Pro­fessor of materials/​physics chem­istry discusses Tesla's Powerwall for home energy storage

May 28, 2015 by Greg St. Martin

Last month Tesla CEO Elon Musk unveiled a grand plan for home energy storage, and preorders for the system have already sold out until mid-2016. The Powerwall home battery unit comes in two options: a 7 kWh version designed for daily use at $3,000 and a 10 kWh version designed as a backup supply for $3,500, plus installation. It would charge using electricity generated from solar panels—or when energy rates are low—and would also serve as an alternative to using the utility grid and as a backup in case of a power outage. Powerwall's lithium-ion battery is geared toward homeowners and is based on the technology used in Tesla vehicles.

Sanjeev Mukerjee is a professor of materials/physics chemistry and director of the Northeastern University Center for Renewable Energy Technology, where he and his team pursue a range of innovative energy research projects in areas such as , transportation, and alternative fuels. Here, Mukerjee weighs in on the Powerwall announcement and the greatest challenges in energy storage currently facing researchers and industry.

What was your initial reaction to the Powerwall announcement?

Having a bank of batteries at home is not a new idea. Anyone can buy 12-volt batteries and combine them to provide a backup storage solution at home. But where Elon Musk comes in, and where he's been very smart, is looking at scalability. The lithium batteries used in Tesla cars have a high degree of tolerance, or reliability. As I mentioned, a hobbyist can put a home battery like this together, but most people in this country aren't hobbyists. They just want to know if they can go out and buy a ready-made solution.

The Powerwall home battery also appears to include software and switching solutions that allow for integrating it with a solar panel. All of this will be packaged together, which will make it much easier for the average person to adopt.

Musk has also proposed building a mega lithium-battery manufacturing facility here in the United States. The main countries that currently make these batteries are China, Japan, and South Korea, and this would represent a disruption to those countries' monopoly in the market.

Do you envision Powerwall having a major societal impact on the home storage and renewable energy landscape?

The price of solar panels has been dropping steadily. Right now are below $1 per watt, or $1,000 per kilowatt. That's pretty amazing considering a few years ago they were $5,000 per kilowatt. This solar technology is approaching an age in which an average homeowner can get payback on a solar panel for an average home in three or four years.

However, the biggest impact would be primarily in the southern parts of the country in cities such as Los Angeles or Santa Fe, New Mexico. What is preventing adoption right now is that solar can power things in the daytime, but not at night during peak demand when people are coming home and turning things on. That's when you don't have power coming in, so you need to store it someplace. If you can imagine having about eight hours of decent solar radiation available during the day you'd produce about 80 kilowatt hours of energy and using the 10 kWh unit, you'd be able to use part of this energy in a stored fashion. So essentially you're producing eight times more energy than you can store in one of these home battery units. It's still a very expensive solution. It will help mitigate the costs in some places, but it is not for everybody.

I think this is a very good first foray, and they will likely sell a lot of these units. But it's not the ultimate solution either. An important next step for wider dissemination will be to bring down the cost.

What are the greatest challenges in energy storage currently facing researchers and the industry?

I'd put this in two categories: small-scale storage in cell phones and other small devices, and storage at the home and community level. For the latter, these solutions are resigned to bringing down costs. Lithium batteries will be difficult to scale to that cost structure. There are other battery options but there are some technical hurdles to getting them to work as viable solutions. Some examples are metal air batteries and hydrogen bromine batteries. Our research group is exploring and making strides in both of these areas. We've also just filed a patent on the side as well, developing a new material that maintains a battery's high rate capability, which refers to how much capacity you retain when you draw a battery down faster than normal. These types of batteries are typical for power tools like drills and saws and cordless vacuum cleaners that demand a high degree of torque, which draws down the battery very fast.

Explore further: The winners and losers in Tesla's battery plan for the home

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gkam
2 / 5 (4) May 28, 2015
I do not see the Tesla battery for home use. I see it for peak shaving in commercial and industrial facilities.
TheGhostofOtto1923
2 / 5 (4) May 28, 2015
I do not see the Tesla battery for home use. I see it for peak shaving in commercial and industrial facilities.
We know you dont see very well. Dont we?

"preorders for the system have already sold out until mid-2016"

-What a sick little man you are.
gkam
2 / 5 (4) May 28, 2015
And you have their customer list? Those of you who do not understand how electricity works are a real kick. Not having had to pay Large Commercial or Industrial Demand Charges in peak periods, this otto-goober insults those of us who have.
gkam
2 / 5 (4) May 28, 2015
Anybody here understand ratchet clauses, peak, sliding intervals, and how long you pay for one tough 15 minutes, . . so you can teach otto?

Apparently he has never paid a real power bill except for mommy's.
Eikka
5 / 5 (1) May 29, 2015
Not having had to pay Large Commercial or Industrial Demand Charges in peak periods


Again: Most of the energy-intensive industry isn't subject to demand charges because they negotiate their power supply via long-term contracts outside of the market whenever possible.

