Renewable Energy Storage -- What's Real?

[Merrill]

Ever heard of Sonoma Clean Power? it is an alternative to PG&E. That monopoly model is being eroded by Community Choice Aggregation, ie entities like SCP.

Yes and we are on that, but the problem is that every schedule and program and cost is thru PG&E. so what ever the CPUC desides is what Sonoma Clean Power has to go with.

 

[Ampster]

Yes and we are on that, but the problem is that every schedule and program and cost is thru PG&E. so what ever the CPUC desides is what Sonoma Clean Power has to go with.

The generation charge is set by SCP and you have two levels of renewables to choose from. SCP tries to keep the rates competitive with PG&E rates that have less renewable percentage.The transmission and distribution portion is definitely set by PG & E. I understand that SCP has some pretty good incentives for installing solar, buying EVS and EVSEs. My sister loves in Medocino and is getting SCP soon. I am helping her figured it out.

 

[Merrill]

The generation charge is set by SCP and you have two levels of renewables to choose from. SCP tries to keep the rates competitive with PG&E rates that have less renewable percentage.The transmission and distribution portion is definitely set by PG & E. I understand that SCP has some pretty good incentives for installing solar, buying EVS and EVSEs. My sister loves in Medocino and is getting SCP soon. I am helping her figured it out.

SCP rates are a little less than PG&E but when you add in the distribution and PCIA they are very close to being the same. I have no faith that PG&E will do anything except figure out a way to make more money.

 

[omgwtfbyobbq]

Of all the solutions you mentioned above to solve the renewable energy intermittency problem (which is real and huge), Tesla Powerpacks for utilities and industrial/commercial clients, combined with Powerwalls for residential use, are the absolute best (most reliable and economic) real solution. Much of the rest that Bill Nye (an actor; not a real scientist) mentions are unicorns, beautiful and desired, but very hard to buy for my granddaughter who wants one to feed and pet.

And when I say Powerwalls are "economic," that is really only true when the "spread" of between your local utility's peak electricity rate (e.g., $0.30/kWh) and off-peak rate (e.g., $0.10/kWh) is about 20 cents, assuming you have Time-Of-Use (TOU) rates. I posted yesterday that most people nod off when I get too detailed with math, so I'm going to give the following break-even analysis only for those numbers geeks who understand and care (everyone else, just remember you need about a $0.20/kWh spread between your time-of-use rates before the Powerwall 2 (PW2) is cost justified for you, if saving money is your ONLY criteria). Let's assume the following:
1. Fully installed cost of PW2 is $8,000 (i.e., $5,500 PW2, $700 Gateway, $1,000 installation, $200 permit, $600 sales tax).
2. 11 kWh of energy are stored every day, on average, for the 10-year warranty life, then the PW2 dies. While you may benefit from a longer life, you also are going to have rainy, snowy, winter days where you can't charge much, so let's call that a wash. Also, Tesla's warranty is for 70% of the 13.2 kWh by year ten, so I'm using a simple linear average of 11 kWh [13.2 + (70% x 13.2)/2].
3. $8,000 full cost, divided by 10-yr useful life, means your cost (assuming you have cash and no better opportunity cost to invest your eight grand cause you're waiting for a stock market crash and your bank pays a lousy 0.1% interest) per year is $800. So you need to divide by 365 days to compute a $2.19 "daily cost" of your PW2. Now divide $2.19 by the average of 11 kWh that you'll charge each day (preferably with your solar, otherwise off-peak TOU cheap electricity) and discharge during peak time (offsetting the limited and expensive resource known as peak electricity). $2.19 / 11 = 19.9 cents.
4. For simplicity, I've ignored that you're going to have efficiency losses when you move all those electrons around (e.g., DC solar to AC PW2, etc.). Depending on your situation, this may average round-trip efficiency loss of 10% or so. So that would bump your 20 cent break even up to $0.22/kWh. So now open your next utility bill and see if you have a 20-22 cent spread on your time of use rates?

If someone has PV panels, are you assuming they're storing all the energy they use?

 

[Ampster]

If someone has PV panels, are you assuming they're storing all the energy they use?

