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Prediction: Coal has fallen. Nuclear is next then Oil.

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Grid-independent... using the grid as a backup.

One of the reasons Tesla is merging with Solar City is to take advantage of Tesla batteries. This will allow Solar City to fight some of the shenanigans utilities like APS are attempting to protect their market share.


The Solar City business model still operates mostly on the lease model. They pay for the system and you lower your electric bill on day 1... that's for the 99%.... not the 1%. Adding storage to the mix makes solar PV economically viable in areas that the utility is pushing back against solar.

Batteries are projected to be <$100/kWh and Solar modules <$0.30/w by 2020.... these estimates have a long history of being overly conservative... Where do you think nuclear will be? At what cost point will you agree that nuclear simply can't compete?

By "grid-independent... using the grid as backup", you mean import only from the grid, correct, with no export (or at least, no plan for financial gain from export once the battery backup is fully charged). Correct?

I ask because somewhere along the line, it started sounding like off-grid, and I think everybody is in complete agreement that there's a big leap from net zero and off-grid.

This in-between state I see here - "grid-independent using the grid as backup" - sounds like a very sensible way point for many people to aim for.

My situation will be similar to @David_Cary's above, and for most I suspect. I can get through the summer easily, and a lot of the spring and fall. Especially as solar installation falls in price, I've got a whole 'nother side of the house that doesn't yet have panels! So I can overbuild there and add 10's of kwh of panels, and I could be exporting many days of the year should I want. The problem with off-grid of course is that in the winter, the 70 kwh summer day can go below 1 kwh, and routinely under 5 kwh. My current lifestyle and home doesn't function on 5 kwh in a day :)

BUT - grid independent with imports as needed. Yeah, that's easy. That gets me through the 2 worst months in the winter, and the bill is close to 0 the rest of the year.

And if it really does look to the electric company like I'm a seasonal user of small amounts of electricity, with a correspondingly small electric bill, then this option creates consumer choice options in utility districts where the electric company is being particularly .. contrary.
 
I don't contribute much to this thread, but I find the discussion very informative. Both WRT the nuclear issue, and the bigger picture question of how the seasonal sun variation is the primary roadblock to 100% renewable energy. That probably even deserves it's own thread.

wk057 has shown what can be done to get almost completely "off grid", but even he faced the dreaded winter conundrum of having to reconnect and fill up his batteries. I can't be the only person wondering what the eventual path to 100% would be. Many posters here are providing some good info.

Anybody have any idea if there is a "magic bullet" that might appear in say 20 years? Insanely low cost dense batteries? Small portable fission reactors? And then linking that into either the current grid or the grid that exists 20 years from now, yikes!

RT
 
I don't contribute much to this thread, but I find the discussion very informative. Both WRT the nuclear issue, and the bigger picture question of how the seasonal sun variation is the primary roadblock to 100% renewable energy. That probably even deserves it's own thread.

wk057 has shown what can be done to get almost completely "off grid", but even he faced the dreaded winter conundrum of having to reconnect and fill up his batteries. I can't be the only person wondering what the eventual path to 100% would be. Many posters here are providing some good info.

Anybody have any idea if there is a "magic bullet" that might appear in say 20 years? Insanely low cost dense batteries? Small portable fission reactors? And then linking that into either the current grid or the grid that exists 20 years from now, yikes!

RT

The seasonal variation is an issue... for solar... but wind generally produces more in the winter so that helps to compliment solar. IMO we need ~2 weeks or ~150TWh of very low discharge storage to reach 100% renewables. There are a few items that can fit this bill;

- Hydrogen fuel cell
- Synthetic Hydrocarbons
- Metal - Air battery
- Metal Powder as fuel

Since there will be significant curtailment periods of solar and wind by the time we get to ~80% renewables the round trip efficiency of this tech is far less relevant. Getting 20% of a watt that would have otherwise been curtailed is still a win. There's lots of other possibilities... hard to imagine we won't find one that works.
 
I'm not even sure how much seasonal variation is a problem for PV if a robust, long distance grid is developed.
And as you say, we already have hydro, bio-mass, batteries, demand management, over-building and wind to fill in any gaps today, and a host of possible candidates tomorrow.

This is a political rather than technical question, and nuclear is not invited to the table because it is too expensive (and sucks, but that is somewhat besides the point.)
 
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Anybody have any idea if there is a "magic bullet" that might appear in say 20 years?

There are a number of current solutions to the seasonal variation problem that might take center stage when we get there. The issue really boils down to cost per kWh with very long cycle times (6 months). The contenders are cheap thermal storage (sand etc), methane and hydrogen (as storage systems, not energy sources).

I did the calculation of sand thermal storage for my climate (7500 HDD), and the result was that for a Passivhaus level of energy efficient house, one could heat a given square footage with an 8 foot deep basement filled with sand. That makes a good solution at an individual house level.

Thank you kindly.
 
There are a number of current solutions to the seasonal variation problem that might take center stage when we get there. The issue really boils down to cost per kWh with very long cycle times (6 months). The contenders are cheap thermal storage (sand etc), methane and hydrogen (as storage systems, not energy sources).

