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OKIsItJustMe

(19,933 posts)
Thu Mar 28, 2013, 03:10 PM Mar 2013

Discovery opens door to efficiently storing and reusing renewable energy (electrolyzing water)

http://www.ucalgary.ca/news/utoday/april1-2013/discovery-renewable-energy
[font face=Serif][font size=5]Discovery opens door to efficiently storing and reusing renewable energy[/font]

By Mark Lowey

[font size=3]Two University of Calgary researchers have developed a ground-breaking way to make new, affordable, and efficient catalysts for converting electricity into chemical energy.



Trudel, assistant professor of chemistry, says their work “opens up a whole new field of how to make catalytic materials. We now have a large new arena for discovery.”

The pair have patented their technology and created from their university research a spin-off company, FireWater Fuel Corp., to commercialize their electrocatalysts for use in electrolyzers.

Electrolyzer devices use catalysts to drive a chemical reaction that converts electricity into chemical energy by splitting water into hydrogen and oxygen fuels. These fuels can then be stored and re-converted to electricity for use whenever wanted.

…[/font][/font]
http://www.ucalgary.ca/news/utoday/april1-2013/discovery-renewable-energy/backgrounder
http://dx.doi.org/10.1126/science.1233638 (Doesn’t work yet.)
http://www.sciencemag.org/content/early/2013/03/27/science.1233638.abstract
28 replies = new reply since forum marked as read
Highlight: NoneDon't highlight anything 5 newestHighlight 5 most recent replies
Discovery opens door to efficiently storing and reusing renewable energy (electrolyzing water) (Original Post) OKIsItJustMe Mar 2013 OP
More from the article. GiveMeFreedom Mar 2013 #1
Don’t worry about it “being bought out and forgotten.” OKIsItJustMe Mar 2013 #3
No, work on electrolyzers continues Yo_Mama Mar 2013 #7
See post 6 kristopher Mar 2013 #8
That is a very significant development Yo_Mama Mar 2013 #2
You’re welcome! OKIsItJustMe Mar 2013 #5
They expect large units for sale in 2014, and prototype home units in 2015 bananas Mar 2013 #4
A question for OKSensei kristopher Mar 2013 #6
(Who is OKSensei?) OKIsItJustMe Mar 2013 #9
When it comes to fuel cells you are, of course. kristopher Mar 2013 #10
It's a different technology! Yo_Mama Mar 2013 #12
The primary objection to using hydrogen for energy storage is cost OKIsItJustMe Mar 2013 #13
This level of analysis doesn't account for costs associated with developing infrastructure kristopher Mar 2013 #17
You mean you don’t want it to be meaningful OKIsItJustMe Mar 2013 #20
This version of the chart spells it out better OKIsItJustMe Mar 2013 #21
Here are results from a 2012 study for the Navy OKIsItJustMe Mar 2013 #14
So what is the answer to the question? kristopher Mar 2013 #16
Really!? OKIsItJustMe Mar 2013 #19
Direct cost of platinum is only ONE problem associated with a hydrogen SYSTEM kristopher Mar 2013 #22
I’m not saying any of those things OKIsItJustMe Mar 2013 #23
Actually you are very carefully saying nothing - you STILL haven't answered the question. kristopher Mar 2013 #24
Fatally flawed math OKIsItJustMe Mar 2013 #25
Yes, it is an obviously contrived example kristopher Mar 2013 #26
I love that “exceeds 90%” (it sounds so much better than 91%) OKIsItJustMe Mar 2013 #27
That's a different technology Yo_Mama Mar 2013 #11
The amount of energy lost in the storage process is a key element of cost. kristopher Mar 2013 #15
fuel cells tend to wear out quadrature Mar 2013 #18
Batteries also tend to wear out OKIsItJustMe Mar 2013 #28

GiveMeFreedom

(976 posts)
1. More from the article.
Thu Mar 28, 2013, 03:21 PM
Mar 2013
Electrolyzer devices use catalysts to drive a chemical reaction that converts electricity into chemical energy by splitting water into hydrogen and oxygen fuels. These fuels can then be stored and re-converted to electricity for use whenever wanted.