Not necessarily. What the other poster was intimating when you have big differentials is that with the right kind of Net Energy Metering you can sell the solar energy generated at high rates and borrow it back at low rates. In that situation it might make more sense to charge the batteries at low rates and use them to run household loads during peak hours so that more of the solar generation gets sold to the utility. That is the way it could work in California but every state is different so your mileage may vary. Then you add the Investment Tax Credit and that adds another dimension where your above assumption may make sense.

 

[EV-lutioin]

So, back to Powerwall-2, I just received a quote from Solar City/Tesla for 2 Powerwalls installed for $13K. When I asked the representative if these Powerwalls were going to pay for themselves in energy cost savings he had no answer. He said they are basically just for backup storage in case of a power outage, which we rarely have here. He said there may be an energy savings based on storing power and using it later, but he was unwilling or unable to crunch the numbers for me. So, at this point I have no idea how the $13K expense will benefit me. My questions are:
1. How do I determine my ROI for installing Powerwalls?
2. How is Solar City/Tesla going to sell these things if they can't provide customers with a viable ROI argument for purchasing them?

 

[Ampster]

How is Solar City/Tesla going to sell these things if they can't provide customers with a viable ROI argument for purchasing them?

Some people will buy them just to have a Tesla on the Wall, others for back up and some to arbitrage rate differentials. I don't think Tesla has to sell them right now because the demand is there. That is particularly true for grid level storage in California and Islands and continents like Australia.

 

[Merrill]

So, back to Powerwall-2, I just received a quote from Solar City/Tesla for 2 Powerwalls installed for $13K. When I asked the representative if these Powerwalls were going to pay for themselves in energy cost savings he had no answer. He said they are basically just for backup storage in case of a power outage, which we rarely have here. He said there may be an energy savings based on storing power and using it later, but he was unwilling or unable to crunch the numbers for me. So, at this point I have no idea how the $13K expense will benefit me. My questions are:
1. How do I determine my ROI for installing Powerwalls?
2. How is Solar City/Tesla going to sell these things if they can't provide customers with a viable ROI argument for purchasing them?

What will be your total kWh and can you apply for the SGIP and what is the rebate per kWh?

 

[Skotty]

So, back to Powerwall-2, I just received a quote from Solar City/Tesla for 2 Powerwalls installed for $13K. When I asked the representative if these Powerwalls were going to pay for themselves in energy cost savings he had no answer. He said they are basically just for backup storage in case of a power outage, which we rarely have here. He said there may be an energy savings based on storing power and using it later, but he was unwilling or unable to crunch the numbers for me. So, at this point I have no idea how the $13K expense will benefit me. My questions are:
1. How do I determine my ROI for installing Powerwalls?
2. How is Solar City/Tesla going to sell these things if they can't provide customers with a viable ROI argument for purchasing them?

Assuming they are set up to where they can load balance, they provide the ability to use more of your own generated energy instead of having to more of less gift it to the grid at poor buyback rates. If your area has net metering, they provide insurance against the end of net metering, something utilities will be pushing for more and more as renewable energy is expanded. They also serve as a valid defense against any person or company that would attack you verbally or otherwise for supposedly adding volatility to the grid without paying for it.

 

[omgwtfbyobbq]

Not necessarily. What the other poster was intimating when you have big differentials is that with the right kind of Net Energy Metering you can sell the solar energy generated at high rates and borrow it back at low rates. In that situation it might make more sense to charge the batteries at low rates and use them to run household loads during peak hours so that more of the solar generation gets sold to the utility. That is the way it could work in California but every state is different so your mileage may vary. Then you add the Investment Tax Credit and that adds another dimension where your above assumption may make sense.

I gotcha. California utilities have been really adverse to battery backup + PV because they don't want you exporting inexpensive off-peak electricity as psuedo-PV output, which makes sense to me because transmission costs make up a large part (majority?) of total electricity costs. If you're just storing energy from off-peak, which has to be transmitted, and sending it back to the grid on-peak as "PV", that'll just increase congestion. Just PV on the other hand is OK because it's sized to your current load, or at least should be close to your expected loads in the future (eg if you don't have an EV, but plan to buy one, you can sign an affidavit to that effect and overbuild your PV based on your anticipated future load), so you should just be covering your own consumption (no T&D) and maybe helping offset of the consumption of your neighbors (a little increase and D, but still a corresponding decrease in T for the utility).