Even in California, the industry doesn't -have- to buy power off the market anymore, although they may choose to if the power is cheap.

The Enron-manufactured energy crisis in California lead to the deregulation of the energy market where 20 GW of producing capacity were sold from the public utilities to independent operators and then utilities were forced to buy the power back at market price, and no long term contracts allowed. This had the opposite effect from intended and operators started shutting down powerplants to pump up the prices, and the state had to resume long-term contracts to keep the prices down.
antialias_physorg
5 / 5 (1) May 29, 2015
I do not see the Tesla battery for home use. I see it for peak shaving in commercial and industrial facilities.

I could see them in conjunction with an electric vehicle. The power draw of chargers is so high that in some cases the electric infrastructure in a home can't handle it (or it takes a very long time).
But you can charge on of these units up during the day - when you're not home - and then dump the energy into your car straight away.

Most of the energy-intensive industry isn't subject to demand charges because they negotiate their power supply via long-term contracts outside of the market whenever possible.

Many of them have their own powerplants - as it is far cheaper to produce the energy yourself than buy it from the grid at those orders of magnitude.
Other large companies are just tax-exempt which makes the power they buy dirt cheap.
Eikka
5 / 5 (1) May 29, 2015
Anybody here understand ratchet clauses, peak, sliding intervals, and how long you pay for one tough 15 minutes, . . so you can teach otto?

Apparently he has never paid a real power bill except for mommy's.


Enron pulled all sorts of tricks like overscheduling transmission capacity without actually using it, to make it seem like the grid was congested and up to capacity, and then routing power out of state and back in to be allowed to charge more for it. The resulting power prices weren't "real" in any sense. They were entirely artifical.

As a response, the state "deregulated" the market to induce competition, and put it to law that utilities HAD to buy power at spot market price, which lead to the situation where power producers started to shut down capacity intentionally.

As a response to that, the state then took control back from the independents to the utilities through long term power contracts, and the rolling blackouts stopped.
Eikka
5 / 5 (2) May 29, 2015
I could see them in conjunction with an electric vehicle.


I see it as just more extra cost and loss of efficiency. The throughput efficiency of the battery charger and output inverters are on the same order as the car itself, which is around 85% so you now got twice the charging losses AND several times the electricity price.

If before your electric car was marginally more ecological than driving on gasoline, with the extra battery is certainly isn't anymore, and you're only getting about 20 miles out of the pack anyhow.

That's like having a gasoline pump that only gives you 2 liters of fuel. Who would want one?

Eikka
5 / 5 (1) May 29, 2015
Many of them have their own powerplants - as it is far cheaper to produce the energy yourself than buy it from the grid at those orders of magnitude.


Ironically, this is getting more and more common in ever smaller businesses in places where renewable energy is widely utilized. Companies are insulating themselves from the highly variable power prices simply by buying the cheapest power available: natural gas.

The overall effect is that as the portion of renewable power on the grid rises, the demand moves off the electric grid and onto the gas grid.
Eikka
5 / 5 (1) May 29, 2015
See for example:

http://www.wsj.co...34033460

March 2, 2014
Every sixth company in Europe's largest economy now generates its own electricity, roughly 50% more than one year ago, according to Germany's Chamber of Commerce and Industry.

The reason? Ever-higher electricity prices—driven in part by a 22% government-mandated levy to fund renewable-energy sources—are prompting companies large and small to invest in their own power-generation infrastructure.


Of course they get subsidized as well for building solar/wind power, but they largely don't use that power themselves, rather relying on gas and burning process waste. The renewable energy is more profitably sold on to the grid to collect the subsidies.

gkam
1 / 5 (3) May 29, 2015

Eikka, do you work for a coal company? Do you think you are telling us something we do not already know about the problems with alternative fuel development? ? Many of us have been working with marginal technologies for decades now, getting them ready for prime time.

Your carping on the sidelines will do nothing to stop them.
antialias_physorg
5 / 5 (1) May 29, 2015
which is around 85% so you now got twice the charging losses AND several times the electricity price.

Sight..this has been explained to you 100 times. Energy that you just dump is 100% loss (e.g. energy your solar panel captures but you can't use because you aren't home).
Energy that you can store and use (at whatever loss fraction) is less than 100% loss. So you win whatever the conversion efficiency.

Then there's the time factor. Some /among them you) have been harping about that it takes a long time to charge an EC. If you have a DC-DC charger that time is a lot less.

It's just one of these technologies that can make a home autonomous. I can see no drawback in striving for that. It's not like it's a moral imperative to keep paying energy bills and dumping waste into the atmosphere, is there? Listening to you I sometimes wonder whether you think there is.
gkam
1 / 5 (3) May 29, 2015
We do not "dump" energy. If not needed, it is not produced. Excited generators are not run without loads.

I think that idea of "dumping" came from Eikka.
TheGhostofOtto1923
1 / 5 (3) May 29, 2015
And you have their customer list?
Ahaahaaa so youre saying theyre lying because your opinion doesnt coincide with reality. This IS how your world works isnt it?

