Are rock batteries a "Breakthrough in Energy Storage"?

More on Pumped Heat Electricity Storage here: http://www.greentechmedia.com/articles/read/breakthrough-in-utility-scale-energy-storage-isentropic

A research project, sodium sulphur batteries, but the largest bank of batteries nonetheless.

http://www.energy.ca.gov/releases/2010_releases/2010-02-09_battery_storage.html

I'll have to read up on Isentropic.

Very open and willing to give hard numbers on performance.

I give high marks for credibility.

the transition from a "proof of ignorance" prototype to a functional heat pump that works between 500 C and -150 C at the eff's listed is a pretty big challenge.

There is a huge gap between the prototype and a functioning heat pump and system. I'm not saying it's not a great idea or it's unworkable, only that the company has a long way to go to be commercial.

You seem to be talking completely out of your ass.

bookmark this thread and PM me in a year to see how far this technology has grown.

Then we can discuss which ass is doing the talking.

If you had it you would have produced it instead of resorting to a dodge.

debate with you the merits of a prototype that is way short on information and lots of blue sky predictions (probably trying to generate capital) and its viability as a commercial endeavor.

I simply offer you my opinion (BTW, I'm a mech engineer)

If don't like my opinion? So what, you will surely get over it.

You are like the Republican Party right now - you have an agenda (the promotion of nuclear power) and you want anything that threatens that agenda (successful renewable technologies) to fail.

What is wrong with reminding people that there is a long way from prototype to actual and real proliferation of a technology. Especially of this sort.

A LOT of people have tried to solve this problem for a long time. To think that this story (which is mainly a funding request) represents something that will be reality shortly is slightly beyond hopeful.

But I hope they are right. Solving energy storage issues is one of THE key issues for the viability of eco friendly energy harnessing solutions.

That's Kristopher's middle name. Heck... you may be in violation of a trademark.

As soon as someone has an idea that may some day be a small part of a greener future (regardless of specifics), he'll latch on to it. 24 hours later it's a viable option and we can expect it to solve our problems within a few years.

Nothing wrong with a little optimism... but a dash of reality would help season the mix.

Same thing with proposals for green energy. One favorable article and he can't believe that anyone would question this new consensus of all scientists everywhere. Particularly funny when one contradicts another that he was spamming the week before... but free entertainment is one of the benefits.

Now if we could harness THAT for stored power... :)

LARED (1000+ posts) Click to send private message to this author Click to view this author's profile Click to add this author to your buddy list Click to add this author to your Ignore list Sat Oct-25-03 10:00 AM
Response to Reply #1
4. Just wondering

do you avoid things like television, dental x-rays, smoking, or airline flight. All this activities will increase you exposure to radiation.

I can never understand the angst some people have regarding nuclear energy. It's clean, it's pretty cheap, has an excellent safety record when compared to existing viable energy technologies. (Before I get flamed; "green energy" is not really viable as an energy source that could meet significant demands in this country. I am for applying these technologies where it makes sense but realistically the capacity is small.)

As for the problems with waste? Give it time. The technologies will emerge to deal with it. But there is no reason to wait for these technologies prior to building new nuke capacity. The waste streams of fossil fuels are far dangerous and presently have a far greater impact on peoples heath right now that radioactive waste ever has.



OP here: so how did that hydrogen thing this post attaches to work out for you? By 2003 it was clear that hydrogen had no hope of competing due to the poor system efficiencies, distribution problems and obstacles to the development of fuel cells.

So you are jsutifying nuclear then because it is a great source of hydrogen which is an obvious attempt at greenwashing, and now you are trying to undermine a breakthrough technology for renewable storage.

And we should trust your and the bagginses opinion because...

You think I can undermine a new technology by posting on DU?

Good one. I'll be sure to tell my wife after I get the US nuclear program back on track.

BTW it's a bit creepy to dig up a post from nearly seven years ago, just to call me a shill.

You have a clear agenda so frack off.

engine. It's just a bit creepy and paranoid that you found one post (I guess) and you have determined I am a shill, out to undermine all technologies other than nuclear.

I, for instance, am a huge fan of wind and solar generation and can't wait for legitimate long-term storage options to make them viable for a larger portion of future generation capacity...

Unfortunately... I also live in reality and recognize that we are quite a distance from achieving that. Since I'm unwilling to accept that we can have the entire world fossil-generation-free in the next 20 years (and since I have no irrational fear of nuclear power), I'm obviously a shill.

Of a breakthrough in green technology, and would like to wait to see results,

You're a shill.

At least to K

It's a failing of mine.

...have no particularly special passion toward energy issues, other than to support what smart people tell me to support....

...and even I think you come off sounding like a hyper-reactionary loon in this thread.

OMG THIS BRAND NEW TECHNOLOGY STILL IN POOF OF CONCEPT STAGE WILL SAVE THE WORLD TOMORROW, AND IF YOU ARE SKEPTICAL ABOUT THAT YOU ARE A LOSER SHILL POO POOH HEAD!

As a more or less neutral party on stuff like this (except for opposing nuclear power expansion) I gotta tell you, if you think this is how you convince people you are sorely mistaken. You could be completely right and I'm so turned off by your hyperbolic nutty that I'm not listening anymore.

So nice job. :eyes:

Which is, same difference as far as my point goes.