The only byproduct from such a ‘green’ energy system is water, which can be recycled through the system. To store and provide renewable power to a typical house would require an electrolyzer about the size of a beer fridge, containing a few litres of water and converting hydrogen to electricity with virtually no emissions, the researchers say.


If this is true, I see it being bought out and forgotten. Almost to good to be true.

OKIsItJustMe

(19,933 posts)
3. Don’t worry about it “being bought out and forgotten.”
Thu Mar 28, 2013, 03:30 PM
Mar 2013

There are a number of teams pursuing this line of research.

One of them is Daniel Nocera’s team:
http://vimeo.com/8194089

Yo_Mama

(8,303 posts)
7. No, work on electrolyzers continues
Thu Mar 28, 2013, 03:53 PM
Mar 2013
http://www.popularmechanics.com/cars/news/industry/4212844

The catalyst is so important because getting the cost down is paramount. Once you get the cost of hydrogen down, the pre-existing fuel cell technology becomes REALLY useful:
http://www.mnn.com/earth-matters/energy/stories/first-hydrogen-fuel-cell-for-the-home

This is a subject of huge interest not only to individuals or companies, but also to governments. For example, Germany's problems with the Energiewende could be hugely lessened by such an advance.

Yo_Mama

(8,303 posts)
2. That is a very significant development
Thu Mar 28, 2013, 03:25 PM
Mar 2013

Thanks very much for the links - and all the breaking tech links you post.

OKIsItJustMe

(19,933 posts)
5. You’re welcome!
Thu Mar 28, 2013, 03:35 PM
Mar 2013

Much as many would like to think otherwise, I believe “clean technology” is our only hope.

bananas

(27,509 posts)
4. They expect large units for sale in 2014, and prototype home units in 2015
Thu Mar 28, 2013, 03:34 PM
Mar 2013

"The company expects to have a commercial product in the current large-scale electrolyzer market in 2014, and a prototype electrolyzer – using their new catalysts – ready by 2015 for testing in a home."

kristopher

(29,798 posts)
6. A question for OKSensei
Thu Mar 28, 2013, 03:48 PM
Mar 2013

Last edited Thu Mar 28, 2013, 04:53 PM - Edit history (1)

They tout their advantage by saying their catalysts "are 1,000 (of) times cheaper" than those now on the market while being at least as efficient.

What is the current level of round trip efficiency being seen with this process in current products?

ETA: Is this article reasonably accurate?

Electric round-trip efficiency of hydrogen and oxygen-based energy storage
International Journal of Hydrogen Energy (February 2005), 30 (2), pg. 105-111


An electrolyzer and a fuel cell have been integrated in a small-scale stand-alone renewable energy system to demonstrate that hydrogen can be used for long-term stationary energy storage. The economic and environmental performance of such a system is strongly related to the ability of the electrolyzer to convert electrical energy to hydrogen and the ability of the fuel cell to convert hydrogen back to electrical energy, which together define the round-trip efficiency of the hydrogen storage system. One promising way to improve the efficiency as well as to decrease the capital costs of the fuel cell is to recuperate the oxygen from the electrolyzer and use it as the fuel cell oxidant instead of compressed air. This paper presents the modifications made to the system in order to implement oxygen recuperation. The round-trip system efficiency was found to be 18% with oxygen recuperation and 13.5% without it.

http://journals2.scholarsportal.info/details.xqy?uri=/03603199/v30i0002/105_ereohaoes.xml


If this is reasonably accurate it means that this process has very limited use as a storage medium since the electricity it produces would be about 5X the cost of the input energy without yet counting the cost of the system itself.
It seems probable that the technology in batteries for EVs will be more competitive. Of course, efficiency improvements could be in the hydrogen cycle's future, and battery technology may not deliver on the cost reductions that are anticipated. We'll have to wait and see.

