Comments on: How ultracapacitors work (and why they fall short)

By: eric

eric — Mon, 28 Nov 2011 22:26:56 +0000

wow! really informative article about how small capacitors get big! http://t.co/pvABLLwS #innovativetechnology

By: guest

guest — Wed, 03 Aug 2011 11:08:45 +0000

Great article. Part of the issue is that the expectation is that Ultracapacitors will and hope to replace batteries. Maybe sometime in the future as technology of UC’s improves that may be possible….EEStor is a prime example of this…but until then, in high energy applications, such as grid, EV’s, etc., UC’s are relegated to be used in conjunction with batteries.

By: Saml

Saml — Fri, 22 Jul 2011 17:34:15 +0000

Josie.well written article. We would all love to get rid of the pesky batteries which pollute and need frequent replacement with something that can be quickly recharged and never replaced. There is always a trade off between desired functions and limits of physics known to ua today. Just as there is a market and usefulness for alkaline cells today there is a market and role for supercaps. The title is poorly chosen.

By: EVsRoll

EVsRoll — Tue, 19 Jul 2011 00:43:16 +0000

Great article. Ultracaps have a future, already used in busses as you point out.

More on the capacitor and the EV here: http://www.evsroll.com/Capacitor_Explanation.html

EVsRock!

By: Saro

Saro — Mon, 18 Jul 2011 23:12:33 +0000

Robert,
There are a couple of papers in the literature that claim double digit energy densities with graphene ultracapacitors, and even one that claims 85 Wh/Kg, which is comparable with Lithium based batteries. To my knowledge there are no commercially available graphene ultracapacitors yet though.

By: robert

robert — Mon, 18 Jul 2011 16:22:26 +0000

I was wondering with graphene being used more in ultracapacitors does this increase their storage capacity or do they still lag greatly behind lithium batteries?

By: Mark Wendman

Mark Wendman — Sat, 16 Jul 2011 16:29:36 +0000

Katie,

You are indeed correct. All present ultracapacitors have a modest fraction of the energy density ( gravimetric or volumetric ) of batteries ( esp LiIon), hence uncompetitive for main method of electrical energy storage, where capacity is at issue, like in EV’s even HEV’s.

By: Saro

Saro — Tue, 12 Jul 2011 18:55:47 +0000

Great article. I am surprised though that there is no mention of transition metal oxides. Cheap metal oxide nano-powders (Magnesium oxide for example) are a very promising way to make ultra-capacitors, even though the physical and chemical nature of how they function is slightly different.

By: Katie Fehrenbacher

Katie Fehrenbacher — Tue, 12 Jul 2011 15:59:23 +0000

@Andrew Galloway, thanks! @Mike Sund, Good points, but also they clearly fall short in certain ways or they would be providing energy storage for a lot more things right now, like new EVs.

By: Mike Sund

Mike Sund — Tue, 12 Jul 2011 15:54:41 +0000

Fall short of what? As the writer correctly points out, ultracapacitors are power devices, capable of charging and discharging rapidly, vs. batteries, which store far more energy but charge and discharge slowly. UCs also operate normally at extreme temperatures, which batteries don’t, and they don’t wear out as batteries do. This makes them ideally suited for many, many power-specific applications, and they can complement batteries in many others, such as in regenerative braking systems, where their rapid charge rate makes them much more efficient at capturing and storing energy during a braking event that lasts a few seconds. How much charge can a battery accept in 10 seconds? Had the author bothered to consult a manufacturer, she would have learned that UC cells and modules can be linked in series to satisfy high voltage applications, such as the 750-volt systems employed in the approximately 4,000 UC-equipped hybrid transit buses now in daily service.