An energy conversion or storage system has a theoretical capacity, but getting that energy out rarely meets that threshold. Thus car engines are somewhat inefficient because they don't recover all the energy stored in the gasoline, nuclear reactors don't get 100% of the energy theoretically available from splitting the atom, solar panels don't convert all the energy in sunlight to electricity, and so on. to believe that the theoretical capacity of a system is going to be fully available is naive, that's why engineering is hard. this sounds like a good system, but it's a mistake on your part to assume it's a sure thing.

They are very explicit - a round trip efficiency of between72-80%. The poster you refer to has no basis on which to dispute that claim. Neither do you. The company claims only a small increase in isentropic efficiency (<10%). That's it. That is the totality of their mechanical innovation. Their genius is the very concept itself - it is a breakthrough like sliced bread; we had knives, we had bakery bread, but it took a while before someone put the two together to fill a need. The idea that this isn't a well understood technology is total bullshit.

Here is the situation:

What is the difference between energy storage and energy generation? If I have a gallon of gasoline I have X amount of energy stored in a container. If I have a charged lithium battery pack I have X amount of energy stored in a container.

If I need to use this energy for something I have to convert it to power. An internal combustion engine converts the solar energy stored chemically in the gasoline to heat and mechanical energy. The heat is largely wasted and losses to heat accounts for 70-88% ff the gasoline's energy.

If I use fuel cell, I have to run the gasoline (or natural gas etc) through a "reformer" and change the nature of the stored energy from one chemistry to a different chemistry. This results in lost energy, but now I can use a fuel cell to process the chemical energy into electricity and heat. Total losses for process in the fuel cells now on the market are around 60-80% of the energy contained in the gasoline. For the Bloom box the loss is stated to be 52%.

Another term to be familiar with is "energy carrier". That describes the portability characteristic that is associated with liquid fuels, but you should remember that liquid fuels are really stored energy. While the portability factor is the one most people focus on for gasoline, it's important to bear the fact that it is stored energy in mind because when we seek an alternative to gasoline, we are dealing with both the storage issue and with the portability issue. I can store a lot of energy cheaply in a pumped hydro system, but I can't carry that around in my car.

So the application is very important when evaluating these technologies. In the case of fuel cells, the efficiency of the fuel cell with a reformer is better than an internal combustion engine, but it still emits a lot of CO2. We can get the portability but we are using stored energy in fossil fuels and that means CO2.

An alternative is to operate a separate process that uses electricity (from fossil, renewables, or nuclear) to produce pure hydrogen. Of course, that incurs an energy loss from whatever energy state we begin with. The H2 then must be made portable. That incurs another loss. When pure H2 is used in a fuel cell, the conversion efficiency is about 50-60%, meaning we lose 40-50% as heat. But when we look at the process of getting the H2 to the fuel cell.

The alternative for automobiles (where portability is important) is the use of lithium batteries. When we track the same route for energy made portable by storage in lithium batteries as we do for fuel cells, this is what we find. Starting with 100kwh of electricity, for the two methods of making H2 portable for the fuel cell we end up with between 19-23kwh pushing the vehicle down the road; starting with the same 100 KWH for batteries we end up with 69kwh pushing the vehicle down the road - it is simply no contest.



From "Why a Hydrogen Economy Doesn't Make Sense" at http://www.physorg.com/news85074285.html

This chart is 4 years old, so there are some improvements on both sides of the chart, but there is nothing that has been developed that alters the basic relationship that strongly favors batteries.

If we look for applications outside the transportation sector, we need to ask how relevant the portability factor is. If we are looking for a system for our home, business or local housing development, what are the characteristics the system must possess to best meet our needs?

I'd argue that the first point is that it should be carbon neutral. If we are not concerned about carbon, the present grid system is pretty darned good at meeting our energy needs for home use. But if we move to carbon free energy what then? The use of nuclear power fits into the present grid system so we can make the transition by building an additional 400-500 nuclear plants in the US and changing nothing else. To use that strategy throughout the world will require about 17,000 nuclear plants.

The vast majority of independent energy policy analysts do not see that as a viable strategy for a number of reasons. There are quite a few plans for making a transition away from fossil fuels and very few from outside of the nuclear industry advocate for expansion of our nuclear fleet. The particulars of that argument are not relevant for this discussion about applications for energy storage and recovery within a distributed grid system, which would be built around renewables. If we go with the nuclear option, the use of fuel cells from any maker have little value.

So (presuming you are interested in a transition to renewables) what about using fuel cells to meet needs at the home, business or local housing development level?

At the home level the chance seems fairly low since the same efficiency issue with input is at play. In our chart above, we find the answer at the level above the end use level for we want to compare the output of the device delivering the electricty, not what the final efficiency through our refrigerator might be, right? The chart gives us an efficiency range of 21-26% for the fuel cell and 77% for the lithium batteries.

If we go to larger scale systems we are looking at the same issue, only the battery is different. For transportation lithium is best because it sores a lot of energy by weight and volume compared to other types of batteries. But for these stationary applications in the microgeneration range, there are other batteries that are very functional.

What about biofuels? They also have to go through a reformer for the fuel cell and when they do, the fuel cell compares poorly to combined cycle gas turbines in the area of efficiency.

The bottom line is that with a fuel cell because you have to go from electricity, to chemical and back to electricity, the system efficiency is too low. If we look at using the fuel cell with hydrocarbons, then it must go through the reformer, and that is even worse than if we manufacture H2.

If we use of manufactured H2 from renewable sources we have essentially no carbon carbon emissions. But there is still the low efficiency rating. We can use the same no carbon renewable sources with batteries of all sorts much more efficiently.