OKIsItJustMe

(19,933 posts)
9. (Who is OKSensei?)
Thu Mar 28, 2013, 05:09 PM
Mar 2013
http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/30535aw.pdf
[font face=Serif]Proceedings of the 2001 DOE Hydrogen Program Review
NREL/CP-570-30535

[font size=5]LOW COST, HIGH EFFICIENCY REVERSIBLE FUEL CELL (AND ELECTROLYZER) SYSTEMS[/font]

[font size=4]Technology Management Inc.
9718 Lake Shore Boulevard
Cleveland, Ohio 44108
216-541-1000
tmi@stratos.net[/font]

[font size=3]Abstract

A reversible solid-oxide fuel cell (SOFC)/electrolyzer system capable of storing electrical energy generated from renewable sources at projected round-trip efficiencies over 80% and providing backup power generated from propane at efficiencies over 60% (LHV) was studied. The systems perform all electrochemical functions using a single stack assembly with a unique systems design that stores both gases and thermal energy. Total system capital and operating costs are projected to be lower than an equivalent lead-acid battery with a backup generator system. This work was a follow-on to experimental work funded under NASA SBIR Phase I and II programs.

Introduction
Grid-independent electric power systems using renewable power sources (such as solar, wind, and water) can potentially drastically reduce CO2 emissions while offering siting flexibility and economic advantages. Cost is the major barrier to the practical use of systems of this type. Because power is generated intermittently and is variable -- the nature of renewable generation -- such systems typically require both a large energy storage capacity and a backup generator. Practical choices to meet these requirements are deep-cycle lead acid batteries for storage plus an engine generator. While batteries can achieve high energy storage efficiencies near 80%, the battery/generator combination is quite expensive (first cost plus maintenance costs). In addition, current generators using internal combustion technology are highly polluting, noisy, and have low fuel efficiencies.

Fuel cell technologies are described in the 2001 DOE Hydrogen Program Annual Operating Plan as "cost effective, highly efficient, and critical for overall success in the Hydrogen Program Strategic Plan." As shown in Figure 1, fuel cells serve as both a transitional technology -- as the world moves away from fossil fuels, and as an end point technology -- for the efficient production and utilization of hydrogen.

…[/font][/font]

kristopher

(29,798 posts)
10. When it comes to fuel cells you are, of course.
Thu Mar 28, 2013, 05:20 PM
Mar 2013

So we have two wildly different numbers. The paper citing 13.5-18% is from 2005, and the one citing 65-80% from the hi-temp SOFC is from 2001.

Where does the technology described in the OP fit into that information?

Yo_Mama

(8,303 posts)
12. It's a different technology!
Thu Mar 28, 2013, 05:42 PM
Mar 2013

The OP is about PRODUCING hydrogen.

The efficiency of the fuel cell in which you use the hydrogen is another matter.

If the cost of hydrogen generation can be brought low enough, current fuel cell tech is more than sufficient to allow replacement of some fossil fuels for heating, esp. for combined power and heat apps.

There is a jackload of info available here:
http://www1.eere.energy.gov/hydrogenandfuelcells/production/

kristopher

(29,798 posts)
17. This level of analysis doesn't account for costs associated with developing infrastructure
Thu Mar 28, 2013, 07:12 PM
Mar 2013

Last edited Thu Mar 28, 2013, 07:57 PM - Edit history (1)

I don't think it is meaningful at all in addressing the question at hand since that relates to how the new technology will affect the amount of generation required to move from fossil fuels.

OKIsItJustMe

(19,933 posts)
20. You mean you don’t want it to be meaningful
Fri Mar 29, 2013, 09:26 AM
Mar 2013

Did you actually look at it?

Independent Panel Water Electrolysis Cost Estimate

• In 2009, DOE convened an independent panel to assess the cost of producing hydrogen using water electrolysis

• The Panel investigated current, state-of-the-art electrolyzer technologies including technology advances that would result in reduced capital costs or improved conversion efficiency

• The Panel estimated that, using 2009 technology, the plant-gate cost for hydrogen produced from electrolysis in a centralized facility using renewable, wind-based electricity would be $3.00/kg (expected range from $2.70/kg to $3.50/kg)

• The Panel estimated that, using 2009 technology, the cost for delivered hydrogen from electrolysis for a forecourt refueling station would be $5.20/kg (expected range from $4.90/kg to $5.70/kg)

