Tesla CTO Straubel On Batteries, Energy Storage And Technology

MAY 29 2014 BY MARK KANE 25

Tesla CTO JB Straubel recently was the keynote speaker at the annual energy storage symposium put on by Joint Venture Silicon Valley.

It seems that Straubel sees the answer for the future in leveraging scale:

“We Should All Be Thinking Bigger”

“EVs for the mass market. We weren’t founded to make sports cars; we were founded to drive a revolution. You have to sell millions of cars to move the needle.”

In particular, on the Tesla giga factory, Straubel stated that stationary energy storage could grow faster than automotive batteries:

 “Maybe this whole group is not thinking in large enough scale for the market size of energy storage.”

Current And Former Tesla Vehicles

Current And Former Tesla Vehicles


Straubel noticed that in 1990s, the state-of-the-art EVs had lead-acid batteries, then came lithium-ion batteries, some prototype cars and low-volume production began in 2008 (Tesla Roadster). Now, almost every automaker has or is planning some kind of plug-in vehicle.

There is no single type of lithium-ion battery. We have many types of chemistries, most of which are improving over time. According to Straubel, over 10 years energy density has/will double. Some of this timeframe falls on the 5 years between Roadster and Model S, which has 40% “better performance,” according to Straubel.

Energy density is still improving, but this is not continuous.  Rather, it’s smaller or bigger jumps from time to time.

Stationary energy storage

Tesla's stationary energy storage (credit to Greentech Media)

Tesla’s stationary energy storage (credit to Greentech Media)

Tesla is using the “same architecture” for stationary energy storage systems as it does for its electric vehicles.

The Tesla factory in Fremont in 2013 got a 2 MWh battery pack to reduce peak demand by about 10% and, by fall, this system will be expanded to 4 MWh.

Some smaller system are installed for Supecharging stations and some by SolarCity with solar arrays:

“We’ve started piloting these applications,” said the CTO, pointing out that there is a 400 kilowatt-hour battery pack at the Tejon Ranch supercharger site in Southern California. The “supercharger is the perfect application for energy storage” with its “incredibly peaky load.” he added.

The important hurdle is the business model

“the value of backup power is hard to quantify.”

“how you make a business case to the customer”

But Straubel expects that over the next decade, energy storage will grow because it’s needed to increase the share of renewables on the grid.

*For more on Straubel’s keynote speech, follow this link to Greentech Media’s article.

Tesla's stationary energy storage (credit to Greentech Media)

Tesla’s stationary energy storage (credit to Greentech Media)

Source: Greentech Media

Categories: Tesla


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25 Comments on "Tesla CTO Straubel On Batteries, Energy Storage And Technology"

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A 400kWh pack could power my house for 2 weeks. Nice to have if the power went out.

Nice to have for disconnecting from the grid!

Really? 28.5 kWh a day perhaps you should start thinking about turning off some of those lights 🙂

He has a plugin car which can easily consume half of that energy alone….

My last bill I used 856kWh in 33 days. That’s 26kWh/day. I don’t think that is excessive.

I just looked up the average monthly electricity use per household and it’s 920 kWh. I used less than that in over a month, and I have a plug in vehicle. I think I’ll leave my LED light bulbs on in my house w/out worries.


On my last electric bill 4/21-5/20 I used 416kWh. I use my Volt every day to go to work (20 miles round trip) and plug in (110 outlet) every night.

LED bulbs in every bulb socket a must.


I’m not quite privvy to the exact specs, but our datacenter’s Big UPS is probably about 400 Kwh. Technically, it’s for backup power until we can get the diesel generators on, but by itself it can last about two whole days. Because sometimes your diesel generator doesn’t work exactly as planned. 🙂 It doesn’t hurt to absorb any excess power said generator generates, just like how Prius owners can power their house in an emergency.

Well, now we know more precisely what the gigafactory is for.

5kw and 10 kwH can be just a starting point for residential usage. My need is 11kw use and 30-40 kwH capacity. Perfect fpr my energy+ house. I hope Tesla can scale the residential units. Would be great.