That's why the low cost, scalable rock battery at 72-80% round trip efficiency that can be used anywhere is a breakthough and why a new iteration of an old design of the fuel cell isn't.

http://www.greentechmedia.com/articles/read/breakthrough-in-utility-scale-energy-storage-isentropic

"Just doing a few calculations, using rock as a thermal storage seems practical, assuming a reversible heat pump and motor/generator could be built without substantial round trip loss. The 70% quoted is comparable to pumped hydro, and better than some schemes."

"One m3 of granite has 240kWh of thermal energy with a 400degC change, or 60kWh with a 100degC difference. So building 10x10x20m with a pair of insulated gravel boxes as described above could store 30MWh of electric energy (assuming 30% thermal-electric heat pump conversion with 300degC temperature swing/side—or just 100degC for 30MWh thermal). With R38 insulation, heat loss would be less than a few percent per day."

"The gravel is a cheap medium for energy storage—only around $1/kWh of daily storage (the gravel would only be a small part of the overall plant cost). It also doesn’t require a huge amount of space—a (California) household would only require a half cubic meter of gravel to store a days worth of energy."

"I wonder if smaller units would be practical, e.g. would a 10-100kW heat engine (50-500kWh/day) and 1-10m3 storage be practical? If so, then it would be practical for commercial buildings. Power could be purchased at night then used during peak times during the day, and the price differential would pay for the equipment."

"At a large scale, I can see how 100m long storage buildings could be constructed at a power plant without consuming substantial area. Instead of 30GWh, just 5GWh could store peak use for a 1GW power station (nuke plant size) at 100x150x15m."

"That also brings to mind—is there an advantage to connecting a heat pump directly to the shaft of a wind or steam turbine, or feeding thermal energy directly into the rock? Instead of rotating a turbine, converting to electricity, then feeding that to a motor to run a heat pump, how about a direct mechanical link?"

"What is the time-lag to starting up a heat pump engine? If it just a matter of metering air flow and just seconds to ramp up/down, then this technology would be usable for grid stabilization and as an alternative to inefficient peaker turbines. With only 30% round trip loss for storage of efficient combined-cycle power plants, the overall efficiency of converting fuel to on-demand electricity with this method is better than simple-cycle peaking plants."
- Carl Hage

http://www.greentechmedia.com/articles/read/breakthrough-in-utility-scale-energy-storage-isentropic

Could it become one? Sure (although the "battery" that gets us to a much greener future must hold days worth of power, not hours)...

...but to be a "breakthrough" one much actually have... dare I say it?... a breakthrough. Something more than a potentially good idea with an early prototype.

And no... don't try to tell me that in five years all wind plants will have this as an option.

Making false statements on an internet forum isn't going to change the dynamics a work.

This is a significant technology.

A "technology" has to involve actual working models larger than something that fits in a garage.

You have to actually DO something at least ONCE before you can call it "significant".

Of course... I can see why you would feel that way... it gives your POSTS a shot at significance (by the same fantasy standard). :)

But I've build several myself (of other devices).

Appears to be very cost competitive, if it works.

And it's scalable, can work for a home, a neighborhood, a city, a utility...

It is one thing to look at a prototype of a fusion system that *might* produce a flash more energy than it consumes, it is another to build a prototype of a well known and proven heat pump design that is tweaked a bit for a few extra points of efficiency.

The *breakthrough* is the genius of the concept.

Oh yeah... just last week when you were telling us how wave generation was just a few years from commercial viability because it was essentially off-the-shelf technology.

All the while ignoring the fact that the first commercial installation of a wave-energy farm broke down after about a month of use and still isn't back up over a year later.

There really are a wide array of extremely good technologies just sitting on the shelf waiting for someone to connect them to a profitable application such as energy storage or harnessing the energy in a wave or the current in the Gulf Stream.

You are so married to the Technocult of nuclear power that it is nearly driving you mad to be faced with the reality that the world is going to leave that monstrosity behind for sunlight, wind, and waves.

Must be an imaginary shelf.

world is going to leave that monstrosity behind for sunlight, wind, and waves.

Not until significant storage issues are dealt with. And even with the most optimistic reading, this isn't it.

But it's certainly worth pursuing. Could really help bridge the gap.

before I start proclaiming genius or breakthrough

The cold fusion guys had a "breakthrough."

I think we all know how that worked out.

Or considering, maybe not.

:silly: :dunce:

I prefer to see results before proclaiming genius or breakthrough

I'm pretty convinced a gas cycle heat pump that operates between 500 C and -150 C might actually be pretty esoteric.

...you just spin it faster.

Yeah... that's the ticket.

You have to understand that K. has a very... um... "unique" understanding of "off the shelf".

The greater the range of temperature the more efficiently the pump operates, the trick has been to make them work with only a 40 degree spread.

When you read an article about the next great thing... and it turns out that the company has (for instance) half a dozen employees and was founded by a hedge fund manager...

...and they're looking for some investors to fund their next step (which means that they couldn't even pass the smell test with the venture capitalists)...

...you should at least pause for a moment before deciding this solves every problem.

I'm a big fan of "algae oil" as a possible future fuel... but I still have to recognize that making it work is still a massive IF... not a "when".

you mean that article was part of a strategy trying to find some funding?

...that article (mentioning funding for this group) is a few months old. This is someone else following up on the story.

But that's when he latched on to them. It also isn't the only example of the phenomenon for him.