At the same time, if someone were to go off-grid with a powerwall + PV, assuming that's viable for them, their electricity costs would depend on the cost of PV (coPV), cost of powerwall storage (coPW), and percentage of PV generation that can be used without being stored versus the percentage that would need to be stored for later use. For instance, I took a whole year worth of hourly consumption data from my utility (SCE), and compared that to a year's worth of projected production data from PVWatts, and was surprised that as is, roughly half of my power consumption would be directly provided by PV. For me, without changing any habits/etc, my electricity costs with a powerwall would be about .5(coPV+coPW) + .5(coPV). If I were to proactively try to shift loads, I might be able to get close to ~2/3rds powered directly by PV and ~1/3-1/4 requiring storage.

 

[Ampster]

I gotcha. California utilities have been really adverse to battery backup + PV because they don't want you exporting inexpensive off-peak electricity as psuedo-PV output

Yeah, but if your PowerWall is not grid tied because your solar is on another inverter, you can install the PowerWall behind the meter and the only permission that is needed is a building permit. That is the process that worked for me but maybe not optimum for everyone. i was also not agressive about taking the ITC on the batteries and second inverter.

 

[EV-lutioin]

What will be your total kWh and can you apply for the SGIP and what is the rebate per kWh?

I have a 5.5K system. I've applied for SGIP, but no word yet on whether I qualify. Last year we had some surplus production months in the summer and some deficit production months in the winter. I'm not quite sure how to calculate how daily production/use load would justify the purchase of Powerwalls.

 

[Merrill]

I have a 5.5K system. I've applied for SGIP, but no word yet on whether I qualify. Last year we had some surplus production months in the summer and some deficit production months in the winter. I'm not quite sure how to calculate how daily production/use load would justify the purchase of Powerwalls.

Thanks for the info, for me a powerwall will only make sense if the rebate takes care of at least half of the total cost. I'm not sure I can even do a powerwall do to the 200 amp service and the cost of adding another 100 amp panel.

 

[AntronX]

...If you're just storing energy from off-peak, which has to be transmitted, and sending it back to the grid on-peak as "PV", that'll just increase congestion.

No it won't. You will be powering your neighbors on your low voltage distribution circuit. To the utility your exported power will appear as lower overall distribution load. Releasing stored off-peak energy during peak hours will actually help reduce congestion on distribution and transmission lines, and would help prevent utility-scale solar curtailment. Electricity flow does not work like data packets on the internet.

 

[EV-lutioin]

No it won't. You will be powering your neighbors on your low voltage distribution circuit. To the utility your exported power will appear as lower overall distribution load. Releasing stored off-peak energy during peak hours will actually help reduce congestion on distribution and transmission lines, and would help prevent utility-scale solar curtailment. Electricity flow does not work like data packets on the internet.

I love your explanation, and I am not quite sure I fully understand it. Can you give a more detailed explanation? For example: What is a "low voltage distribution circuit".... are there separate circuits within the power distribution grid? I tend to imagine the grid as a large river with lots of small tributaries, each of which can flow either way (export or import), but maybe my analogy is too simplistic?

 

[roblab]

So, back to Powerwall-2, He said they are basically just for backup storage in case of a power outage, which we rarely have here.
1. How do I determine... ?

Since I can only see your address as California, may I say that where I live in CA, we have power outages about 3-4 times a year. The last one was over 40 hours. My backup batteries (8 kWh) kept us limping for one day. That's Napa Valley area.

 

[Ulmo]

but whole blog it's very pro carbon, but non the less CSP numbers are real and tragic

I still want to try lots of different "concentrated solar power" ideas, such as beaming concentrated sunlight into a cement kiln during the day and using similar beams of light emitting electronics at all other non-sunny times of day, using vast amounts of electric generation, but that sounds super inefficient, but I still don't know a better way to supply clean energy for cement kilns. I'd love to see the numbers to see if the amount of pollution saved from not using coal for cement kilns would be enough to offset the amount of pollution used to install the energy storage and energy delivery at dark times of day, as well as the concentrated solar during sunny times of day.