But dont underestimate LG. LG is already in the residential market with SMA. And they deliver car manufacturers as well.

I think Li-ion’s virtue, in higher discharge rates and better cycle life, escapes many who still think lead-acid will be the go-to.

There’s going to be a blizzard of electricity news, as the full complexity of the EPA rules comes out over the next few days. Grid storage won’t be big, but there’s enough to decipher about alternatives, decoupling and conservation measures, to, um, challenge the auto-analyst.

The cycle-life is a big one. Yes, the energy density is not needed for stationary applications but a long cycle life is important.

Ah ha! I thought they were using big battery packs at the superchargers. You kinda have to because otherwise the utilities will charge you huge ‘demand charges’ for drawing at such a high rate. And unless the supercharger is near a HV substation, the local grid might not even be able to handle it.

I’m still not convinced that batteries for solar PV is a large market though. Perhaps if utilities start charging outrageous fees for net-metering.

NOT at the price that Solar City is quoting.

$180/month leasing for those “Tesla Battery” backups for Solar City customers.

PG&E Exempts DCFC from demand charges.

There is only one Supercharger site that uses batteries, Tejon Ranch. As it is, local grids are barely affected by Superchargers. The way that Tesla uses dedicated 480V transformers directly to high voltage distribution makes the incremental current draw very small. Also, the chargers ramp up the current slowly, so you will never see lights dim and other bad things that happen when you have high in-rush currents.

If they reach 100,000watts, or so, that’s all that matters in straight forward demand charges. I don’t think that, apart from storage, there is much that can be done to avoid a high instantaneous draw, like that. I don’t believe transformers store, and may be wrong about what rate schedules this type of electric service adheres to.

I think the issue is cost. Assuming Wikipedia has is about right and 2.5 Wh worth of battery costs about 1$ then the residential 10 kWh unit is about $4,000. Assuming you charge the system overnight and use it during the day and further assuming you can shave off 10c per kWh, that gives you a saving of about 1$ per day. With that you would have to run the system 11 years to break even.

For stationary systems, flywheels on magnetic bearings may be better in the long run, especially if BMW bring the carbon fibers price down these systems are made from.

White Leaf, I think most compare on “kwh” price, where your quote works to $400/kwh. Most are estimating $200-300 for Tesla, these days. Barclays estimated $250/kwh, last week.

Stationary storage is already hitting $160/kWh:

I don’t think Tesla’s batteries will ever be as cheap as those engineered for stationary storage. The latter really doesn’t care about density, and it allows so many cheaper materials to be used.

The real value of the stationary batteries for a lot of utilities is the peak demand reduction during peak summer afternoons – i.e. kW, not kWh. Here in Redding, the local utility figures that one kW of demand reduction is worth about $3,000 if it can last for the entire 4-hour peak from 4 pm to 8 pm. Solar PV doesn’t quite cut it, as output plummets after about 5 pm and takes away revenue. So a 5 kW/20 kWh battery bank (with installation, inverter interface, etc.) would be worth $15K to them. I don’t think the batteries are quite at that price point for complete all-up installations, but they are close. Also, for individual owners, those on time-of-use meters, you could “recharge” your battery bank at night, then discharge it during that afternoon peak. As my calc shows, though, you’d need a 4 kWh/kW energy-to-power ratio, not just two, to really make a difference for peak shaving.

Check out EOS energy. They’re using zinc-air batteries, and claim 10,000 cycle life.

They’re building 4-hour storage for less than $1/W. What’s interesting is that this is on par with peaker plants. So if you can recharge the battery with electricity that’s cheaper than a peaker’s fuel cost, e.g. by skimming a little from a very efficient, steady state CCGT plant (~3c/kWh natural gas usage), you have a wholly cheaper solution.

Exactly! Can the peakers. When wholesale natural gas was well north of a buck a therm a few years ago, peaker plant kWh cost was through the roof. NG will be back in that $ range sooner than most realize and battery and other energy storage/demand-side-management systems will be a hot commodity.

Yeah, and they will be more efficient when located at homes and businesses rather than centralized at utility-scale generation plants.