From last May:

For now, Isentropic’s energy storage benefits are still just company intentions. It’s been building out two demonstrations of its technology and is looking for $5 million to help construct a larger, commercial-scale demo project. Last year Isentropic raised a Series A round from Credit Suisse Securities Europe and won a £250,000 ($380,112) research grant from The Carbon Trust; Wagner says so far the company has raised about $1 million. Next week at the Energy Storage Association conference in Washington, D.C. Isentropic will be discussing its technology and showing off its designs. It’s a good time to jump into the U.S. energy storage market, which, as we pointed out this week, is just starting to get attention from Congress, investors and entrepreneurs.

but other than that, there's no reason why this wouldn't work.

OTOH, there's a better way to work this. Instead of using the gravel bed to generate electricity, why not put one at a factory and use it as a boiler? Most factories use steam for SOMETHING. (I was going to say "all factories" but then remembered there are a LOT of factories that don't use steam.) They use gas, oil or coal to fire the boilers. If you're running a renewable-energy source of electricity like a wind turbine to heat your rock bed, your steam generation suddenly becomes a LOT greener--no fuel, no CO2.

It is certain that storing electricity to run plug-in hybrids is sexy and all the rage, but industry is likely to adopt a PROVEN technology like this real fast because industry's energy costs are extraordinarily high. We have a tire plant in Fayettenam. Last I heard, their energy bill is $12 million a year--yes, one million dollars per month to power the plant. Half of it goes into steam generation. You come in with a rig like this and tell them, x, y and z factories are using this and their energy costs have been cut in half. This system costs $2 million. They are going to tell you to bring one by and put it in because if this thing will eliminate the cost of generating steam they will pay down the system in four months.

Have you thought that you might not have the uderstanding to evaluate the "efficiency numbers"?

At least, that is what I have to conclude from the rest of your post. You are suggesting that we:
take electricity from a renewable source;
turn it into heat;
make steam with the heat;
use the steam to power a generator.

I'm not trying to be harsh, but can you see where that might seem wasteful to some people? Wouldn't it be better to just send the electricity you use to make heat out over the wires directly?

The efficiency numbers of the process are well within the capabilities of known technologies. Their improvement in the conversion to and from heat is only a few percentage points. I said earlier their genius isn't in the fact that they've built a better machine, but that they had the idea to use this machine for this particular application by hitching it to a pile of rocks.

I'd suggest you take this idea in to your company's facility manager and ask him how much they could save by putting in one of these so that they could buy all of their electricity at the late night rate and store it for use the next day. See if he thinks it is a good idea. Be sure to take the chart from the article at the OP link showing comparative costs of storage technologies.

From Wikipedia



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

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html

How will I ever survive your soporific wit?

What did you do there? teach how to color within the lines?

:rofl:

If we're running a canned food plant, we'll use steam heat to cook the food.

In a tire factory, steam heat cures the tires, heats the molds, melts the rubber.

Steel mills use it as a source of motive power--instead of running compressed air or hydraulic pumps to drive linear piston actuators, they'll use the steam they already have.

I could go on but you get the point: steam is a normal source of energy in most factories. They BUY their electricity--unless they have some sort of cogeneration facility on site, like a wood products mill that burns bark and sawdust for steam and generates electricity from part of the steam, but that's getting unpopular; it's better and less polluting to sell the bark and sawdust to a paper mill then buy electricity with that money.

The reason I don't like the efficiency numbers is no one else is converting heat to electricity with that kind of efficiency. You're looking at 55 to 60 percent efficiency for any kind of electrical generation on a GOOD day. Wiring has resistance, mechanical devices have resistance...from http://cleantechnica.com/2008/06/26/electricity-generation-efficiency-its-not-about-the-technology/ the president of Recycled Energy Development says power plant efficiency is 33 percent--same as it was in 1957. This article: http://www.wise-technology.com/Heat-Pump-Energy.html works with 60 percent efficiency. The guy believes 75 to 85 percent efficiencies are "not unrealistic." I believe that's a "perfect world" condition, assuming new and low-resistance wiring, bearings not gaining mechanical resistance by collecting crud, etc., etc., etc. I could be nice and split the difference, but I really think over the lifespan of this thing you're not going to see more than MAYBE 50 percent efficiency. You're storing heat in rocks. Rocks will not give up all their heat. This makes them nice if you're using heat AS heat--steam, facility warmth, whatever--because it ensures a constant supply of heat, but if you're putting energy into a rockbed so you can get it all back and turn it into electricity, it's not so nice. Let's use 50 percent efficiency as our baseline.

Let's play with the idea of storing electricity purchased at off-peak rates for use in on-peak times. We fall into the "large general service" category--less than 10,000 kW used. I think we're about 7000 kW--we're not making anything and our heat is gas, so we're just running lights and refrigeration. We pay a $200 per month basic facilities charge, a $10.10 per kW demand charge (at 7000 kW, that's $70,700) plus 4.2 cents per kilowatt-hour. Now let's assume we had one of these storage systems big enough to store enough power to run the place all day. We pull 185,000 kWh a day directly from the lines--7000 kW x 24 hours for constant demands, the rest for exterior lighting at night. At 4.2 cents per kWh, that's $7770 per day to the power company. Total power bill is the $500 facilities charge plus the $70,700 demand charge plus the $7770 per day energy charge...so, $304,300 for a 30-day month, $312,070 for a 31-day month, and $288,760 in February.

