Energy storage remains one of the missing pieces of a widespread renewable energy future.

Despite Amory Lovins' arguable claim that renewables in tandem with energy efficiency can serve as effective baseload power, we absolutely need a larger role for energy storage to make renewables effective.  And, Mr. Lovins, please note, for the foreseeable future -- we still need fossil fuels and nuclear power.  

Many Storage Technologies, Many Applications

Utility-scale energy storage in the field today is limited to pumped hydro, a few large deployments using compressed air energy storage (CAES), hundreds of megawatts of sodium sulphur (NaS) batteries, mostly in Japan, and some experiments with banks of lithium-ion batteries, nickel-cadmium batteries and regenerative fuel cells (flow batteries).

Improvements in batteries, fuel cells, hydrogen storage, ultracapacitors, flywheels, phase-change materials, SMES, etc., will come from incremental advances in materials science.  Although a black swan would be most welcome in this field, we are dealing with the limits of known elements, compounds and physics.  Maybe some revolutionary advance will rock our paradigms, but for now, improvements in energy storage will come from hard, slow work in the labs of materials scientists.

A few firms are looking into energy storage via ammonia synthesis.  The concept is to use energy generated by remote or offshore wind turbines to perform "solid-state ammonia synthesis" and transport that ammonia by land or sea to be used as a fuel.  This obviates the need for distant wind farms to be expensively connected to the grid. 

Doty Energy wants to use off-peak wind energy to efficiently synthesize fuels, like gasoline and diesel, from CO2 and water.  According to the company founder, David Doty, strong arguments for the concept include: (1) the energy storage density in stable liquid fuels is two orders of magnitude greater than the energy storage density in batteries, (2) the energy stored in liquid fuels can then be used seamlessly within our current transportation infrastructure, and (3) the chemical processes being developed promise the scalability needed to competitively replace petroleum-based fuels.  Doty's process electrolyzes water and combines the generated hydrogen with CO in a Fischer-Tropsch process to produce the liquid fuels.

Amongst the many energy storage technologies we've covered:

Gravel-based thermal storage from Isentropic Energy -- Thermal Energy Storage Breakthrough?

Compressed Air Energy Storage (CAES) part 1, part 2, part 3  

Ice -- Ice-based thermal storage, also from Cryogel

Ultracapacitors -- Maxwell and the Promise of Ultracapacitors

And since there are a variety of flavors of utility-scale storage applications -- frequency control, load levelling, peak shaving, spinning reserve, etc. -- different applications will call for different technologies. Grid storage could be an $8 billion market by 2016.

Energy Storage Policy

Technology isn't the only element spurring on energy storage -- policy is an accelerant, as well.  As reported last week, AB 2514, supported by California Assembly representative Nancy Skinner and state Attorney General and gubernatorial candidate Jerry Brown, will require utilities to obtain 2.25% of their peak power from storage systems by 2014 and 5% of their peak power from storage by 2020. 

Here's an article by Rep Jay Inslee, the Democratic Congressional Representative from Washington, on The New Storage Economy.

The Hydrogen Highway is Not Dead.     

Vitalie Stavila of Sandia National Labs presented at a conference last week on the technical progress of using complex metal hydrides for reversible hydrogen storage.

Sandia is leading the Metal Hydride Center of Excellence looking to reach the goals that the DOE has set for hydrogen storage through the development of reversible metal hydrides materials.

Although Steve Chu and the DOE have slowed down hydrogen research in favor of our current energy policy (that's a joke, we don't have an energy policy), hydrogen fuel and storage is alive and well in research labs.  There is still a community of scientists laboring to improve performance and discover materials to enable the hydrogen highway.

Hydrogen has almost three times the energy content of gasoline (120MJ/kg vs. 44MJ/kg), but the low density of H2 gas means low volumetric energy content.  Hydrogen is abundant, but it exists only in the form of compounds.  And volumetric compression and storage remain problematic.

Metal hydrides represent a class of materials with volumetric densities higher than gaseous or liquid hydrogen that could enable effective solid state hydrogen storage.  There is a DOE hydrogen storage program with stated goals, but according to a presentation by Sunita Satyapal of the DOE, "No [hydrogen] technology meets targets."  Here's a link to a long list of DOE publications on hydrogen research.

This remains complex stuff and heady materials science.  Some of the more promising materials being investigated are complex metal hydrides, including metal alanates, amides, borohydrides and their derivatives.  The DOE wants a reversible 5.5% hydrogen storage system and according to Stavila, "As of now, none of the materials investigated so far satisfy all of the DOE targets."

There is also a time factor involved in getting these materials to absorb and release hydrogen.  Despite significant improvements in the storage capacity, most of the hydride materials still require high temperatures to decompose and release their hydrogen.

Michael Kanellos reported on a virus that makes hydrogen and I covered Sun Catalytix, a VC-funded company looking to inexpensively electrolyze water.

Early-stage startup Pilus Energy makes a microbial fuel cell which produces hydrogen gas and DC electricity from the metabolism of organic materials by genetically engineered bacteria.  Feedstocks for the Pilus bioreactor are organic compounds found in waterways, plant pulps, farm wastes and sewage.  A video illustrating this concept is here.