OKIsItJustMe

(19,933 posts)
14. Here are results from a 2012 study for the Navy
Thu Mar 28, 2013, 06:18 PM
Mar 2013
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA562618



1.2 Background
Navy underwater vehicle platforms (UUV, ASDS, SWCS, etc.) are demanding larger and larger energy storage capacities to accommodate longer underwater missions and increased platform power requirements. New energy storage devices with high volumetric energy density for underwater vehicles, both manned and unmanned, are therefore needed, such as regenerative fuel cell (RFC) systems based on proton exchange membrane (PEM) technology. An RFC consists of a fuel cell powerplant, an electrolysis system for recharging the reactants, and reactant storage. These water-based energy storage systems have been shown to perform substantially better than traditional battery systems in areas such as rechargeability, specific energy density, and reliability. Advanced membrane and catalyst materials will enable higher efficiency electrolysis, substantially improving the practical energy density for regenerative fuel cell applications.





kristopher

(29,798 posts)
16. So what is the answer to the question?
Thu Mar 28, 2013, 07:08 PM
Mar 2013

What technology does the OP specifically refer to when they say they meet the current level of efficiency?

This isn't a loaded question, I don't know the answer. But I do think it is a significant question that should be addressed with specificity before we get too excited. If it is a reasonably high level of RT efficiency then it is good news indeed. If it is for a system with low efficiency then it may only be laying groundwork for something more meaningful at a later date.

OKIsItJustMe

(19,933 posts)
19. Really!?
Fri Mar 29, 2013, 09:13 AM
Mar 2013

Quick! What metal can you think of that is 1000’s of times more expensive than the metals they are using, and is typically used for catalysis?

http://en.wikipedia.org/wiki/Electrolysis_of_water#Efficiency

… Platinum alloys are the default state of the art for this oxidation. Developing a cheap effective electrocatalyst for this reaction would be a great advance …

kristopher

(29,798 posts)
22. Direct cost of platinum is only ONE problem associated with a hydrogen SYSTEM
Fri Mar 29, 2013, 10:38 AM
Mar 2013

As you well know I'm asking about the efficiency of the technologies being discussed in the two articles we have above - One pegs the RT efficiency of the SYSTEMS as described in the OP as between 13.5% and 18%. You posted one that talks of SOFCs having an efficiency of up to 80%. The Navy tests showed a RTE of 38-42%.

Are you claiming the system described in the OP can deliver a ROUND TRIP EFFICIENCY of 80%, or are you saying it is 40% - or is the 2005 assessment correct at 18%?

It is also glaringly obvious that you are attempting to avoid the issue of amount of infrastructure society will require by trying to use cost/watt as a metric - and even then you are putting your thumb on the scale by not including lithium batteries.

To emphasize my reason for concern I'll repeat wrote elsewhere:

Say I have a 4kw solar system and a storage system that is 100% efficient which meet my needs with 15% extra capacity on average. If the storage system is 20% efficient what happens to the amount of solar I need to install to achieve the same objective?

It increases 5X and I now require a 20kw system.

The same principle applies on a national scale.

OKIsItJustMe

(19,933 posts)
23. I’m not saying any of those things
Fri Mar 29, 2013, 12:07 PM
Mar 2013

However, it is clear the numbers you cite, “The round-trip system efficiency was found to be 18% with oxygen recuperation and 13.5% without it.” are, at the very least, out-of-date. The study I cited used a closed system (the Navy really doesn’t want to be supplying oxygen to the power system in a submerged vehicle) and it didn’t use lots of exotic new experimental equipment:



In developing technology for air independent undersea vehicle missions, a ground-test breadboard system was adapted and utilized to prove advanced components that enable closed- loop, zero emission, low signature energy storage. The system utilizes proton exchange membrane (PEM) fuel cell and electrolysis technology with proven commercial reliability, and a balance-of-plant primarily consisting of commercial-off-the-shelf (COTS) components. Objectives included refurbishment of the system to improve operability, including upgrading the power capability of the system to take full advantage of the rated stack power. The results of cycle testing at increased output power included demonstration of 34 consecutive cycles. Initial durability testing measured the magnitude of reactant loss to the ambient atmosphere, before replacing components known to contribute to this loss as observed during tests in a previous program. Advanced components to mitigate these losses were designed and tested at a bench-top level before integrated testing within the breadboard system. A final round of cyclic testing was conducted with advanced reactant circulation during fuel cell power generation as well as complete hydrogen recovery during the electrolysis recharge period. A model of a refined system package and the demonstrated electrochemical performance predict that 400 Wh/L is achievable in the near-term.