Putting in a rockbed storage device is going to up our power draw considerably. I assume you wouldn't pull electricity out of the rockbed storage during off-peak hours, and we'll say those are 12 hours per day. So we're powering the shop for 12 hours on it, requiring 84,000 kWh. If we get 50 percent efficiency (unless someone manages to invent the perpetual motion machine in the next three weeks you're not getting 85 percent, and you wouldn't get it for long anyway) we need to pump 168,000 kWh into it. Add 168,000 kWh to the 101,000 kWh we're running directly off the powerlines (we need more power at night because the parking lot lights are on), and our total power draw has gone up to 269,000 kWh (meaning a 22,416 kW load). The city charges 3 cents per kWh to large industrial users on time-of-use plans, so our daily power bill is now $8070--an increase of $9000 per month. There is an "excess off-peak demand charge" of $2 per kW. It's calculated by subtracting the on-peak load (which, in this case, does not exist) from the off-peak load which is 22,416 kW. So...22,416 kW x $2 per kW excess demand charge comes to $44,832--a savings of $25868 on demand charges. So let's see...$500 facility charge plus $44,832 in demand charge plus $8070 per day, which comes to $287,432 for a 30-day month ($16,868 savings), $295,502 for a 31-day month ($16,568 savings) and $271,292 for February ($17,468 savings).

So far it looks pretty good. We're not done yet. Now amortize the probable $20 million cost of a rockbed storage system the size of our parking lot over a 25-year lifespan. (Putting a huge heat source under the parking lot will have the benefit of eliminating snowplow services, but since I live in North Carolina where that's not a real issue, we'll leave that out. The people who live in Minnesota would have a much different number here. It would probably be more than that to completely tear out the parking lot, put a rockbed under it and repave over the rockbed, but we're just throwing numbers around here.) That works out to $800,000 per year or $66,666 per month--let's say $66,500 so we don't scare the evangelicals. Subtract the $16,568 savings on the electric bill in a 31-day month from the $66,500 cost of having this thing in the first place, and it turns out we are going to pay almost $50,000 ($49,932 to be exact) to store electricity. Somehow I think my facility manager wouldn't think much of a suggestion that would raise the light bill $50,000 per month. (The rates I used are good for my area--http://www.faypwc.com has them.) Okay, 25 years down the road you're looking forward to $17,000/month savings assuming the electric rates do not go up, but it will cost you $15 million to get there.

Now go back to my initial suggestion of forgetting this crazy electric storage shit and generate electricity by wind, use the wind power to heat a rockbed, use the rockbed to generate steam and use the steam in all places where steam itself is customarily used. Now you've got a totally different situation. We don't use steam at work so I can't give you any numbers, but if you pay half a million dollars a month to generate steam with natural gas and a system that will generate an equivalent amount of steam costs $6 million with a $1000/month maintenance expense for the turbines and heat exchangers, people will line up around the corner to get it. Now payoff is a little over a year, and after that happens you'll be generating all your steam for the year for what it now costs to generate it between midnight and 6pm on one day.

Your response was uncalled for.

The efficiency they are talking about is in the reversibility of the heat storage.

In essence you might use 4 mWh to pump 2mWh worth of energy into the storage - and they then say that their method can get a large percentage of the 2mWh out again. If I understand it correctly.

Which is of course fine if it would otherwise be energy wasted (or not created) - and is cheaper than just creating new energy.

Someone correct me if I am wrong - which I might very well be.

It's a heat pump when storing energy (as heat), and then a heat engine when using that stored heat energy to produce electricity.

The thing about heat pumps is that they move heat energy from one place to another (refrigerators and air conditioners are heat pumps too), but against the normal flow of 'from hotter to cooler'. And they can move more heat energy than they consume from their power source. For instance, a heat pump that consumes 1MWh of electricity might move 2MWh of heat energy from the cold 'tank' to the hot one (there's also the question of where the 1MWh of energy dissipates to; it may be something like: cold tank loses 2 MWh of heat, 1 MWh of electricity is used, 0.5 MWh dissipates as heat energy into the environment, the hot tank gains 2.5 MWh of heat).

When they reverse their pump, and turn it into a heat engine, they are saying they will be able to get perhaps 0.8MWh of electricity back out of the process of moving the heat energy (2 MWh, 2.5 MWh or whatever) from the hot tank back to the cool one.

I think that the temperatures this company proposes working with are lower (the -150C) and higher (the 500C) than usual (certainly far outside the temperatures used for normal space heating or cooling). I expect this will produce a lot of engineering challenges (working with a wide temperature range normally does), but I can't see anything that would stop it in theory. Their working fluid is argon, which makes some sense - it's a noble gas (that makes up about 1% of the atmosphere, so is, I think, the cheapest) which is inert, and so won't corrode the machinery, and is a gas all through the temperature range they're working with. See also http://www.timesonline.co.uk/tol/news/environment/article6493372.ece

Heat pumps may well become the typical way to heat buildings in the future; you get more heat energy, at a temperature suitable for heating air, than you put in as electricity - the heat coming from the ground around the building (which then just draws more heat from the surrounding ground and air). This would allow electricity (whether produced by nuclear, solar, wind etc.) to heat buildings far more efficiently than via heating coils.

"Isentropic's technology is compact, has no geographical constraints and claims a round-trip efficiency of 72 to 80 percent."

Round trip efficiency includes all energy returned from the process rated against all energy input into the process. This compares favorably to pumped hydro which has a round trip efficiency of around 75%, but the rock battery has fewer limitations.