What a sick little man you are.
Those of you who do not understand how electricity works are a real kick
Well apparently neither do you because you concluded based on your pedigree that
I do not see the Tesla battery for home use
-even though

"preorders for the system have already sold out until mid-2016"

-gkam thinks that being a validation form filler-outer gives him insight that elon musk doesnt have.

What a SICK little man you are.
TheGhostofOtto1923
1 / 5 (3) May 29, 2015
Your carping on the sidelines will do nothing to stop them
Gkam the 70yo wetbrain, who hasnt worked for a decade, thinks he is more insider than elon musk.

How sick.
gkam
2.3 / 5 (3) May 29, 2015
Having been Plant Engineer in several industries, I have more experience in the field of power than the anonymous otto who thinks all engineers do the same thing.

otto has not proven all those units sold were for home use, nor that the primary market for them will not be in commercial and industrial environments, which get hit hard by time-of-use rates with punishing demand charges in some cases.

Did otto look up ratchet clauses, floating intervals, and how long they affect your bill? Would he understand it, . . . it being in the Real World, and not his?
TheGhostofOtto1923
1 / 5 (3) May 29, 2015
Having been Plant Engineer in several industries, I have more experience in the field of power
-than elon musk yeah I know. But he has already sold out of his home batteries while your very excellent knowledge and experience as
Plant Engineer in several industries
-has led you to opine that
I do not see the Tesla battery for home use
...How come?
otto has not proven all those units sold were for home use
Theyre different products.

"Tesla CEO, Elon Musk, announced that the interest in the Powerwall batteries has been "crazy off the hook". With 38,000 orders have been placed so far, Musk predicts this will dominate Gigafactory's (the battery's manufacturer) output until mid-2016."

"2,800 companies are also reported to be interested in the commercial-ready batteries, with the average business placing 10 orders each. Musk estimates that the commercial units will provide 5-10 more megawatt hours than the home units."
TheGhostofOtto1923
1 / 5 (3) May 29, 2015
Did otto look up ratchet clauses, floating intervals, and how long they affect your bill?
You fucking moron. Do you really think that throwing around technical terms will make you any less WRONG?

It only makes you look like that much more of an idiot.

Gkam requires proof but is unwilling to provide proof for his very excellent bullshit because his pedigree is all the proof anyone needs.

Your knowledge and experience are worthless because they make you think you know more than elon musk. It only takes 2 minutes to prove how worthless it is. Day after day after day.

Theres your proof you sick little man.
gkam
3 / 5 (2) May 29, 2015
Thank you, otto. Without your challenges I would have not had the opportunity to tell what I got to do in life.

Sorry about yours.
TheGhostofOtto1923
1 / 5 (3) May 30, 2015
Thank you, otto. Without your challenges I would have not had the opportunity to tell what I got to do in life.

Sorry about yours.
Yeah we know that the only reason you are here is to brag about your alleged and imagined accomplishments, not realizing that the site is full of people who have accomplished and experienced much more than you.

None of us has expressed the slightest interest in your CV have they? Why do you think that is, George? Why is it that nobody cares in the slightest about your past?

Most people are here to discuss science and facts. You post your made-up facts as a prelude into talking about yourself. See the difference?

Why is it you are so buddy buddy with VA psychiatrists? Is it because you are an outpatient?

Are your compulsions and delusions the result of possible VA meds? Or are those meds meant to treat those conditions?

Because if they are, they're not working. You still believe you know more about batteries than elon musk.
gkam
3 / 5 (2) May 30, 2015
How do we get rid of otto and his pathetic need for destruction? He is an admitted anonymous lurker, playing what he calls "games" with the rest of us.

He is convenient at times, since his pathetic challenges allow me to educate him in many fields.

Yes, I see the VA for PTS, having served my nation and been exposed to life-altering experiences while otto cowered at home. Those of us who served have nothing but scorn for his type. Go ahead, otto, make fun of war vets, it's a fun game! All the cowards play it.
TheGhostofOtto1923
1 / 5 (2) May 31, 2015
Go ahead, otto, make fun of war vets, it's a fun game!
Only the lying delusional ones who think they can make up all sorts of bullshit because of their highly dubious pedigree.

So what is PTS? More bullshit? I don't think it's on the list.
http://en.m.wikip...wiki/PTS

-If you mean PTSD then you would have been treated for most of your life including your glory days as a phoney engineer and a spook.

That's a mountain of meds. Perhaps we have at last an explanation for your delusions of grandeur, your compulsion to lie, and your refusal to take responsibility for it.

Reread what I've written here and above. You're a self-centered delusional psychotic who insists that the world is just waiting to hear about your glorious life.

Even though nobody has ever asked you for details or even commented on it.

Any idea why that is? You think maybe nobody gives a shit?

Stay here and continue to be abused for the garbage you post. Or leave.

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