In their July 16th piece on solar energy technology in The New York Times, Andrew Revkin and Matthew Wald wrote that, "With more research, the solar thermal method might allow for storing energy. Currently, all solar power is hampered by a lack of storage capability." They are certainly right. In fact, a lack of storage capacity hampers a lot of things.
While there's been a lot of talk about coupling energy storage to solar (and wind) power, there are additional reasons for addressing our lack of storage capability. In fact, storage technologies can act as a "shock absorber" for the whole grid and can help address some of the key challenges facing the industry, including efficiency, reliability, and security. Simply put, energy storage is good for the grid.
The current electric power system is built around a central tenet: electricity must be produced when it is needed and used once it is produced. Bulk energy storage technologies break this antiquated linkage by allowing operators to produce and store electricity for later use -- as one would in other commodity markets.
Bulk energy storage also benefits all of us by creating a reserve that could be tapped in case of national emergency, much like the petroleum reserve. After all, our entire economy -- including our national defense capability -- runs on electricity. If key parts of the grid are taken out, and there is no electricity reserve at the ready, what happens then?
Emergency back-up power more often than not means diesel generators, and as we saw during the blackout of 2003, many diesel generators either couldn't get up and running or ran out of fuel before the lights came back on.
More specifically, however, storage benefits the energy consumer by providing a risk-management strategy, and it benefits the energy generator by making its assets more productive and efficient. As electricity demand continues to increase over time, existing generation assets must achieve greater efficiencies -- for both market and environmental reasons.
The amount of electricity flowing through the grid at any one point is determined not only by consumer demand but by physics as well. The grid itself requires a certain level of electricity flow in order to maintain its integrity. Ramping power up or down without taking grid requirements into consideration risks destabilizing the grid and costs money. So, during off-peak hours, coal facilities ramp down their utilization rate while nuclear facilities provide the baseload power needed to stabilize the grid. As additional power is needed, coal facilities are instructed to increase generation to meet demand. (Whether you like coal or not, by capacity coal-fired plants represent the largest fleet of power facilities). This process is called load following.
Coal plants follow the load requirements of the grid by ramping up or down as needed. The problem with this is that it wreaks havoc on coal plant systems, lowers overall efficiency, increases O&M budgets with additional maintenance, and results in shorter life spans of critical equipment.
However, if coal plants were not required to ramp down during off-peak periods -- nighttime -- but could instead continue to generate power and store it for release during the day, these facilities would not be required to perform as much of the load-following role as they currently do. Instead, power generators can provide power in long-duration (and more efficient) discharges and then use stored energy to provide low-cost ancillary services such as load following and spinning reserves. This would increase a plant's capacity factor, a measure of asset productivity, and reduce systemic stress and the costs required to address that stress. Utilized in this manner, large-scale storage helps offset the need for some additional peaking capacity, but is focused more as a system optimizer than generation replacement.
Coupled with storage, a generation facility can also gain much-needed flexibility during the critical scheduled "outage" seasons (when units are taken out of service for planned maintenance) of the spring and fall to avoid spot make-up purchases.
Other optimizing roles for storage include improving the economic and environmental profiles of fossil assets by reducing regular dispatch and cycling costs. Storage lowers the fixed-cost-per-unit output, improves the economics of these capital-intensive facilities, and helps them to run in a more efficient -- both operationally and environmentally -- manner that lowers overall per-unit production cost.
And, of course, coal facilities must also deal with their impact on the environment. Because emission limits (NOx restrictions, etc.) can constrain a power facility from operating maximally during peak times such as summer, they are often forced to operate at partial power. Unfortunately, when operating at partial power, plants are less efficient and have higher emissions per unit of heat input. Storage could help these facilities reduce their total emission per unit of output by shifting some production to the evening when the facility could run at its rated -- instead of partial -- generating capacity. And, by producing more power at night, air quality near the coal facility is improved since ozone-induced haze, a by-product of NOx, O2, and sunlight, is less likely to develop.