I did the calculation of sand thermal storage for my climate (7500 HDD), and the result was that for a Passivhaus level of energy efficient house, one could heat a given square footage with an 8 foot deep basement filled with sand. That makes a good solution at an individual house level.

Thank you kindly.

As much as I hate FCEV's, hydrogen does make for a decent zero-emission seasonal storage system (in place of a gas/diesel back-up generator). If it were possible to produce methane from water and CO2, then a methane back-up generator would be better than hydrogen, since you don't have to worry about 700bar pressure tanks and tank embrittlement.
 
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If I'm understanding the process of creating methane or neaby chemical cousins using excess electricity, the chemicals in the reaction would all come from the air. Take in CO2 along with air and water (maybe the water for hydrogen is in liquid form as input, so taken from a river/stream/pipe), add electricity and a catalyst, and out comes methane (or cousin), with gaseous oxygen as a waste byproduct.

Just at first blush, this sounds like exactly the sort of process we need running and using up excess electricity we will hopefully be generating in abundance soon. Take CO2 out of the atmosphere, while also storing electricity in a form that enables time shifting on the order of seasons instead of hours or days.

Good thing we have that big hydrocarbon storage and movement infrastructure all built out - I wonder what it would take to make it compatible with methane? It's sure an interesting sounding idea.


I wonder if the process is simple enough and safe enough to operate at residential scale? And I wonder how much methane would need to be stored up to burn over the winter for heat / electricity? I would prefer using the excess electricity to get the carbon into a form in which it can be buried or otherwise re-sequestered, but time shifting the energy use is still helpful.

Edit: Here's some information on the Sabatier reaction being talked about here: Sabatier reaction - Wikipedia, the free encyclopedia
 
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I wonder if the process is simple enough and safe enough to operate at residential scale? And I wonder how much methane would need to be stored up to burn over the winter for heat / electricity?

adiggs,
I don't think the idea would be to scale any long term storage process down to the residential level. I would envisage these plants (for lack of a better word) to be similar to a current power plant, in that they generate electricity on site and supply it to the grid. They might have to be larger than the footprint that a current power plant requires because they would be storing something for perhaps 6 months worst case before converting it to electricity, versus simply burning coal, natural gas, or nuclear.

Think 1) vanadium flow battery, 2) liquid hydrogen storage, 3) battery storage. These three examples would all require larger footprints. Assuming the goal is 100% renewable energy system (no burning gas for heat) then the number of storage facilities needed to get over the "winter slump" would vary based on location. The Northeast would require more seasonal storage than the Southwest for example. Someone more in touch with energy consumption by region could probably figure out how many storage/generation plants would be required in any given location. Any oversupply of power at any given time would simply be used to "fill up the storage", whatever the storage scheme is. Something like this would allow the current baseload plants that can't be cycled quickly (nuclear) to still run during the day, you just convert the power at some less efficient rate and pour it into storage. You could think of the collection of the storage/generation facilities in a region as a very large distributed battery. The system would then only need to be sized to capture enough energy during the summer to offset the considerably less sunlight/renewable during the winter. No doubt this is still a very large amount of power.

The thing is, the whole system doesn't need to be built at once. As you start having the problem of too much power being generated during the day such that baseload starts needing to be curtailed, you can start building just enough storage capacity to allow for keeping the baseload running. Once you get a few cloudy days, you can draw down the storage as required to offset the solar loss.

The cost of any storage system would almost certainly get cheaper over time, especially as the technology matures and they start getting produced in scale. Ideally, you would want to start this up as a pilot in an isolated location that gets lots of sunshine and doesn't have a brutal winter that would require a whole lot of energy storage. Think one of the Hawaiian islands. I believe they get something like 80% of their power from oil burning plants. Just start installing as much solar as you can, and build different kinds of storage/generation plants to absorb the mid day oversupply. As the combination of daily renewable out and stored power generation increases, you can start taking the oil plants offline one by one. The goal is 100% renewable. By doing this over a period of years, you allow the price of the storage to naturally decrease because of efficiency and scale. The better performing storage solutions can then be zeroed in on for further deployment. Once the "Hawaii Experiment" is under way for awhile, actual costs should become evident and the plan for rolling this kind of thing out elsewhere will be much better known.

I'll caveat this entire thought experiment by saying that there is a chance that the amount of seasonal energy that has to be shifted from summer to winter is such that it would not be possible to store that amount of power. The thing is though, if you want to get to 100% renewable without having access to unlimited pumped hydro storage capacity, you almost have to store lots of power somehow.

Ideally you could also get rid of the size of the midday solar over supply by charging EV's during peak sunlight hours. And obviously keep driving down total energy required by making everything that uses electricity as efficient as possible. And as someone has previously pointed out, once you start running a significant percentage of cars on electricity, your electricity consumption goes up by a factor of 2x to 3x over just powering homes.

