Ultracapacitor -- Battery: Hybrid Electric Power

Combining the high energy density of batteries with the high power density of ultracapacitors, provides a better power profile than either alone. From Australia's CSIRO:

The UltraBattery combines a supercapacitor and a lead acid battery that, according to the CSIRO, creates a hybrid car battery that lasts longer, costs less and is more powerful than current technologies.

"Previous tests show the UltraBattery has a life cycle that is at least four times longer and produces 50 per cent more power than conventional battery systems," Mr Lamb said.

"It's also about 70 per cent cheaper than the batteries currently used in HEVs."

Australian Much more on CSIRO at Brian Wang's Blog

Or from the British Motor Show, a Mini-Coop conversion incorporated battery-ultracap hybrid power:

At the recent British Motor Show, PML Flightlink and its partner Synergy Innovations showed a MINI QED — an in-wheel, plug-in, series hybrid conversion of a MINI, which many would agree is a fun car to drive even before these developers achieved an ability to accelerate from 0-60 in 4.5 seconds.....PML Flightlink put 350V worth of 11 Farad ultra capacitors into its Mini QED prototype. The ultra capacitors accept power from regen braking and discharge when high current is required for acceleration.

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A Chinese hybrid car effort uses batteries with ultracaps:

For Maxwell Technologies and Tianjin Lishen Battery, hybrid describes a new sort of energy storage product that combines ultracapacitors with lithium-ion batteries. The two companies recently announced they would partner up to produce this hybrid power source, and samples should be available early next year, possibly in EVs....David Schramm, Maxwell's president and chief executive officer, said this hybrid tech "will give end-users the best of both worlds in terms of the long cycle life, rapid charge/discharge characteristics and low temperature performance of ultracapacitors and the large energy storage capacity of lithium-ion batteries."

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Secretive Texas startup EESTOR seems to be developing a combination battery/ultracapacitor that is attracting investment from Lockheed Martin, and intense investigation by GMC.

The combining of battery and capacitor attributes is quite exciting. Capacitors are very fast acting allowing very quick charge and discharge abilities that will dramatically improve the usefulness of devices that are self-storage powered. Whether a cell phone, laptop or automobile these attributes will have a strong positive impact in usefulness and consumer adoption.

New Energy

This is the basic idea behind the combination approach:

As a quick energy storage platform, a supercapacitor can charge or discharge in a time of mere microseconds to seconds, whereas batteries take minutes to hours. However, the energy density for batteries is much higher. Hence many believe that the ideal backup energy storage device would be a hybrid of battery and supercapacitor. To be useful in that role, however, supercapacitors must be easily made and integrated onto chips.

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Here is an interesting combination of fuel cell, supercapacitor, and battery (my favoured approach):

A fuel cell system that employs a super capacitor and battery electrically coupled in series with each other and in parallel with a fuel cell stack on a power bus line. As the voltage on the power bus line changes over the operating requirements of the system, the super capacitor is charged and discharged over a relatively large voltage swing, such as an 85% SOC swing. The super capacitor equalizes or voltage matches the voltage variation on the power bus line as set by the stack voltage to the voltage of the battery. Therefore, the battery, while providing the majority of the energy and power during charge and discharge, has a relatively small defined SOC swing, which acts to maintain the battery life.

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Here is a combo hybrid for delivery vans:

Azure Dynamics is perhaps the best example; they have built delivery vans with electric drives that included super capacitors. With the decreasing size of such energy storage, there even has been a “proof-of-concept” car. But, such an approach, sending “regen” from brakes and suspension into the “power-rich”,ultra capacitor module1, which then gets depleted before any additional charge is drawn from the battery module

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These are just a few examples of various attempts to achieve the electrodynamic "sweet spot" that will painlessly replace internal combustion engines with electric drive. We still need some breakthroughs in nano-materials, nano-assembly, and nano power electronics. But it is happening.

Nanotube Supercapacitors--Energy Density vs. Power Density

Stories like this and this are plentiful today around the web. It is exciting to see features of nanotechnology incorporated into energy technology, to aid the transition away from a petroleum economy. The new carbon nanotube-supercapacitors will be a huge leap above what is currently available.

If you look at the graphic above, and the graph to the left, you will notice various energy sources plotted with horizontal axis energy density by vertical axis power density. The power density is how much power the device can supply, and the energy density represents how long the device can supply the power. If you will notice, a supercapacitor is high in the top left corner, representing a high power density, but a low energy density. A supercapacitor can supply a lot of power for a short time.

The fuel cells and battery systems have lower power density, but higher energy density. They can supply lower power but for a longer time. A fuel cell car, for example, might go a long distance if supplied with enough fuel, but it would have difficulty accelerating quickly.

We tend to compare energy delivery systems against the internal combustion engine (ICE), which occupies the upper right hand corner--signifying both high energy density and high power density. An ICE powered automobile can go a long distance, AND accelerate quickly. Any practical substitute for the ICE powered auto would need to do the same.

How can you replace the internal combustion engine's superlative qualities? Obviously, there is no single replacement technology that will do the job. The ultracapacitor gives out too quickly, and the fuel cells lack power boost. But there is a possibility that the combination of nano-supercapacitors with advanced fuel cells, or advanced storage batteries, would come close enough to the performance of an ICE. Using cleaner fuels to generate the capacitor/battery charge, and to provide the fuel for the fuel cell, will help the environment tremendously in comparison with the pollution from an ICE.

If you want more graphs to illustrate the contrasting concepts of energy density and power density, go here. This article has more ideas on using nanotech to improve energy storage. This is a general discussion of ultracapacitors (supercapacitors).

See related Al Fin posts here, and here.

Reminding us that we are only a few breakthroughs away from a true revolution in energy production and distribution, Energy blog returns to the topic of ultracapacitors. The new product discussed appears to blur the boundaries between ultracapacitors and storage batteries. See this posting for more details. Also see this previous Energy Blog posting on supercapacitors.

The hydrogen economy becomes unnecessary if electricity itself can be stored efficiently in a medium that can charge and discharge through an indefinite number of cycles, and store electricity with almost no leakage. If a renewable energy source of electricity charges the automobiles electric storage directly, without intervening hydrogen and fuel cells, the process is more efficient and less unwieldy.

Supercapacitors vs. Batteries: An Electrifying Race

The Energy Blog scores another homerun, with its post on supercapacitors. Supercapacitors are fast. They charge fast and they discharge fast. Think of the supercapacitor as the hare, and the storage battery as the tortoise, and you will get the picture.

The third component of the electrical triumvirate is the fuel cell, which acts as the power generator, slow and sure. Oh, and the properly sized electric motor as an actuator. The combination may be a bit too heavy for a regular commuter automobile, but with advances in all three technologies in the pipeline, it may not be long.

Supercapacitors have many uses besides acting as a power boost and regenerative brake for vehicles. Read the article and follow the links.