Venture Capitalists Vie For the Winning Energy Storage Technology

At least five utility-scale storage startups have closed on $65 million in venture capital funding so far in 2010.  Here's a list:

  • Prudent Energy raised $22M for Vanadium redox flow batteries.  
  • General Compression's $17M Round A for near-isothermal CAES to enable "dispatchable wind."  
  • Enervault, still in stealth-mode, raised $3.5M for flow batteries  
  • EnerG2 raised $3.5M to develop nanoscale materials for ultracapacitors for EVs, PHEVs, and for hydrogen storage.  Perspective from EnerG2  
  • Isentropic Energy raised $2.3M for gravel-based thermal energy storage  
  • EnStorage raised $15M in a Round B led by Warburg Pincus for flow batteries

It's Not Just Startups Going After Utility-Scale Energy Storage  

GE Energy Storage Technologies recently unveiled a battery technology for utility companies and is claiming that it will make a $160 million investment in this battery technology, developing new materials, new manufacturing technologies and intelligent controls.  GE claims that the battery has the ability to last up to two decades, while providing optimal charge and discharge times in extreme temperature environments. 

GE claims that the battery is suitable for transmission and distribution upgrade deferral, time shifting, congestion relief, peak shaving, load following, and reserve capacity and will support end-user applications such as time-of-use (TOU) management, demand charge reduction, and power quality improvement. 

GE's battery is a sodium halide battery chemistry obtained through an acquisition of Beta R&D in 2007.  The $160 million investment is being made to start up a factory on the GE Energy campus in Schenectady, NY, with first saleable production scheduled for July 2010.  The initial target markets are for telecom and Uninterruptible Power Supply applications.

GE is also an investor in battery maker A123.

The Cost of Lithium-ion Batteries for Utility-Scale Storage

"Lithium ion is getting to megawatt scale," according to Dan Rastler of the Electric Power Research Institute, citing a 1 megawatt-15 minute Li-ion system.  He adds, "There are as many different Li-ion chemistries as there are California wines."  There are currently early field trials by Altair Nano and A123 using Li-ion at utility scale.

According to Rastler, "We need to get below $300 per kilowatt-hour installed, all in," and the cost of Li-ion ranges from $400 per kilowatt-hour to $1,200 per kilowatt-hour.

Haresh Kamath of EPRI's Technology Innovation Group said, "Storage is a great idea -- except for the cost."  Kamath expects the cost of large-format Lithium-ion (for electric vehicles and utility-scale storage) to drop to $250 per kilowatt-hour.

China's BYD is building utility-scale battery based grid storage from their LiFe batteries. They are deploying 4-megawatt energy storage batteries for ancillary services and energy arbitrage. According to a spokesperson, the battery cost was in the $500 per kilowatt-hour range, which is within striking distance of many experts' competitive target of $250 per kilowatt-hour.

Jonathan Howes, the Chief Technical Officer of U.K. start-up Isentropic Energy, claims his large-scale storage costs are an order of magnitude lower than lithium-ion batteries or other stored energy technologies -- $55 per kilowatt-hour currently, with a path to get down to $8 per kilowatt-hour.

And Finally, a Few Words on Ultracapacitors

Market researchers predict that the ultracapacitor (a.k.a. supercapacitor or double-layer capacitor) market will grow rapidly in the coming years, reaching $500 million by 2011 or 2012.  This growth will likely be driven by the automotive and transportation sector, as well as by applications in renewable energy, consumer electronics and industrial power management.  
Compared to lithium-ion batteries, which gradually lose their capability to hold a charge after a few thousand charge/discharge cycles, ultracapacitors can withstand hundreds of thousands of charge/discharge cycles.  What's more, ultracaps work well at temperature extremes that hamper battery performance. 

The quick energy jump from ultracapacitors is suited for peak power applications such as elevators, forklifts, consumer electronics and back-up power applications.  In the longer term, ultracaps might serve as alternatives to battery banks for utility-scale power grid applications -- providing a short-term electricity supply during power outages.

Players in the market for ultracaps are Maxwell, Panasonic, NEC TOKIN, Ioxus, Seiko Instruments, Cooper Bussmann, NESSCAP, Cap-XX, and LS Ultracapacitor.  There are many others vying for this emerging market and lots of R&D by companies big and small.

Of course, if you're discussing ultrcapacitors, the conversation eventually turns to the topic of EEStor, the mysterious ultracapacitor start-up that promises a disruptive leap in performance. 

I asked Maxwell's CEO about EEStor and his comments were diplomatically limited to the following observation:  "I'd be more than happy to compare our data to theirs," but "I haven't seen a prototype."  He added, "My experience with technology is, there are many things that are possible.  The question is -- can you make money, can you make a profit, can you make it work and will anybody buy it?"

Steve Pluvia, a frequent commenter on the GTM comment boards, said, "EEStor is nothing more than a vehicle for a Canadian pump-n-dump, specifically Zenn Motors.  Zenn has a powerful Canadian hype team supported by a crooked bucket shop (Paradigm Capital), paid promoters and degenerate gamblers."   

EEStor has received funding from Kleiner Perkins, although Kleiner may have elected not to participate in their most recent funding round.  Other than that, nothing to report on EEStor except the usual unsubstantiated blog chatter.

Stanford University received $1 million from the ARPA-E program to develop an "all-electron battery," a new class of electrical energy storage devices for electric vehicles. The new battery stores energy by moving electrons rather than ions and uses a novel architecture that has potential for very high energy density.

Penn State University also received $1 million for "a novel energy storage device based on a 3D nanocomposite structure with functional oxides that provide a very high effective capacitance."  

For EEStor, this might represent competition or corroboration or even an IP challenge.

Here's a link to a report on ultracapacitor technology and applications from GTM Research.