The Case for Energy Storage

"Gartner estimates that 3.1 million EVs will be sold between 2011 and 2015. That's 52MW hours of storage!"

3.1 million cell phones is 52 MWh.

3.1 million EV's is more like 52 GWh.

Hi avanderbom what did you use as basis for your per car storage?
When I use 24 kWh per car I get 74 GWh of storage, which seems conservative. By 2015, seems we will need to move into larger ev's Tesla already is up to 50 kWh. a delivery van or standard pickup truck could reasonably be anticipated at 100 kWh of storage.

Excellent article on Energy Storage. Renewables being intermittent,Energy Storage is the primary need.

Dr.A.Jagadeesh Nellore(AP),India

Generating Energy Storage & A Combination Renewable Energy System

Any renewable energy system that is installed should have extra capacity and be able to convert water into hydrogen which will be used to power a hydrogen generator as a back-up power source.

We should install a renewable energy system that utilizes solar & wind, when possible add geothermal to the mix.

A design is needed for a renewable energy system that can generate electricity and heat water with a step down mixer allowing the system to provide water hot enough for radiant heating and at the same time utilize a step down mixing valve to reduce the water temperature to be able its use for hot water in normal consumption.

A thermal renewable energy system may be able to provide both.

Prior to sizing up a renewable energy system, an energy audit should be conducted and energy efficiency recommendations should be implemented, that includes changing habits in utilizing energy and utilities in general.

Habitual changes can save between 20 to 50% of energy & utility consumption

YJ Draiman, Energy/Utility Analyst

chris,

I used the figure in Pete's article as basis. He's made an error and his figure is off by 3 orders of magnitude, that was all I wanted to point out.

No meaningful prediction can be made whether the real figure it is 52 or 74 or 26 or 150 GWh. There are too many variables at this point: how will the uptake of EV's be, how much time will they spend plugged in, will be allowed to act as storage, how will V2G technology progress etc).

One thing is sure: you can not assume that a 24 kWh battery offers a 24 kWh storage capability to the grid. Deep cycling is bad for your battery and should be avoided as much as possible. I would estimate the usable capacity for grid storage to be at most a third of nominal capacity. In case of a 24 kWh LEAF, that would mean 8 kWh.

The basic problem is energy storage is expensive, which is the basic problem of renewable energy versus fossil fuels. One thing I have wondered about is with minor subsidies, could you get large scale deployment of energy storage if you had a small UPS system that would keep a 15 amp circuit up for 2 hours (roughly 4 kwh). People might be willing to pay extra to know that in the event of a power outage, they would have lights and their refrigerator for a few hours.

@v-bruce-stenswick-62270

...and the combustion-based heating system with its circulating pump which, as I said elsewhere should also be cogenerating.

@christopher-lee

I am confused. I do not see any comments from you in this article.

v-bruce-stenswick-62270

The comment I referred to was in the discussion of the Bloom Box (fuel cell running on natural gas). It's in line with your statement on costs but extends it to small fossil-fuel heating systems, for which cogeneration is never an option.

3.1 million EVs (an optimistic number) times "the current crop of electric vehicles does not include the electronic inverters required to take power from the batteries and deliver it to the grid or building" equals no storage available to the grid at all. Some day there will be V2G technologies; that's the point at which it will make sense to start counting how much EVs can add to grid-level storage (and even then, it will have to be an opt-in thing, since some drivers may not want to start their day with empty batteries because local or regional electricity usage spiked the night before).

The comment regarding PV variability, "Clouds don't cause that much variability if the PV is spread out over a wide enough area" is true enough when considering the transmission grid, but not useful when considering distribution circuits - where most of the PV is sited.

San Diego Gas and Electric is reporting high penetration on their circuits, with 9 having more than 20% penetration. Their biggest concern is sunny, but not too hot, weekends, when PV generation can exceed load. Voltage swings of over 15% are being experienced, plus problems of thermal overloading due to the one-way flow of power built into distribution circuits. MW hours of storage will be necessary to smooth generation and shift to on-peak usage as the sun goes down but the load doesn't.

As a result, SDG&E is now including energy storage in their rate case.

