Solar isn't "hurting". Because such demand right now is being covered by Natural Gas Peaker Plants anyway.
Natural Gas Peaker plants are expensive, so if we can replace some of their usage with other energy sources, that'd be great. Eventually, we might be able to transition off of them with sufficiently advanced energy storage technologies.
And once baseload power starts getting "replaced", we enter the realm of coal plants and nuclear plants reconditioning themselves so that they can be scaled up and down a bit better.
I know both coal and nuclear power require many minutes to change their energy production, but if a smaller-scale energy storage (~30 minutes) can be created to hold out during the scaling up / down period, the problem could be solved.
As opposed to say, load-shifting pure solar energy (which requires a storage capacity measured in hours, not minutes). High power / low time can be solved with standard Lead Acid batteries or maybe Flywheels (cheaper technology than Lithium Ion, which would be better for hours of storage)
https://www.raponline.org/featured-work/teach-the-duck-to-fl...
Industries and homes find innovative ways to adapt to market pricing. All the appliances there have options to use power at night (when it is cheaper there). For solar, the times may be different but the same idea remains. Commercial power is priced at a premium when the grid is overloaded (typically winter months).
[1] http://residential.edf.com/energy-at-home/offers/electricity...
"Technicians say that the Noor 2 and 3 plants, due to open in 2017 will store energy for up to eight hours – opening the prospect of 24/7 solar energy in the Sahara, and the surrounding region." http://www.theguardian.com/environment/2015/oct/26/morocco-p...
Think of the battery as a really big capacitor operating on a larger time-scale. It's perfectly reasonable to smooth out power this way, and as battery technology improves, you will certainly see more reliable power from solar for things like server farms.
https://news.ycombinator.com/item?id=11595195
I agree storage (if required) and environmental impact should both be considered when comparing different energy options.
Energy storage is improving rapidly. Lithium-Ion batteries are but one technology that I don't personally expect will become the norm at grid-scale.
> The larger Powerwall was positioned as a longer-term back up power supply, which GTM noted was looking like a hard sell, with other market alternatives that were priced far below the $3500 price tag.
> The remaining 6.4 kwh device has less capacity, and is designed more to shift the load of available power, such as from a solar panel, to times when the production of such energy is lower.
Also the Powerwall is for home use. For utilities they offer Powerpacks, and they are already on sale:
There's nothing stopping anyone from getting more than one battery to make up for the capacity that was offered by the larger model.
https://www.caiso.com/Documents/CaliforniaISOPeakLoadHistory...
It's true that the daily peak is in the evening and that won't be helped by solar. But grid generation capacity is built to handle the annual peak, not the daily peak, so the annual peak is what matters. And because the annual peak tends to be hot afternoons, solar actually will replace other generation in the long run.
I used to analyze this stuff professionally when I worked at a California utility.
Is it just too hard to move electricity so far away?
In the short term, transmission lines are congested during peak hours so we often can't pipe enough power to high demand markets.
“Let’s Build a Global Power Grid - IEEE Spectrum”
http://spectrum.ieee.org/energy/the-smarter-grid/lets-build-...
Maintaining fiber optic cables can be hard across the ocean. How about a power line that has a diameter of 50 feet? I can't even imagine the engineering of that.
Info on losses here: https://en.wikipedia.org/wiki/Electric_power_transmission#Lo...
No idea on the math for what % of power we would lose across the ocean.
Seems local batteries would win out..
The circumference of the earth at the equator is 24,901 miles. Halfway around the world, we'd deliver 29% of original power.
The holy grail in transmission is high temperature super conductors. We're not there yet.
The difference between solar and coal is that the output of coal is more reliable.
It is correct that coal does not ramp up or down quickly, but that is not a characteristic of dispatchablilty.
It's exists between something like nuclear (which has to just be on for months at a time) and natural gas peaker plants (which turn off and one during the day to meet demand.
You could, for example, run coal plants during the winter (when there is little sun) and not during the summer. Or you could run coal on cloudy days. Or just turn it off on weekends.
(I understand your actual point, and agree with it)
Solar reduces the base load required and makes the maintenance and capital costs of coal stations higher.
http://electrek.co/2016/05/03/worlds-largest-coal-supplier-b...
the only question is, can politicians be convinced to do something good for the country which may not keep them in office?
It's a different game altogether - batteries etc instead of train cars full of coal. But it will happen.
http://arstechnica.com/science/2016/01/making-a-single-us-el...
http://rameznaam.com/2016/01/31/how-far-can-renewables-go-pr...
Coal provides baseless power--coal plants are designed to run at a relatively steady level for more than 90% of the time. Reliable power is critical for things like server farms which draw power all the time. Solar cannot serve the same purpose without battery or other backup.
At this time of year in places like California, solar doesn't help meet peak demand either. http://content.caiso.com/green/renewrpt/20160503_DailyRenewa... Solar has a role, but comparing it to coal is misleading.