Wind: still enough to save the world
Why we overestimate the costs of climate change legislation
The faint silver lining of the Waxman-Markey clean-energy-mandates cloud
Comments View as Flat
David Roberts Posted 7:58 am
17 Jul 2007
Great post
grist.org
Permalink
Jon Rynn Posted 2:42 pm
17 Jul 2007
So, what are your favorite storage media?
...do you like pumped storage, a la Gar Lipow? Some other strategy?
Permalink
GreyFlcn Posted 5:40 pm
17 Jul 2007
Well,
I'm a pretty big fan of G2G battery storage.
(Yes, G2G, not V2G)
Permalink
Jon Rynn Posted 1:11 am
18 Jul 2007
How long before the batteries go dead...
...and how easy is it to recycle lithium batteries, or any others for that matter? Would we wind up with mountains of toxic dead batteries?
Permalink
ac5p Posted 1:30 am
18 Jul 2007
I thought coal energy was already stored
In the coal. Converting from coal to electricity then to something else and back to electricity in order to trade the ramping up & down of the coal plant for the ramping up & down of this other thing to improve efficiency and reduce pollution sounds good, but what is the proposal again and could it really work? I guess the real question is whether a carbon-less energy source could be used in a way that matches consumer demand. You can't ramp up solar when demand rises, you can't even use it after sunset. Wind has similar problems. What about nuclear? What about hydropower? Coal & gas plants aren't getting shut down until we have something clean that can ramp up to meet demand peaks at a time that is convenient for consumers, not producers.
Permalink
SustainableGreen Posted 2:35 am
18 Jul 2007
Big or Small Do It With Sustainable Sources
Hey, all:
Gee, it doesn't matter whether you speak of big or small. And sustainable sources are essential. You folks almost COMPLETELY ignore home systems and sustainability. And why the fuck are we STILL discussing COAL? Have you learned NOTHING about coal?
Are all of you STILL slaves to the mentality of electricity as a commodity? Are you lobotomized engineers (yeah, that's redundant!) with no ability for critical thinking?
Engineers + Box --> Nowhere
Greed will practically always drive utilities to confine sources into monopolies and customers into those sources. It is part of marketing. To the extent we follow their marketing crap we are doing no better.
Hey, Jon Rynn: I can only speak for lead-acid batteries since this what I use at home, and I vetted them years ago. These are highly recycled (as highly as any consumer product) by customers and suppliers. Plastic, lead, acid all get reused. I suspect it is a matter of scale--the larger the battery the easier the handling and the better the incentive to recycle. It may be that large new-tech batteries should only be leased to customers (whether utility or residential), so the suppliers have better control over recycling.
Wind and Sun on all scales, with storage on all scales, is the way to sustainability--on all scales.
David
Sustainability For Life
Messages done with sustainable energy, with Wind and Sun!
Permalink
Jon Rynn Posted 3:00 am
18 Jul 2007
Sodium-Sulfur batteries?...
...look like a winner, according to this USA Today article, but I don't know anything else about the technology:
Permalink
Gar Lipow Posted 4:23 am
18 Jul 2007
For meaningful comparison
For meaningful comparison you need to know kWh capacity.
The USA today article describes them as costing $2,500 per KW. But the question is: per KW for how long? IF that $2,500 for a ten hours capability, that $250 per kWh of capacity. If it $2,500 for one hour then it is $2,500 per kWh of capacity. I suspect the real figure lies somewhere in that range. Maybe someone with some time can do some more research and come up with a cost per kWh cost. As Rynn says, storage helps stabilize grids. It is useful to all energy sources.
Permalink
Kristina & Jason Makansi Posted 5:01 am
18 Jul 2007
storage technologies
Interesting link on the PG&E research. We are big fans of the idea of utilizing "recycled" batteries to form storage banks. Besides using storage banks in electric utilities, there is a real need for storage in high-tech industries such as telecommunications and data centers and in manufacturing facilities that must have 24/7 high quality, reliable energy. The stored energy helps to combat short-term voltage sags and can operate in a peak-shaving role for the manufacturing facility. Flow batteries (such as vanadium redox, zinc bromine, and others) all have potential in these areas. Flow batteries are also attractive because they don't appear to have any problems with fast and frequent charging and discharging and they are "long lived."