RT
 
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Reading some of those links, I also made that connection of natural gas / methane. So my comment about what it would take to make the current hydrocarbon storage and transport infrastructure was a bit tongue in cheek. We just need a method for manufacturing methane at sufficient scale, and we can stop pumping natural gas out of the ground - instead make new natural gas (methane) from excess electricity, carbon in the air, and water (which could itself come from a desalination plant - yet more energy sink for that excess of production).

And a LOT of solar panels / windmills :)
 
.... Think one of the Hawaiian islands. I believe they get something like 80% of their power from oil burning plants. Just start installing as much solar as you can, and build different kinds of storage/generation plants to absorb the mid day oversupply. As the combination of daily renewable out and stored power generation increases, you can start taking the oil plants offline one by one. The goal is 100% renewable. By doing this over a period of years, you allow the price of the storage to naturally decrease because of efficiency and scale. The better performing storage solutions can then be zeroed in on for further deployment. Once the "Hawaii Experiment" is under way for awhile, actual costs should become evident and the plan for rolling this kind of thing out elsewhere will be much better known.
..........
RT

This experiment is developing quickly on the Hawaiian island of Kauai. They already have so much rooftop and utility solar that it generates 100% of demand for brief periods. Tesla and SolarCity are currently building a large PV array for the utility that will not export solar to the grid. Instead, all of the solar energy will be stored in Powerpacks and the utility will dispatch it as needed after sunset, instead of using their diesel generators. The cost to the utility is about $0.15/kWh, less than running the diesel generators.

Kauai has a goal to reach 100% renewable energy. After proving the concept with this solar/battery array, they will build more until they no longer need to import fuel.

GSP
 
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This experiment is developing quickly on the Hawaiian island of Kauai. They already have so much rooftop and utility solar that it generates 100% of demand for brief periods. Tesla and SolarCity are currently building a large PV array for the utility that will not export solar to the grid. Instead, all of the solar energy will be stored in Powerpacks and the utility will dispatch it as needed after sunset, instead of using their diesel generators. The cost to the utility is about $0.15/kWh, less than running the diesel generators.

Kauai has a goal to reach 100% renewable energy. After proving the concept with this solar/battery array, they will build more until they no longer need to import fuel.

GSP

Thanks for that info, the Kauai PUC approved the SCTY/TSLA project back in March 2016, further info can be seen here:

http://kiuc.coopwebbuilder2.com/sites/kiuc/files/PDF/pr/pr2016-0322-renewableprojects.pdf
 
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Nuclear power advocates are trying a new line of attack on solar and wind energy — it’s too darn cheap!

In the real world, however, the unexpectedly rapid drop in the price of cleantech, especially renewable power and batteries, is a doubly miraculous game-changer that is already cutting greenhouse gas emissions globally and dramatically increasing the chances we can avoid catastrophic climate change.

As I detailed on Monday, the New York Times in particular keeps running slanted articles talking up nuclear and talking down renewables — articles that totally miss the forest for the trees. That culminated in a truly absurd piece last week, “How Renewable Energy Is Blowing Climate Change Efforts Off Course,” which is the exact opposite of reality, as Goldman Sachs has detailed in its recent reports on “The Low Carbon Economy.”

This post will focus primarily on the big picture, the forest. I will deal in later posts with a few of the more interesting trees, such as whether, the U.S. should consider give existing nukes some sort of short-term carbon credit so they are not shut down prematurely and replaced by natural gas.

<snip>
Full article at:
Nuclear Power Advocates Claim Cheap Renewable Energy Is A Bad Thing
 
I have a hard time seeing hydrogen as a reasonable season shifting storage medium for electricity, for the various reasons mentioned by many. Maybe liquid hydrogen is easier to store than hydrogen under high pressure, and gets the necessary volume.

Especially if we can make synthetic methane using carbon from the air, it looks to me like that's a carbon neutral cycle going from carbon in the air, to liquid methane (natural gas), and then burning the natural gas / methane to get the energy back and release the carbon back into the air.

With enough excess electricity and methane production, I wonder if it becomes reasonable to pump some of the excess methane back into the ground and then seal the wells :) It'd be nice to start re-sequestering some of the carbon we've been releasing.


My earlier comment / question about residential scale... I'm totally on board and see the utility of this sequence for season shifting of electricity as a utility scale construct. Big plants creating methane, storing it, and then later burning it to generate electricity. Or make it at one location, and use existing infrastructure to move it somewhere for storage, and then move it again to various plants that burn it to make electricity.

I'm just also wondering if this is a cycle that can be replicated at residential scale, by which I really mean small farm scale. It's reasonably straightforward to find a few acres, up to a few dozen acres of land, at least in the western US to live on. Going off-grid in this situation - the ability to make your own natural gas / methane during the summer and store it in one or more storage tanks, and then burn it during the winter for heat and/or electricity, sounds like an awfully user friendly approach to being carbon neutral and off-grid.
 
I'm just also wondering if this is a cycle that can be replicated at residential scale, by which I really mean small farm scale.

At farm scale, one probably has sufficient resources to avoid the electric->methane step altogether. Collect methane from manure, and use that for seasonal storage (and ongoing usage).

Thank you kindly.