As for me “putting a thumb on the scale” please, take it up with NREL or the Navy.


What are these infrastructure costs I am ignoring? What do you suppose it would cost to use lithium ion batteries for grid storage?

http://www.nytimes.com/2011/10/29/science/earth/batteries-on-a-wind-farm-help-control-power-output.html
[font face=Serif][font size=5]Batteries at a Wind Farm Help Control Output[/font]

By MATTHEW L. WALD
Published: October 28, 2011

[font size=3]ELKINS, W.Va. — Another wind farm opened on another windy ridge in West Virginia this week, 61 turbines stretched across 12 miles, generating up to 98 megawatts of electricity. But the novel element is a cluster of big steel boxes in the middle, the largest battery installation attached to the power grid in the continental United States.

The purpose of the 1.3 million batteries is to tame the wind, but only slightly, according to the AES Corporation of Arlington, Va., which developed both the wind farm, known as Laurel Mountain, and the battery project.

The installation is far too small to store a night’s wind production and give it back during the day when it is needed, or to supply power when the wind farm is calm for more than a few minutes. Instead, AES says, the battery will be a shock absorber of sorts, making variations in wind energy production a little less jagged and the farm’s output more useful to the grid.



But the batteries are so small — somewhere between C and D batteries in size — that the wind farm, at full power, would fully charge them in about 15 minutes. Even at a peak demand time, the energy stored would only be worth a few hundred dollars.

…[/font][/font]



I wonder why the study I cited didn’t include lithium-ion batteries…


http://gigaom.com/2011/04/29/5-things-you-need-to-know-about-energy-storage/
[font face=Serif][font size=5] 5 Things You Need to Know About Energy Storage[/font]

Apr. 29, 2011 - 12:25 PM PDT

[font size=3]…

3. Costs Vary Greatly: The cost of installing various types of storage systems depend on their size, duration of storage, efficiencies and how they are used. When looking at megawatt-scale storage systems to support hours of storage, the cheapest option is by compressing and storing electricity underground. Compressed air technologies cost between $960-1250 per kilowatt, or $60-125 per kilowatt-hour. In some scenarios, advanced lead acid battery system can be the most expensive, at $4600-$4900 per kilowatt or $920-980 per kilowatt-hour.

For frequency regulation by grid operators, who will want short bursts of energy and therefore a storage time measured in minutes, the least expensive choice is lead acid batteries, which cost $950-$1,590 per kilowatt, or $2,770-$3,800 per kilowatt-hour. Lithium-ion batteries follow with $1,085-$1,550 per kilowatt, or $4,340-$6,200 per kilowatt-hour. Flywheels are the most expensive, at $1,950-$2,200 per kilowatt or $7,800-$8,800 per kilowatt hour.

Lithium-ion batteries are among the most expensive choice for utilities that want storage to help them manage the grid and for industrial/commercial applications.

…[/font][/font]

kristopher

(29,798 posts)
24. Actually you are very carefully saying nothing - you STILL haven't answered the question.
Fri Mar 29, 2013, 01:08 PM
Mar 2013

What is the round trip efficiency of the system the process in the OP is related to?


As for the cost issue, you are going to great lengths to misinform and you really do your fellow DUers a disservice with your effort.

The study you cited isn't complete, it doesn't include lithium.
Cost per delivered watt under the assumptions in that study isn't a measure of the effect the storage option has on national scale generating infrastructure requirements. I don't know how significant those consequences would be with H vs Li but I do know you are doing everything possible to obstruct discussion of that point.

