Hacker News Reader

Comment by toomuchtodo | Hacker News Reader

There’s about 100GW of solar generation in ERCOT’s interconnect queue at the moment. If there is uncertainty, utility scale developers aren’t signaling it.

https://news.ycombinator.com/item?id=32071998

> As of 30 September [2021] developers had 100.3GW of solar capacity in the queue, 42.4GW of utility-scale battery storage, 22.5GW of wind, 13.5GW of natural gas and minor amounts of other technologies such as biomass.

For comparison, ERCOT has a maximum capacity of 15GW of coal generation, and 65GW of fossil gas generation (per electricitymap.org, which sources zone capacity data in the US from US EIA-860 reporting).

View on HN

Well if you are a solar developer it makes sense to get in line in the interconnection queue and hope that this stupid tariff stuff gets sorted out before it's time to actually buy all the panels. But I bet we'd have a lot more installed all over the US if it weren't for this.

> But I bet we'd have a lot more installed all over the US if it weren't for this.

Agreed. Solar PV module tariffs are suspended for 24 months FYI, so there is some near term policy clarity for utility scale developers. The ITC tax credit is also phasing down over the next 2 years, so the incentive is there to build build build.

https://www.utilitydive.com/news/biden-to-pause-solar-tariff...

https://www.whitehouse.gov/briefing-room/statements-releases...

Since batteries are always the issue... How inefficient is mechanical storage? For example using electricity to just raise a heavy mass then as that lowers it can produce power. It seems that would be cheap to build at scale with the chance for almost unlimited storage.

I have to assume there would be a more than 50% loss through the process, hope someone on hn can comment. Maybe it's not worth it when you can tap into unlimited sunlight the next day.

Not worth it, easier to scale up battery manufacturing (which the world also needs for all vehicles to transition to electrification).

https://youtu.be/iGGOjD_OtAM

This system is currently only cost-effective with water, and only where you have a natural place to put it (i.e. a crater on top of a mountain vs. building a tank on a tower). Constructing a greenfield mechanical apparatus is too expensive for the energy stored.

People are actively researching and working on kinetic energy storage systems, for example https://www.energyvault.com/ev1

> How inefficient is mechanical storage?

The density is the problem.

If you raise a 25,000kg mass by 100m, that's 24.5MJ, or roughly the energy contained in one kilogram of coal. Or 6.6kWh (standard meter units) of electricity.

(and that's on the input side, not accounting for losses)

.. or, if you want a fun comparison, a 2000kg Tesla with a 100kWh (360MJ) battery pack would have to be raised over 18km into the air to equal the energy stored in its battery.

That’s not how water storage works though for example. You are forgetting that for every unit of mass raised 1 unit, you can add another unit of mass where the previous unit was. Thus you are getting a progression of 1+2+3+4…up to the height units of power stored.

The water tower in my town is several hundred feet tall (many units) and has a big bulb tank at the top. When you pump a gallon of water up into the tank, it is raised hundreds of feet and contributes a fraction of an inch to the total height of the water stored.

It's an actual implementation of energy storage, the water is pumped up there and then gravity distributes it, so there is a buffer if the pumps can't run for some reason.

Pumped hydro is usually considered the best way to do this. Basically, you pump water from the bottom of the dam back up to the top. This is great because you probably already wanted most of the infrastructure for hydroelectric power; the pumps are a relatively inexpensive addition once you have that. There are other techniques, but pumped hydro is generally what you'll see for this reason.

Flywheels are also pretty good short term, but supercapacitors mostly do their job better these days. That said they are competitive, and technological changes could nudge them into more use. Just making your wind turbine really large gives a flywheel effect, e.g., so again if you already have a spinning thing they are often worth it.

> 100GW of solar generation in ERCOT’s interconnect queue at the moment.

This seems mad - is that built and not connected, or just awaiting permitting?

Interconnection listing is one of the first stages for a project; but that doesn't mean that all of these projects will go through.

It does give a good sense of investor sentiment between relative technologies, however.

Reply on news.ycombinator.com