More information is available here: http://www.drsgcoalition.org/news/media/2010-07-09-SGT-General_Interest.pdf

We sell the VRB(R) flow battery, and we think it's a good solution for integrating large amounts of solar PV.
More information on the VRB is at www.Utility-Savings.com

One area of research that needs to be followed closely is that of AmmoniaBorane. This relatively safe chemical shows potential for storage of Hydrogen (approximately 20% of the chemical's weight is Hydrogen molecules with about 11% retrievable) and recent develepments enable it to be recharged with hydrazine in liquid ammonia. Renewables can play a part in this by producing the electricity to produce hydrogen for recharging. Because AB is safe and hydrogen can be released from it and the spent fuel can be recharged, we could be looking at a closed system that would be completely renewable/reusable if wind solar or hydro etc are used to produce the electicity.

Bob,

Are you sure you're not mixing up the GWh's and MWh's? 52 MWh for 3.1 million EV's is ~0.017 kWh per EV.

I have to laugh when I hear that the utility is going to use EV batteries as "their" source of stored power. The batteries have a limited number of cycles and are one of the most expensive parts of the EV to replace when they "wear out". Why would any EV owner, in their right mind, give away battery cycles to the utility at the owner's expense? I think if they are going to do that then the EV owner should get more than just "avoided cost" reimbursement for that electricity. With all the inefficiencies of conversion, it is much higher than avoided cost and that all goes on the EV owner when he has to buy back more electricity to recharge the electricity the utility has taken out. Also, I'd be pretty angry if I had to go somewhere and the utility had drained my batteries or had only given me a slow half charge to serve the greater public good. I think storage should be part of each solar/wind facility when it becomes viable. If the utility needs storage to meet unexpected peak demands, then they should pay for it, not the EV owner. I think using EV's as storage is just the utility's way of "passing the buck" for their infrastructure onto EV owners. Don't let them do it "for free".

Bob_Wallace,

Regarding utilities using old batteries, I attended a presentation by Andrew Burke, of the Institute of Transportation Studies at the University of California-Davis. He's something of an energy storage guru.

http://www.its.ucdavis.edu/people/faculty/burke/index.php

He researched the capabilities of all potential car batteries and considered the requirements of utilities and the commercial opportunity for 2nd life. He saw a potential for 2nd use in solar PV, industrial back-up and some home uses, but saw huge barriers for utility use. Some of his concerns were the uncertainty of condition and cycle life of used batteries.


For example, who would test and certify the condition of used batteries for the utilities? Most lithium batteries bundle a sophisticated energy management system into the package. Who will test and certify that the package, which is designed for a certain battery capability, will not fail as the battery can no longer perform according to original hardware and software expectations? Thermal runaway (fire) is a huge concern for lithium, and the energy management system is key to managing that risk.


The variety of car battery technologies, configurations, vendors, driving conditions (hot or cold regions), etc., will make 2nd purpose difficult and expensive. The practical application will not be as easy as the theorists make it sound. I can send a copy of the presentation to you if you like.


Here's link to his earlier presentation in 2009. I saw the update in May 2010: https://www.soe.ucsc.edu/sites/default/files/micr-grid09-1.pdf

Utilities and grid operators should not take for granted they can discharge EV batteries whenever they like. EV discharges on demand should be priced multiple times higher than charging (ex, 14 cents/kw hour to charge, but $1.40/kw hour to discharge) because of the strain placed on the EV owners resource (unless utilities share in the capital costs of EV ownership). This price constraint will also insure EV's are only used when less expensive options are not available to meet demand.

Price considerations can be given to utilities (such as lowering of the discharge multiple from 10 to 5) if they provide homeowners 240v~480v home charging units free of cost, or provide free charging at public facilities and parking garages (ex, commuter rail stations, airports, hotels, municipal fleet garages, etc.) so long as there is a measurable net increase of charging sufficient for extended vehicle operation. Those numbers and agreements should be worked out in advance so that EV owners and utilities can know what energy resources are available to them and at what price.

In europe, no need for storeage. The grid is so big it is the
storeage system. Using solar, wind to all ends of the grid power is used (hopefully lowest cost), managed properly so no
need to store it. Like solar hot water, use it shut off gas
for a while (not used)and use gas when sun does not shine. Simple. Solar light uses less electrical power, wash dishes
at 2:00 AM when power is abundant. Hydrogen, fuel cells, PV,
wind, geothermal, conservation all together will make a difference. Solar Moore's Law for PV every 5 years PV will drop in price by 50%. Oil at $100.00/barrel so diesel electric power is not as competitive with PV electric. This is a big transformation but oil is now to expensive!

Hydro is so efficient, why don't we use solar and wind to pump water into a reservoir and generate the electricity when we need it? Just like the upper reservoir in Niagara Falls?