As for the cost discussions in your most recent post, they are not relevant at all since:
1) the use cycle over the life of batteries would introduce strong additional economic considerations that add great value to the battery side of the equation. Batteries for EVs will still have 75%+ of their usable life remaining after they have served their function for transportation, a factor which would dramatically reduce their cost for stationary energy storage applications; and
2) the dual use role (grid storage and storage for propulsion) of both systems under a Vehicle to Grid economic paradigm isn't considered.

I'm sure your objective is to enable a transition away from fossil fuels as rapidly as possible, so your cavalier indifference to the fact that we could absolutely need to build significantly more generation with hydrogen than with batteries is perplexing.


OKIsItJustMe

(19,933 posts)
25. Fatally flawed math
Fri Mar 29, 2013, 01:46 PM
Mar 2013
Say I have a 4kw solar system and a storage system that is 100% efficient which meet my needs with 15% extra capacity on average. If the storage system is 20% efficient what happens to the amount of solar I need to install to achieve the same objective?

It increases 5X and I now require a 20kw system.

The same principle applies on a national scale.



  1. There is no such thing as a 100% efficient energy storage system.
  2. As we have seen, hydrogen is not limited to a 20% round-trip efficiency (let’s call it approximately 40% cutting your solar requirement in half)
  3. Why would anyone work exclusively from stored energy (which is what your scenario assumes.) Solar typically works best during daylight hours, when electricity demands are highest. During that time, demands will be met primarily (if not exclusively) with electricity being generated at that moment (no storage needed.) In theory, excess power will be stored for night (or dark days)

kristopher

(29,798 posts)
26. Yes, it is an obviously contrived example
Fri Mar 29, 2013, 03:26 PM
Mar 2013

Designed to force you to focus on the issue.

You make a valid point about the proportion of storage that serves load, and I'll build on that single, lonely example of your cooperation by reminding you of the recent analysis of the PJM service area showing that the most cost effective scenario they found is that this region works best with a significant amount of "excess capacity" instead of large amounts of storage.

http://www.sciencedirect.com/science/article/pii/S0378775312014759

It is important to note that this grid level study stands in stark contrast to the off-grid example I used, highlighting the fact that regional variations in the resources are going to have a strong impact on how significant the point I raised eventually becomes.

BTW, round trip efficiency for advanced modern batteries easily exceeds 90%.

OKIsItJustMe

(19,933 posts)
27. I love that “exceeds 90%” (it sounds so much better than 91%)
Fri Mar 29, 2013, 04:47 PM
Mar 2013
https://docs.google.com/viewer?a=v&q=cache:f1qal67VeLwJ:ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060008706_2006006323.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEEShISJWZ46-wRajEZUC_iEFOIksg_8toui9w9UjvGa3D7Qo8MQ84lJOXUGu7hs40Z3r4v-K0ztscQsGsR0oi_coP7iddcLA0pRxV8c_f8oHINslbWPZ_SttBnAzI3A0ni_c3pCyk&sig=AHIEtbSJeK7R4Aq8PQUis0psSkm-QQJ1Zg
[font face=Serif]…

January 2006



[font size=5]Round Trip Energy Efficiency of NASA Glenn
Regenerative Fuel Cell System[/font]

Christopher P. Garcia, Bei-jiann Chang, and Donald W. Johnson
QSS Group, Inc.
Cleveland, Ohio 44135

David J. Bents and Vincent J. Scullin
National Aeronautics and Space Administration
Glenn Research Center
Cleveland, Ohio 44135

Ian J. Jakupca
Analex Corporation
Brook Park, Ohio 44142

[font size=4]Abstract[/font]

[font size=3]NASA Glenn Research Center (GRC) has recently demonstrated a Polymer Electrolyte Membrane (PEM) based hydrogen/oxygen regenerative fuel cell system (RFCS) that operated for a charge/discharge cycle with round trip efficiency (RTE) greater than 50 percent. The regenerative fuel cell system (RFCS) demonstrated closed loop energy storage over a pressure range of 90 to 190 psig. In charge mode, a constant electrical power profile of 7.1 kWe was absorbed by the RFCS and stored as pressurized hydrogen and oxygen gas. In discharge mode, the system delivered 3 to 4 kWe of electrical power along with product water. Fuel cell and electrolyzer power profiles and polarization performance are documented in this paper. Individual cell performance and the variation of cell voltages within the electrochemical stacks are also reported. Fuel cell efficiency, electrolyzer efficiency, and the system RTE were calculated from the test data and are included below.