But, CSP for electricity generation in general sounded like a good idea and ended up having lots of problems. Thus, even if research were to start on CSP and/or electrical heating for cement kilns, I have pretty low hopes. I'd still like to know.

CSP is certainly a lot less tragic than Chernobyl or Fukushima....

I find it instructive both happened at a time that those societies were already or becoming increasingly closed, less free speech, cultures that didn't value truth, and things like that. In what used to be the First World (USA, Europe), nuclear power has had successes. We actually use it in a clean way. But, it is true that nuclear power has a high cost of culture, regulation, engineering and maintenance that doesn't exist with solar photo-voltaic panels, so we concede that in a world in which we are trying to decimate the culture of the First World (for better or for worse, whether we are in favor of it or not), a better bet is solar PV power, which doesn't require precise ethics, regulation and maintenance. And don't get started about "nuclear waste": there's basically no such thing -- properly managed nuclear fuel can be recycled. However, that shares much of the difficulties of overall nuclear power, and doesn't escape what I said about nuclear power in general.

However, I'm tired of the lie that nuclear power is intrinsically bad. With proper culture, engineering, design, regulation, care, and maintenance, nuclear power only has three problems as far as I'm concerned: (1) it turns material into heat, thus causing net raise in planetary temperature; (2) it has significant costs; (3) it is not resilient in the face of any downfall of the predicate requirements I listed. #3 tends to be the example that those who want to remove proper culture and care from the society tout as the main problem with nuclear power, so they are self-consistent: because they want to destroy the culture that can support nuclear power, they say that nuclear power is thus unsafe in their vision of the future world. In the vision of the future world that wants to maintain the culture and care that can safely support nuclear power, we say that nuclear power in and of itself is and was fairly good (although better alternatives now newly exist). It amounts to a culture clash. One could even say the conclusions are based upon the goals of the conflicting visions, and that within each vision, their opinion of nuclear power is correct.

I think there's also more to do with some countries attempting to hurt other countries by removing their use of installed nuclear power since it will make the other countries weaker, so they set up protests in the target countries. But that is synergistic with the culture issue.

All of this stuff can be avoided by adopting solar PV + storage, though, so we're going that direction. At least in that we can all agree.

I love your explanation, and I am not quite sure I fully understand it. Can you give a more detailed explanation? For example: What is a "low voltage distribution circuit".... are there separate circuits within the power distribution grid? I tend to imagine the grid as a large river with lots of small tributaries, each of which can flow either way (export or import), but maybe my analogy is too simplistic?

Although many use these terms incorrectly, because it seems to be all relative to what you are used to, they are defined by IEEE for equipment designations as"

LV - 600V or less
MV 601V-69,000V ( Changed a few years ago)
HV - 69,001V-230,000V
EHV 230,001V-800,000V
UHV >800,000

I feel if everyone used these properly a lot of confusion could be avoided. I get a lot of calls for service work and repairs on "High voltage" breakers, when asked if we work on HV breakers my answer is always, some of them, but only up to 115kV, the answer is usually, "I was talking about 4160V" or something like that.

To partially answer your question, Low Voltage is the A/C that travels through your home for electric wall sockets and other hard wired appliances. Interestingly, computational and other kinds of electronics like audiovisual tend to consider that "high voltage", so anybody coming from the audio or computer world may be mistaken thinking that low voltage means something else in power distribution.

Here's some explanations of why they use various voltages in energy transmission; Google around and you can find much more info:

The Physics of Everyday Stuff - Transmission Lines
SolarPro Magazine
http://www.epu.edu.vn/UpLoadFiles/DS05B_V1.pdf

 

[EV-lutioin]

I still want to try lots of different "concentrated solar power" ideas, such as beaming concentrated sunlight into a cement kiln during the day and using similar beams of light emitting electronics at all other non-sunny times of day, using vast amounts of electric generation, but that sounds super inefficient, but I still don't know a better way to supply clean energy for cement kilns. I'd love to see the numbers to see if the amount of pollution saved from not using coal for cement kilns would be enough to offset the amount of pollution used to install the energy storage and energy delivery at dark times of day, as well as the concentrated solar during sunny times of day.

