Comment by onemoreact | Hacker News Reader

Comment by onemoreact | Hacker News Reader

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That post was written by someone with a vary superficial understanding of these issues. For example Hydro power already provides a lot of 'grid storage' and is totally missing from his analysis. Also, photovoltaics are far less impacted by clouds than you might assume with partially cloudy days offering similar power levels to sunny days. And even on days where it rains constantly you get some power and often see an increase in wind power output.

Smart grids enable many applications like large scale cooling to shift of demand without building new storage infrastructure on the supply side. Not to mention simply shifting maintenance cycles can shift a lot of 'supply' to different parts of the year without building any infrastructure at all.

Add it all up and Wind + Solar meet total energy demands and have near ideal capacity factors with ~2-4 new hours of total grid energy storage. VS. the 6 days which he assumes.

PS: http://arstechnica.com/science/news/2010/04/it-looks-like-ti...

There's a limit to how far you can expand hydro. There aren't that many more places to build dams. You can expand a little more by putting reservoirs at higher elevations specifically for storage, but that's expensive.

Even at 4 hours of storage, the scale we need is a bit mind-boggling.

Your link is really interesting though. That's the kind of analysis we need. I see too many articles that just talk about rated capacity with no consideration of actual output or reliability.

My second link does similar analysis for Australia, and there it doesn't work out so well. The wind drops low over wide areas for days at a time.

In any case I have nothing against renewables, as long as they don't use up too much land...offshore wind is perfect. But I think we should be building GenIII and better nuclear reactors, too.

Hydro is already used for peaking power, at most we would retrofit things it increase peak power output where it's reasonable to do so.

Building 4 hours of storage is a rather extreme step that's also extremely unlikely. California already has a 40c/kwh cost differential between peak summer demand and the middle of winter, but nobody is building massive grid energy storage to smooth that out. Even over the course of a single day you could make 10c/kwh just from grid storage but nobody is building it. Rather we add peaking power plants because base load power + storage costs more than peaking power plants and that's likely to continue to be the case even in a world dominated by solar + wind power plants.

If you use hydro for peaking, you increase the impact of hydro on the environment.

A hydro plant running at baseload has a river downstream that is like... a river. Water levels vary with something close to the natural rhythm.

A hydro plant used for peaking will have no water flow for hours, and then heavy water flow. That puts extreme stress on organisms living downstream.

You mean just like the natural pattern of storms and snow melt that the areas you build hydro in already have?

Hydro here have carefully regulated flows to reduce the natural variation in the river so that for example an optimal flow is created for the various salmon runs.

Rivers don't have constant flows so it's more natural to have variable output than constant output. And dam's never have zero output, it's more a question of 30-80% and back down.

http://www.deseretnews.com/article/700006602/USGS-Gains-from...

2-4 hours of the worlds entire energy consumption is staggering large amount of energy. You also need the currently non-existent capability to move massive amount of power around the globe.

I just came across some free software for designing energy systems incorporating renewables: http://homerenergy.com/

"The HOMER energy modeling software is a powerful tool for designing and analyzing hybrid power systems, which contain a mix of conventional generators, cogeneration, wind turbines, solar photovoltaics, hydropower, batteries, fuel cells, hydropower, biomass and other inputs."

Edit: looks like it's for small-scale installations.

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