In fact, the potential scalability of flow batteries to 100 MW facilities could create a commercial storage option between large-scale bulk (pumped hydro and CAES) and smaller scale distributed systems. Just five years ago, at least two companies (Regenesys-no longer in business and VRB Power Systems) were hard at work blazing this trail. While some of these are in use today, additional demonstration facilities for newer systems have been proposed around the country, but, as with many things in life, getting the job done requires dollars that are often in short supply when it comes to storage.
We see very few prospects for pumped storage because of permitting issues. There hasn't been a pumped storage facility permitted since the early 1980s. The only other "bulk" storage technology ready for primetime is CAES. In a recent post (http://gristmill.grist.org/story/2007/7/7/152836/1112/#6), we discuss CAES and TCAES further.
In terms of other types of storage, there are:
-SMES (superconducting magnetic energy storage) which, although expensive, can be effectively used for grid stability and for preventing voltage sags at manufacturing facilities;
-flywheels are primarily used in the auto and aerospace industry, but are being considered for power delivery in the 500kW range. Flywheel systems are attractive because they are compact and have lower maintenance costs and requirements than battery systems.
-thermal energy storage. This is not a new idea and, in its ice-based form, is already widely used. The other format, using molten salt as the medium, is in development.
As for lead-acid batteries mentioned above, they're attractive because they have relatively high storage efficiency and low capital costs. But these batteries require tender loving care when integrated with power electronics, because they require constant charging to ensure that you use the maximum life of the battery. Lead-acid battery-based storage systems are designed for slow, deep cycle discharges of between 50-80%. Generally speaking, a lead-acid battery has about a 4-year life cycle under normal operating conditions, and because their usefulness is affected by response time, discharge rate, temperature and life cycle costs, their ability to serve broad energy management applications has been limited. (FYI: we strongly support distributed energy and distributed storage systems.)
By the way, a couple of years back we put out an extensive "state-of-the-art" Executive Briefing Report titled, Energy Storage: The Sixth Dimension of the Electricity Value Chain, on the technologies, their applications, and their market potential. We still have a few left over that are available at a steep discount. If you're interested in one, let us know.
Pearl Street/Jason and Kristina Makansi Learn more and order Lights Out at http://www.jasonmakansi.com/lightsout_endorsements.html
Permalink
Jon Rynn Posted 5:03 am
18 Jul 2007
The electricity storage association...
...has a nice graph comparing various storage options, although I'm not absolutely sure how to read the graph -- it seems to indicate that Sodium-Sulfur batteries are in a range between $1000 and $3000 per KW, but from about $500 to $1000 per KWh, if I'm reading it correctly. The Technology/Capital costs page is here and if you go here and click on the thumbnail, they have a summary of different methods, including pumped storage.
Permalink
Jon Rynn Posted 5:13 am
18 Jul 2007
Thanks for the info...
...and I also just want to throw in to the mix the idea that, in the future, a sophisticated use of different storage and generation strategies will require a larger workforce dedicated to energy; it will be a different world then the present one of most energy management occurring in centralized locations, with much more work being done locally and on the ground. That kind of work would definitely beat flipping burgers, me thinks.
Permalink
GreyFlcn Posted 6:48 am
18 Jul 2007
I'd rather we do
I'd rather we do coal electricity for our transportation than biofuels/hydrogen.
Depends. And Depends. I will say however that from what I've heard not only is it possible to recycle lithium batteries, but people will most often pay you for the extractable lithium resources.
As is, lead acid battery recycling rate is about 98% so battery recycling is not a problem.
As for the battery life that all depends on what type of lithium battery, and how many other batteries you link in parrallel.
Apparently wiring multiple batteries together results in longer overall battery life.
However when the battery is dead for transportation purposes, it's still got 80% of it's charge life left on it.
For a LOT of specs on the nextgen lithium batteries, perhaps you might want to read or listen to this:
http://www.autobloggreen.com/2007/05/07/autobloggreen-qan ...
All in all I've heard of lithium car batteries lasting from anywhere inbetween 10-40 years.