But, CSP for electricity generation in general sounded like a good idea and ended up having lots of problems. Thus, even if research were to start on CSP and/or electrical heating for cement kilns, I have pretty low hopes. I'd still like to know.

I always thought the main issue with cement its release of CO2 as a result of the chemical reaction when making concrete. I hadn't considered the amount of energy that goes into making cement in the first place.

 

[EV-lutioin]

I find it instructive both happened at a time that those societies were already or becoming increasingly closed, less free speech, cultures that didn't value truth, and things like that. In what used to be the First World (USA, Europe), nuclear power has had successes. We actually use it in a clean way. But, it is true that nuclear power has a high cost of culture, regulation, engineering and maintenance that doesn't exist with solar photo-voltaic panels, so we concede that in a world in which we are trying to decimate the culture of the First World (for better or for worse, whether we are in favor of it or not), a better bet is solar PV power, which doesn't require precise ethics, regulation and maintenance. And don't get started about "nuclear waste": there's basically no such thing -- properly managed nuclear fuel can be recycled. However, that shares much of the difficulties of overall nuclear power, and doesn't escape what I said about nuclear power in general.

However, I'm tired of the lie that nuclear power is intrinsically bad. With proper culture, engineering, design, regulation, care, and maintenance, nuclear power only has three problems as far as I'm concerned: (1) it turns material into heat, thus causing net raise in planetary temperature; (2) it has significant costs; (3) it is not resilient in the face of any downfall of the predicate requirements I listed. #3 tends to be the example that those who want to remove proper culture and care from the society tout as the main problem with nuclear power, so they are self-consistent: because they want to destroy the culture that can support nuclear power, they say that nuclear power is thus unsafe in their vision of the future world. In the vision of the future world that wants to maintain the culture and care that can safely support nuclear power, we say that nuclear power in and of itself is and was fairly good (although better alternatives now newly exist). It amounts to a culture clash. One could even say the conclusions are based upon the goals of the conflicting visions, and that within each vision, their opinion of nuclear power is correct.

I think there's also more to do with some countries attempting to hurt other countries by removing their use of installed nuclear power since it will make the other countries weaker, so they set up protests in the target countries. But that is synergistic with the culture issue.

It seems that the safety of nuclear power is dependent on the multiple redundancies required to ensure its safety, which is also what adds to its cost. Therein lies the problem, less safe nuclear power is cheap, but bringing nuclear power production up to the level of safety rightfully demanded by society starts to make it expensive.

 

[Ulmo]

I always thought the main issue with cement its release of CO2 as a result of the chemical reaction when making concrete. I hadn't considered the amount of energy that goes into making cement in the first place.

I didn't know that. According to Emissions from the Cement Industry it is currently 50% of total emissions; I only addressed the other 50%. To which my answer is: "Just plant more trees!" If we terraform Earth with the equal numbers of trees to remove cement kiln chemical reaction CO2, then we should be OK, but I think there's a transport problem getting the CO2 to the trees. Maybe we can pipe it in to those new forests. Then, I'd look to removing the energy CO2 by using solar as I described.

The conveyer belts bringing in lime from the mines (all but 1 cement factory in the world get their lime from colocated mines (since it is (considered) uneconomical to do otherwise)) could run through tubes that carry the CO2 back the other way for a large part of the distance, reducing overall cost of transporting the CO2 to the man-made forests. Unfortunately, I don't think it could be mixed with the water misting systems to hydrate the terraformed forests, since that creates "Carbonic Acid". Nothing is free I suppose.

Some answers to that question:

Fast growing: CO2 (carbonic acid) uptake through roots? - GardenBanter.co.uk

http://www.treedictionary.com/DICT2003/shigo/RHIZO.html

The last link gets deep into chemistry. I haven't figured out if Carbonic Acid helps or not from that description, yet.