They pay a million a month for power. Half of it's steam generation, like I said. The rest is electricity.

There will be one in every house. Next to the Mr. Fusion and the Rosie-model personal android.

For one thing, the timing for large scale rollout of this technology is not here yet. We need to focus on deploying renewable generation and improving energy efficiency, and government policy is largely reflective of that. As the penetration of wind and then solar increases and the carbon costs escalate to the point where they have a more substantial effect on the existing natural gas generation facilities, there will be larger and larger call for dispatchable solutions that allow the capture of spilled energy from renewable facilities.

That will depend on two things, the price they set for carbon and the natural market economics that work on renewables.

It is, however, a very good technology to watch. I say technology instead of company because as noted, this company's stroke of insight was to match an existing technology to a new application. Lots of people are looking at a lot of different iterations of proven technologies to see if they can find a new market for old ideas and this is one. Another is the use of home heating systems as a means of energy storage. The idea for that is that if a large number of homes use some form of electric heat powered by remnewables and if the heating system stores energy like the rocks, then you can "top them off" during periods of high production and use that as a buffer for the system demand during cold weather.
What that means is that there are probably going to be a lot of competitors coming out with similar systems long before demand is strong enough to pick the market winners.

But the idea is kick ass.

Storing heat in rockbeds to heat a home is a very accepted technology, but getting the heat from electric is absolutely the wrong way to do it. Try this instead: Make real thin water tanks out of some kind of metal--aluminum would be fine--and put them right up against the underside of the roof decking. The tanks will need some sort of heat-transferring material that's about an inch thick on their top sides--this is to keep them from getting punched full of nail holes. Use black shingles on the roof to ensure the maximum amount of solar energy is collected. (In normal "green" roofing systems we want them white to reflect solar heat, but in this case we want to grab all the solar heat we possibly can since we're using it. Hence, black shingles.) Then use insulated pipes to transfer hot water from the tanks to your rockbed, where a heat exchanger will unload the heat into the rocks. In the wintertime, you turn off most of the water flow to the roof system--keep a little going just to remove snow from the roof, but too much will drop the rockbed temp.

Advantages: cheap. Technology already exists in proven form for the most part--the anti-nail-hole material needs working on, but other than that...how about using sheets of Hexcel between the roof deck and the tanks? Doesn't make the house look "weird." Will reduce attic temps because you're pulling off most of the roof deck heat to warm up the rockbed. Energy requirements would be fairly low, just enough to drive three or four water pumps.

Disadvantages: wouldn't be easy to retrofit to existing homes because the best place for the rockbed is probably under the basement--especially in a McMansion community where backyards don't exist. Roof would have to be a fairly dark color for best results.

Hmm...how do I get a research grant? Need: small house with southern exposure, truckload of aluminum sheet, vinyl siding hanger's brake, TIG welder, backhoe, dump truck...

Congratulations you've gone back in time to the 70s. There are a lot of approaches to solar, none of them invalidate the value of scalable, efficient energy storage that can be used anywhere.

Your post does not address the post it replied to:
For one thing, the timing for large scale rollout of this technology is not here yet. We need to focus on deploying renewable generation and improving energy efficiency, and government policy is largely reflective of that. As the penetration of wind and then solar increases and the carbon costs escalate to the point where they have a more substantial effect on the existing natural gas generation facilities, there will be larger and larger call for dispatchable solutions that allow the capture of spilled energy from renewable facilities.

That will depend on two things, the price they set for carbon and the natural market economics that work on renewables.

It is, however, a very good technology to watch. I say technology instead of company because as noted, this company's stroke of insight was to match an existing technology to a new application. Lots of people are looking at a lot of different iterations of proven technologies to see if they can find a new market for old ideas and this is one. Another is the use of home heating systems as a means of energy storage. The idea for that is that if a large number of homes use some form of electric heat powered by remnewables and if the heating system stores energy like the rocks, then you can "top them off" during periods of high production and use that as a buffer for the system demand during cold weather.
What that means is that there are probably going to be a lot of competitors coming out with similar systems long before demand is strong enough to pick the market winners.

But the idea is kick ass.

You want to take renewable electricity, turn it into heat, store the heat in rockbeds then use the heat for homes.

It might be more efficient just to go to the industrial customers who aren't running 24/7 operations and offer them incentive$ to run their factories at night instead of during the day.

They built a "proof of ignorance" demonstration project that's probably the size of a Volkswagen Bug, and they've extrapolated the numbers to the point where people like you believe this is the Second Coming. Let's see here...according to them the Isentropic Energy Converter has "99 percent isentropic efficiency." Isentropic means "constant entropy"--according to the University of Oklahoma's website (the first link I found), a process that is both reversible and adiabatic is an isentropic process. An adiabatic process is one which neither loses nor gains heat. I mentioned the perpetual motion machine in my first post on this thread. That's effectively what they're talking about building.

Obviously, then, no process can actually be isentropic because no process can be adiabatic. Since there is no way to actually build a device that will give you the efficiencies they're claiming--the whole thing revolves around adiabaticity, which is a practical impossibility--I would rate Isentropic's claims as "total bullshit."

Were I a gambling man I would bet 99 percent of the world's "electricity storage" is in the form of pumped hydro because it's cheap and it works.

Bloom Box Energy

You'll generate your own electricity with the box and it'll be wireless. The idea is to one day replace the big power plants and transmission line grid, the way the laptop moved in on the desktop and cell phones supplanted landlines.