Here is the link for an article on Ammonia Borane:

http://www.rsc.org/chemistryworld/News/2011/March/17031104.asp

I think you will find it intersting reading

tim gard,

In many cases today, while the penetration of renewables is generally low, there is enough balancing available by throttling hydro plants.

Pumped hydro can not store that much energy. As an example: the Goldisthal facility in Germany can provide 1 GW for 8 hrs. You would need about a hundred of these to get Germany through 1 sunless night. Nights happen to be sunless on quite a regular basis ;) Never mind a few cloudy days.

The best option is a diversified mix of generating technologies. Storage is only the 2nd best option with today's technologies.

Having read some of the previous comments, I still think a case could be made for electricity storage at the level of individual dwellings, particularly if the package could handle more than one kind of small-scale power input.

The requirements are not the same as for portable or mobile power storage: weight is not a problem, and size not too much of a problem. Key requirements are reliability, long life, and safety for users and the environment.

What's available?

There is one big problem with the grid concept. Resistance. Over 50% of the energy we send to NY city here in NY from the Niagara, is lost into the air. When you start sending windmill current 500 miles because the wind is not blowing somewhere else, you had better be prepared to generate twice as much as you need! I have a neighbor who is working on an antigravity machine, but I am holding my investment. Concepts are seldom without major problems ... thats experience talking.

Hey Bob,

>Pumped hydro can not store that much energy.
Hydro turbine efficiencies are less than 15%. When you use elevated water to generate electricity with a 15% efficiency loss coupled with another 15% efficiency, the total loss is 97.75%. Now, if we could just get that dismal turbine efficiency up a bit higher ... 50% would be great. But if you study turbines closely you will see that 15% is the very best they can do because of accelerated mass issues.

High Voltage Direct Current (HVDC) enable the transmission of energy over long distances with little loss as compared to HVAC. Offshore windfarms will generally use HVDC for long runs of several miles and HVAC between windmills. An improved land grid should also include upgrading transmission for minimum loss.

Hi tim-gard-25916,

Are you saying that it takes 97.75 kWhr of electricity to get 2.25 kWhr out of a PH system? If so, please point me to some resources that I can review for more information. Thanks.

Yes Derek, but as Tesla noted, with a price. While much better than AC transmission, the cost of stepping up then down that high voltage is very high in equipment wear which must regularly be replaced as a result. Not to mention the massive heat losses. Transformers can not function without heat generation. Better, but still very wasteful. It was the reason, if you look, that Tesla choose AC over DC to begin with. Even if Edison showed 'how dangerous' AC was by electrocuting an old circus elephant in NY City! That Edison! What a guy! (True story!)

Crtoca,
It takes a bit of digging, but if you look at the total power being put into the grid in Niagara, follow to each step-up station, compare the 'in vs out' of each station and total them up, the numbers will give you the creeps. This has become an issue here in Western NY because the locals think all that hydro power should stay right here. (See Senator Maziars battle in Niagara County) Alas, the political strengths here in New York are heavily loaded at the East end of the state. They win and most of our electricity here in the West is generated with coal ... Its why we have the largest hydro system in the country but our rates are the second highest, after Hawaii.

OK Bob. You want to understand this? Then start from the beginning and forget this wiki nonsense. What is accelerated mass?

Because you do not have the basics yet. C&P? What about Bob. Is this too hard for you Bob? What is accelerated mass? In Bobs mind ...
I'm sorry Bob, I am running out of time. What is accelerated mass?

Listen Bob, I am sorry, but I have to get up at 5 AM, and sleep does not come easy. If you are willing to do your homework email me at dragmit@roadrunner.com and I will show you what you are missing. But this takes my time Bob. If you feel you are way too smart for this, then please do not waste my time.

To EnergySavers2: We have done extensive cost analysis of renewable energy storage. It turns out that solar-to-hydrogen-to-fuel-cells is the least expensive and most efficient of all the other storage methods. We have a contract to build a solar-hydrogen power plant in southern California
Eco-Engineers Corporation

One of the many inherent advantages of the technology offered by AAECorp.com is that long term energy storage is included at virtually no added cost. Contact AAECorp.com for more info.

Anon - Sorry, there is no way that solar to hydrogen to fuel cells is least expensive and most efficient. Solar PV is expensive to begin and adding fuel cells is another huge increase in cost. Plus, the efficiency losses are terrible. We've had our calcs confirmed by others at around 20-30% - solar to H2 to kWhrs from fuel cells.