[font size=4]Introduction[/font]

The hydrogen-oxygen RFCS has been promoted as one of the most favored energy storage technologies for solar electric power in aerospace applications, mainly due to its high (300 to 1000 Whr/kg ) specific energy. A RFCS could provide much higher specific energies than any advanced battery system and potentially the highest storage capacity and lowest weight of any non-nuclear device. Due to irreversible heat generation the RTE, that is, the fraction of energy put into the system that actually gets delivered back to the user, is limited to about 75 percent.

Round trip efficiency is one of the most important attributes for the user since it dictates, along with the energy density, how much storage media, or storage installation size, will be required in order to accommodate user energy demands and how much power from the primary source will be required to replenish that storage. For many mechanical, and some magnetic and electrochemical storage devices, the round trip efficiencies can be as high as 80 percent. However, they do not compete with the RFC on energy content per unit weight basis.

Performance estimates made for recent hydrogen oxygen PEM RFCS conceptual designs have predicted round trip efficiencies of roughly 50 to 60 percent depending on stack polarization performance and current densities applied. This paper presents electrochemical stack performance and round trip energy storage efficiencies from closed cycle hydrogen-oxygen PEM RFCS which is being operated as an energy storage device at NASA GRC.

…[/font][/font]

Yo_Mama

(8,303 posts)
11. That's a different technology
Thu Mar 28, 2013, 05:33 PM
Mar 2013
http://www1.eere.energy.gov/hydrogenandfuelcells/applications.html

Fuel cells are already cost competitive for some applications! They will become much more so if the cost of the hydrogen can be brought down.

kristopher

(29,798 posts)
15. The amount of energy lost in the storage process is a key element of cost.
Thu Mar 28, 2013, 06:55 PM
Mar 2013

Say I have a 4kw solar system and a storage system that is 100% efficient which meet my needs with 15% extra capacity on average. If the storage system is 20% efficient what happens to the amount of solar I need to install to achieve the same objective?

It increases 5X and I now require a 20kw system.

The same principle applies on a national scale.

 

quadrature

(2,049 posts)
18. fuel cells tend to wear out
Thu Mar 28, 2013, 08:01 PM
Mar 2013

there is always something to go wrong.

the catalyst gets poisoned.
the structure crumbles with use.
it gets clogged up.
etc

OKIsItJustMe

(19,933 posts)
28. Batteries also tend to wear out
Fri Mar 29, 2013, 05:48 PM
Mar 2013

The question is, is their useful life long enough for the application?

http://en.wikipedia.org/wiki/Fuel_cell

[font face=Serif]…

[font size=4]Forklifts[/font]

[font size=3]Fuel cell powered forklifts are one of the largest sectors of fuel cell applications in the industry. Most fuel cells used for material handling purposes are powered by PEM fuel cells, although some direct methanol fuel forklifts are coming onto the market. Fuel cell fleets are currently being operated by a large number of companies, including Sysco Foods, FedEx Freight, GENCO (at Wegmans, Coca-Cola, Kimberly Clark, and Whole Foods), and H-E-B Grocers.

Fuel cell powered forklifts provide significant benefits over both petroleum and battery powered forklifts as they produce no local emissions, can work for a full 8 hour shift on a single tank of hydrogen, can be refueled in 3 minutes and have a lifetime of 8–10 years. Fuel cell powered forklifts are often used in refrigerated warehouses as their performance is not degraded by lower temperatures. Many companies do not use petroleum powered forklifts, as these vehicles work indoors where emissions must be controlled and instead are turning towards electric forklifts. Fuel cell forklifts offer green house gas, product lifetime, maintenance cost, refueling and labor cost benefits over battery operated fork lifts.[/font]

…[/font]
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