Large corporations have been testing a new device that can generate power on the spot, without being connected to the electric grid. Will we have one in every home someday? Lesley Stahl reports.

Story here:

http://www.cbsnews.com/stories/2010/02/18/60minutes/main6221135.shtml

They may be 'wireless', but they will need a pipe, or a tank of methane or similar fuel that you refill regularly.

and power plants. Still a very promising technology. It's up and working at Google and EBay corporate sites with little or no problems.

And it is much cleaner than coal.

Yeah, NA natural gas consumption per year, about 28 trillion cubic feet; NA natural gas reserves, 283 trillion cubic feet. http://www.eia.doe.gov/oiaf/ieo/nat_gas.html

Yes, any reliance on natural gas for the long term means importing it from outside North America. I think if the Bloom Energy stuff takes off, it'll be based on biogas or similar.

From near the bottom - "The largest increases in reported natural gas reserves in 2009 were for Iran and the United States. Iran added an estimated 43 trillion cubic feet (a 5-percent increase over 2008 proved reserves) and the United States added 27 trillion cubic feet (a 13-percent increase). ... Much of the increase in U.S. natural gas reserves results from expanded knowledge and exploration of shale resources."

What is the difference? If I have a gallon of gasoline I have X amount of energy stored in a container. If I have a charged lithium battery pack I have X amount of energy stored in a container.

If I need to use this energy for something I have to convert it to power. An internal combustion engine converts the solar energy stored chemically in the gasoline to heat and mechanical energy. The heat is largely wasted and losses to heat accounts for 70-88% ff the gasoline's energy.

If I use fuel cell, I have to run the gasoline (or natural gas etc) through a "reformer" and change the nature of the stored energy from one chemistry to a different chemistry. This results in lost energy, but now I can use a fuel cell to process the chemical energy into electricity and heat. Total losses for process in the fuel cells now on the market are around 60-80% of the energy contained in the gasoline. For the Bloom box the loss is stated to be 52%.

Another term to be familiar with is "energy carrier". That describes the portability characteristic that is associated with liquid fuels, but you should remember that liquid fuels are really stored energy. While the portability factor is the one most people focus on for gasoline, it's important to bear the fact that it is stored energy in mind because when we seek an alternative to gasoline, we are dealing with both the storage issue and with the portability issue. I can store a lot of energy cheaply in a pumped hydro system, but I can't carry that around in my car.

So the application is very important when evaluating these technologies. In the case of fuel cells, the efficiency of the fuel cell with a reformer is better than an internal combustion engine, but it still emits a lot of CO2. We can get the portability but we are using stored energy in fossil fuels and that means CO2.

An alternative is to operate a separate process that uses electricity (from fossil, renewables, or nuclear) to produce pure hydrogen. Of course, that incurs an energy loss from whatever energy state we begin with. The H2 then must be made portable. That incurs another loss. When pure H2 is used in a fuel cell, the conversion efficiency is about 50-60%, meaning we lose 40-50% as heat. But when we look at the process of getting the H2 to the fuel cell.

The alternative for automobiles (where portability is important) is the use of lithium batteries. When we track the same route for energy made portable by storage in lithium batteries as we do for fuel cells, this is what we find. Starting with 100kwh of electricity, for the two methods of making H2 portable for the fuel cell we end up with between 19-23kwh pushing the vehicle down the road; starting with the same 100 KWH for batteries we end up with 69kwh pushing the vehicle down the road - it is simply no contest.



From "Why a Hydrogen Economy Doesn't Make Sense" at http://www.physorg.com/news85074285.html

This chart is 4 years old, so there are some improvements on both sides of the chart, but there is nothing that has been developed that alters the basic relationship that strongly favors batteries.

If we look for applications outside the transportation sector, we need to ask how relevant the portability factor is. If we are looking for a system for our home, business or local housing development, what are the characteristics the system must possess to best meet our needs?

I'd argue that the first point is that it should be carbon neutral. If we are not concerned about carbon, the present grid system is pretty darned good at meeting our energy needs for home use. But if we move to carbon free energy what then? The use of nuclear power fits into the present grid system so we can make the transition by building an additional 400-500 nuclear plants in the US and changing nothing else. To use that strategy throughout the world will require about 17,000 nuclear plants.

The vast majority of independent energy policy analysts do not see that as a viable strategy for a number of reasons. There are quite a few plans for making a transition away from fossil fuels and very few from outside of the nuclear industry advocate for expansion of our nuclear fleet. The particulars of that argument are not relevant for this discussion about applications for energy storage and recovery within a distributed grid system, which would be built around renewables. If we go with the nuclear option, the use of fuel cells from any maker have little value.

So (presuming you are interested in a transition to renewables) what about using fuel cells to meet needs at the home, business or local housing development level?

At the home level the chance seems fairly low since the same efficiency issue with input is at play. In our chart above, we find the answer at the level above the end use level for we want to compare the output of the device delivering the electricty, not what the final efficiency through our refrigerator might be, right? The chart gives us an efficiency range of 21-26% for the fuel cell and 77% for the lithium batteries.

If we go to larger scale systems we are looking at the same issue, only the battery is different. For transportation lithium is best because it sores a lot of energy by weight and volume compared to other types of batteries. But for these stationary applications in the microgeneration range, there are other batteries that are very functional.

What about biofuels? They also have to go through a reformer for the fuel cell and when they do, the fuel cell compares poorly to combined cycle gas turbines in the area of efficiency.