We've looked at this strategy v. storage in a VRB(R) flow battery. The VRB is a big capital expense, not quite as bad as fuel cells, but much lower O&M cost. Efficiency is 65-75% depending on application. Much simpler operation, maintenance and installation and much better efficiency. And, wind to storage is the least costly. You can say I'm biased because I sell the VRB, but there is a reason I came to it. If you are doing cost analysis studies, then you should consider this as an alternative.

I don't know where folks are getting their pumped hydro figures from but to clarify some points I'll use a UK facility as an example.
The Dinorwig PH facility in North Wales (UK) has a capacity of 1.7GW and will run for 5 hours, i.e 8.5GWh of storage. Furthermore large turbines can be up to about 90% efficient and the over all efficiency of Dinorwig is about 80%. Another point about UK hydro is that all the large plants have now paid for themselves and produce electricity for about 0.25p (0.4¢)/KWh so this makes the cost of PH about double this.
On the point about size (Anne_van_der_Bom), ok 8GWh or so isn't a huge amount of energy but we are talking about current storage systems. The point about RE is that we are looking to the future and in that respect there may well be a number of sites that can supply large storage facilities and one such site, which is included in the DESERTEC proposal, is at Sebchat-Tah in Morocco which, if implemented, has a predicted capacity of about 1TWh (1,000GWh), there are other possible sites. Another possibility might be to convert existing large hydro plants, for example Hover (US) and Aswan (Egypt), into hybrid combined systems; Hover in particular is running at well below full capacity due to water shortage which might be alleviated by adding pumping. The storage capacity that could be added to these schemes is very large but how big a lower reservoir could be added I don't know, but if someone wants to pay me to do a survey it could be very interesting.

Nick!
<turbines can be up to about 90% efficient and the over all <efficiency of Dinorwig is about 80%

This is what I have been telling you ... you do not know where you are getting your figures from. This efficiency is ***without*** the accelerated mass losses ... your numbers are fudged!! Do the *full* math, not the 'engineered' numbers!!

Here's a suggestion: use existing geothermal technology to extract heat from hydo resovoirs. This would reduce the temperature of the water and thus the rate of evaporation or in other words maintain a higher level of water. These could be used in conjunction with floating solar thermal collectors placed on the resovoir which would absorb more heat before it hits the water. The energy collected could be used to generate the electricity used in the pumps for this system with excess pumping water back into the dam. the end purpose is to maintain a higher level of water in the resovoir not to produce electricity for the grid. That would be acomplished by th efficient hydro generators.

Here is an associated Press story in the Buffalo News this AM.
The US has 71,862 tons of spent nuclear fuel looking for a permanent home. More than the Yucca facility could hold had it been allowed to do so. And more on the way every day. Most of this stuff sits on site in spent fuel cooling ponds. This is great. And these idiots want to make more. Our ancestors will see us as the most foolish, selfish, uncaring people in the history of man, and they will obviously be correct. Anyone who uses these systems to generate profit should be responsible for its security for the next 10,000 years. Their children, not mine damn it!!

Biomass and trash are an excellent backup for wind and solar because when the wind doesn't blow and the sun isn't shining biomass and trash can be called on as a backup and their long term storage doesn't cost anything because leaving them lie on the ground until they are needed doesn't cost anything. We can convert trash and biomass to low cost energy using technology avaiable from AAECorp.com.

Regarding storage time for pumped storage, the figure of 8 hours probably pertains to the era when pumped storage was designed for daily cycling of nuclear off-peak to a typical peaking or intermediate duty. The new science of tailoring pumped storage for the purpose of renewable energy integration will call for different storage times. If the goal is merely load-following, it can be relatively modest - 8 hours of storage or less to get you through until off-peak recharge time. If the goal is turning wind into a firm capacity resource, then you need many more hours of storage. You can deign a plant to have 15, 20, 30 hours of storage (i.e., generating time), but you're trading off generating capacity if you have a fixed reservoir capacity. For PV solar, it's a bit different - less storage time needed unless you want to shift weekend production to weekdays, which can be of value in certain markets.

