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Comment by manacit | Hacker News Reader

Perhaps not just when prices are negative, but it's not an uncommon practice to 'store' power by pumping water uphill when it's cheap and demand is low (generally at night), and then using that potential energy to generate and sell it when electricity is more expensive.

I have absolutely no clue what it would take to make that profitable, but it's a strategy for handling the natural spikes of demand when using power generation methods like solar and wind that are unable to adjust quickly to changing demand.

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>I have absolutely no clue what it would take to make that profitable

You need a large watershed with a wide range of useable head. It is an excellent system when the geography and hydrology allows for it.

Unfortunately, such areas are not common or evenly spread, and are not really possible to economically construct without a great deal of cooperation from the local geology.

You also need one where you're given significant environmental carte blanche. These types of projects are similar to dam projects in the scope and scale of the amount of the environment that they destroy, times two as you need upper/lower ponds.

Your lower pond could be the sea.

So then you're pumping salt water into (presumably) a fresh water lake. I don't think that decreases the environmental damage.

Yep, your upstream lake should also be saltwater.

I honestly do not think there is anywhere in the world that has easy access to the ocean, a large potential hydraulic head, and a pre-existing elevated saline lake to work with. Maybe somewhere in the Atacama? Is there enough power demand in the region to make it worthwhile?

[edit] I did find a very small seawater pilot project that was dismantled last year in Okinawa. https://en.wikipedia.org/wiki/Okinawa_Yanbaru_Seawater_Pumpe...

As the sibling comment shows, you can build an artificial lake large enough to be feasible. The Okinawa plant seems to have been decommissioned for lack of need (at its given cost). It was probably a victim of the current oil/gas extraction boom and artificially deflated oil prices. Still, I wonder about their ability to control costs due to corrosion--salt water is horrible for this reason.

I couldn't find much more about the site in English, but considering how expensive the lining must have been for what was a pretty small storage pool, in addition to needing expensive materials like stainless steel and assorted specialty plastics to deal with corrosion...

I can't know for sure, but regardless of whether they say it was due to weak demand or not, I bet it was the saltwater issue that sunk the project more than anything else.

Salt water corrosion is a big issue, but, if you're making a large upper pond, you're still causing massive environmental damage.

Also where this geology is present that is usually far away from the places where it is economic to deploy wind-turbines, and often from where it is economic to deploy solar panels.

Also, what "greens" often ignore: these giant storages, are dams on flatter areas are often also devastating to the environment.

I hadn't realized that the incentive structures could make it possible for an organization apart from the energy producer to run such a facility. An elegant application of market economics.

A lot of hyrdro plants have exactly that ability. Buy low sell high.

So they could now make money when buying AND selling?

Just like everything else, yes.

I don't think there are too many products that you can make money from buying. The few I can think of are things like bee hives (paid to remove it and paid for the bees), dirt/sand in abundance areas (I'm not sure they sell it), and other natural resources. Most of them you're getting paid for removal and not buying though.

Housing and real property can sometimes effectively work that way, where you are paid for buying because you are taking on responsibilities by purchasing the property(say, for liens, cleanup, etc)

A business that wants to shift a loss making division could be the same.

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