The bottom line is that with a fuel cell because you have to go from electricity, to chemical and back to electricity, the system efficiency is too low. If we look at using the fuel cell with hydrocarbons, then it must go through the reformer, and that is even worse than if we manufacture H2.

If we use of manufactured H2 from renewable sources we have essentially no carbon carbon emissions. But there is still the low efficiency rating. We can use the same no carbon renewable sources with batteries of all sorts much more efficiently.

That's why the low cost, scalable rock battery at 72-80% round trip efficiency that can be used anywhere is a breakthough and why a new iteration of an old design of the fuel cell isn't.

What is the difference? If I have a gallon of gasoline I have X amount of energy stored in a container. If I have a charged lithium battery pack I have X amount of energy stored in a container.

If I need to use this energy for something I have to convert it to power. An internal combustion engine converts the solar energy stored chemically in the gasoline to heat and mechanical energy. The heat is largely wasted and losses to heat accounts for 70-88% ff the gasoline's energy.

If I use fuel cell, I have to run the gasoline (or natural gas etc) through a "reformer" and change the nature of the stored energy from one chemistry to a different chemistry. This results in lost energy, but now I can use a fuel cell to process the chemical energy into electricity and heat. Total losses for process in the fuel cells now on the market are around 60-80% of the energy contained in the gasoline. For the Bloom box the loss is stated to be 52%.

Another term to be familiar with is "energy carrier". That describes the portability characteristic that is associated with liquid fuels, but you should remember that liquid fuels are really stored energy. While the portability factor is the one most people focus on for gasoline, it's important to bear the fact that it is stored energy in mind because when we seek an alternative to gasoline, we are dealing with both the storage issue and with the portability issue. I can store a lot of energy cheaply in a pumped hydro system, but I can't carry that around in my car.

So the application is very important when evaluating these technologies. In the case of fuel cells, the efficiency of the fuel cell with a reformer is better than an internal combustion engine, but it still emits a lot of CO2. We can get the portability but we are using stored energy in fossil fuels and that means CO2.

An alternative is to operate a separate process that uses electricity (from fossil, renewables, or nuclear) to produce pure hydrogen. Of course, that incurs an energy loss from whatever energy state we begin with. The H2 then must be made portable. That incurs another loss. When pure H2 is used in a fuel cell, the conversion efficiency is about 50-60%, meaning we lose 40-50% as heat. But when we look at the process of getting the H2 to the fuel cell.

The alternative for automobiles (where portability is important) is the use of lithium batteries. When we track the same route for energy made portable by storage in lithium batteries as we do for fuel cells, this is what we find. Starting with 100kwh of electricity, for the two methods of making H2 portable for the fuel cell we end up with between 19-23kwh pushing the vehicle down the road; starting with the same 100 KWH for batteries we end up with 69kwh pushing the vehicle down the road - it is simply no contest.



From "Why a Hydrogen Economy Doesn't Make Sense" at http://www.physorg.com/news85074285.html

This chart is 4 years old, so there are some improvements on both sides of the chart, but there is nothing that has been developed that alters the basic relationship that strongly favors batteries.

If we look for applications outside the transportation sector, we need to ask how relevant the portability factor is. If we are looking for a system for our home, business or local housing development, what are the characteristics the system must possess to best meet our needs?

I'd argue that the first point is that it should be carbon neutral. If we are not concerned about carbon, the present grid system is pretty darned good at meeting our energy needs for home use. But if we move to carbon free energy what then? The use of nuclear power fits into the present grid system so we can make the transition by building an additional 400-500 nuclear plants in the US and changing nothing else. To use that strategy throughout the world will require about 17,000 nuclear plants.

The vast majority of independent energy policy analysts do not see that as a viable strategy for a number of reasons. There are quite a few plans for making a transition away from fossil fuels and very few from outside of the nuclear industry advocate for expansion of our nuclear fleet. The particulars of that argument are not relevant for this discussion about applications for energy storage and recovery within a distributed grid system, which would be built around renewables. If we go with the nuclear option, the use of fuel cells from any maker have little value.

So (presuming you are interested in a transition to renewables) what about using fuel cells to meet needs at the home, business or local housing development level?

At the home level the chance seems fairly low since the same efficiency issue with input is at play. In our chart above, we find the answer at the level above the end use level for we want to compare the output of the device delivering the electricty, not what the final efficiency through our refrigerator might be, right? The chart gives us an efficiency range of 21-26% for the fuel cell and 77% for the lithium batteries.

If we go to larger scale systems we are looking at the same issue, only the battery is different. For transportation lithium is best because it stores a lot of energy by weight and volume compared to other types of batteries. But for these stationary applications in the microgeneration range, there are other batteries that are very functional.

What about biofuels? They also have to go through a reformer for the fuel cell and when they do, the fuel cell compares poorly to combined cycle gas turbines in the area of efficiency.

The bottom line is that with a fuel cell because you have to go from electricity, to chemical and back to electricity, the system efficiency is too low. If we look at using the fuel cell with hydrocarbons, then it must go through the reformer, and that is even worse than if we manufacture H2.

If we use of manufactured H2 from renewable sources we have essentially no carbon carbon emissions. But there is still the low efficiency rating. We can use the same no carbon renewable sources with batteries of all sorts much more efficiently.

That's why the low cost, scalable rock battery at 72-80% round trip efficiency that can be used anywhere is a breakthough and why a new iteration of an old design of the fuel cell isn't.