Permalink
Kristina & Jason Makansi Posted 7:50 am
18 Jul 2007
storage article
We just received energybiz magazine in the mail and it has a short article on storage in which you all may be interested. It's not in-depth, but it illustrates what, according to the authors (two EPRI guys), a utility system based on storage technologies might look like. You can read it here:
Energy Storage Breakthroughs: An evolving technology for managing the grid
Pearl Street/Jason and Kristina Makansi Learn more and order Lights Out at http://www.jasonmakansi.com/lightsout_endorsements.html
Permalink
Colin Wright Posted 3:50 pm
18 Jul 2007
Not made in China ... yet
I noticed too that the Sodium Sulfide batteries were invented in this country, but now are imported from Japan. Another example of how the various US administratiions have taken their eye off the renewable ball in favor of cosy-ing up to various Middle Eastern oligarchies.
Permalink
GreyFlcn Posted 2:51 am
19 Jul 2007
Thats the trick though
I don't believe V2G is going to have much impact.
Instead I think G2G will be far more important, since it allows for full control by the utility.
It also doesn't have car consumers wearing down their precious battery life while they can still use it.
And for those car holders, if they sell the battery after it's no use to them. Not only are the utilities getting cheap batteries, but the car consumers are getting a lower cost of ownership.
Permalink
CADJOCKEY Posted 7:39 am
26 Jul 2007
Energy Storage
The VRB Energy Storage System (VRB-ESS) http://www.vrbpower.com
Check this technology out. It seems to good to be true
Permalink
Gar Lipow Posted 12:58 pm
26 Jul 2007
VRB Energy
It is not too good to be true. You just need to read the FAQ. They give a minimum price for truly large scale use of their product at between $350 and $300 per kWh. (It goes up and down, maybe with the price of some key ingredient, but always within that range.) That maximum price for a long time has been at $600 per kWh. That is a reasonable price for certain purposes, but very high for an all renewable grid.
See: question 11 at
http://www.vrbpower.com/technology/faqs.html.
Yes I know it says "The incremental cost of storage for large systems is approximately $170 per kWh." But I wrote them for clarification, and they told me that in multi-gigawatt sizes that might get them down to $225 or $250, but not below that, and they were not that confident of the $225 or $250 number. VRB is a really great product. And there is tons of stuff it is good for. It can let you replace spinning reserves with operating reserves. It can add reliability to the variable power sources, even without letting them move all the way forward to become baseline sources. It can store small amounts off off-peak power for peaks use. If you read the website you can see other uses. But it is not yet true large scale mass storage in the sense of holding ten hours or so worth of power - nor does it pretend to be.
Permalink
amazingdrx Posted 12:20 am
27 Jul 2007
Interesting perspective
We need more of this energy industry insider perspective to hone our arguments.
How to move the debate around to storage/conservation now? With an internet enabled grid that stores energy in the form of heating/cooling in everything from your home freezer to the thermal mass of malls.
For instance,cool a mall's floor down (using geothermal cooling that uses a fraction of the energy of air conditioning, that's conservation) during hours with lowest power demand and coast on that cooling for the next 24 hours (that's storage), right through the peak demand time.
Since building heating/cooling produces 36% of our GHG emissions,and large scale wind could provide 95% of our grid power already, this indicates there is more than enough buffering capacity in heating/cooling alone to dispense with other storage.
This is without adding the effect of charging plugin vehicle batteries off peak and doing large scale industrial heating/cooling in such a way as to smooth the grid. Like recycling glass during off peak grid time and using the waste heat to generate power during the peak.
With an internet enabled grid energy use would be timed over the whole grid to make electrical storage of power unecessary. Even in a 100% wind/solar powered grid.
Now how to make industry insiders like the authors of this article realize and incorporate this information about an internet switchable grid into energy policy? Show them it is the bottomline profit path of the future.
Then utilities will race to compete in this area, with customers all connecting their various high energy use heating/cooling devices through switches that are controlled by the smart grid. Eventually plugin vehicles will connect through these switching systems too.
These authors are the ones to convince. But will they interact on revolutionary concepts like this? Hard to say.
http://amazngdrx.blogharbor.com/blog
Permalink