There are literally thousands of closed mining sites around the country. These flooded mines make excellent compressed air storage sites by 'simply' inserting large nylon reinforced balloons through drilled shafts down to the flooded mines, then pumping them with air created by elevated water pressure. The water in the mine will maintain the pressure at a regular rate until it is empty. Hundreds of thousands of these devices would provide all the energy storage we would need all year round and then some. Add to that the volume of piped air with local storage tanks simular to those used now for natural gas and lack of renewablw energy will never again be an issue

Well, Bob Wallace, I think it's worth keeping in mind that storage facilities actually do a lot more than just "storage." They can ramp up and down fast, providing the kinds of ancillary services that grids need; and they can, if they have enough storage time (like pumped storage and CAES) serve for peaking to intermediate level generation resources. When you look at the all-around versatility, you see that it's a much more valuable product than if they were just, simplistically, "renewable energy back-up". When playing that role as well, you get all of the above functions combined together. But each project's role has to be designed in efficiently. And, indeed, in order to get into the market today, bulk storage projects MUST be shown to be efficiently valuable or else they simply won't get built. This is the art and science of Gridflex Energy.

The variable pump/turbines used in newer PS extends the benefits of PSH. Below are the advantages of "in the process pumped hydro storage projects" being licensed at this time.The biggest obstruction for these projects is the utilities themselves, pumped storage replaces gas peakers at a 3 to 1 ratio. In other words each 100mws of PS replaces 300mws of combustion generation for the integration of intermittent generation. Utilities and gas companies don't like having their facilities become obsolete.
2. As regional assets these projects will provide numerous services including:
a. Congestion relief.
b. Additional generation capacity.
c. Additional transmission capacity (through redispatch).
d. Reserves.
e. Black start.
f. Voltage and frequency support.
g. Ramping services, both up and down.
h. Wind and solar firming and shaping (transformation and time shifting of variable wind energy into a firm dispatchable peak hour resource). Beyond the obvious advantages, CLPS supports future development of renewable generation. It is well-known that most renewable energy sources require federal and state subsidies to remain viable in the current market. CLPS will allow wind to retain Production Tax Credit (PTC) support without additional legislation.
Additional advantages of CLPS facilities are:
1. No fossil fuel consumption.
2. No CO2 or smog producing gas emissions.
3. Low installed capacity costs.
4. Low electricity price exposure.
5. Efficient use of groundwater: water is recycled between the two reservoirs, thus water requirements are limited to the initial fill and a small amount to make up for evaporative losses.
6. Significant-sized (grid-scale) projects, as compared to smaller battery and other storage technologies.
7. Contribution of jobs and taxes to local economies.
8. Supports wind and solar generation (RPS fulfillment).

9. Increases capacity value of wind.
10. Utilizes off-peak T&D capacity.
11. Provides a cost-effective, non-carbo

continued....
11. Provides a cost-effective, non-carbon alternative to use of gas turbines for "spinning reserves."
a. The use of quick dispatch, variable speed turbines enable pumped storage to provide ancillary services, including voltage support and regulation (load following, or second-by-second addition or subtraction of energy to or from the grid to match generation to load).
b. Ramping compensates for intra- and inter-hour changes in renewable outputs.
c. CLPS does not generate pollution when providing these 'capacity support' services in contrast to fossil plants which emit pollution even in standby mode.
12. Provides a 'soak' ready flexible market for instantaneous surplus and off-peak surplus electricity. Electricity can be delivered to the pumped storage system with no incremental transmission investment.
13. Wind and CLPS work together to provide an efficient generation system as seen in Table 1.
Wind State
Wind Turbine State
CLPS State
Normal
Generating: Supplying grid
Idle
Above maximum
Feathered
Generating: Supplying grid
Strong, above grid needs
Generating: Supplying pumps
Pumping
Weak or zero
Generating: Supplying grid or idle
Generating: Firming wind or replacing wind
Off-peak hours
Generating: Supplying grid or pumps (if grid is in surplus)
Pumping

V2G Vehicle to GRID it's not the total answer but adds a lot to the storage issue. Along with Solar PV, Wind, Geo-Thermal and hydro we should be able to run the world.
see V2G-101.com

Energy storage is expensive ... blah, blah, blah. Not really. Even the obvious kind, put electrical energy into a battery for future use, has a good ROI in TOU markets with demand charges. But energy storage is many other things. The simplest form of time shifting, which is a commonly cited need for storage, can be accomplished by simply leveling demand: this can be accomplished by simple technologies like insulation and low-E glass, hot-oil and ice HVAC buffering, etc. Hydro also supports virtual storage since it is generally limited in energy capacity but highly dispatchable (practical hydro capacity factors are low and seasonal i.e. there is a lot of headroom for supply regulation) - only consume the water when other renewables are insufficient. If pumping is necessary, consider a partly flooded mine: compact and nobtrusive with tremendously high head potential (more than 1 mile in some cases). 1000 m head == 2.7 kWh / cubic meter.