Navigant Research Blog

A Possible Energy Storage Breakthrough

— May 21, 2013

In a recently published paper, Stanford professor Yi Cui revealed a new battery design that could, if it proves durable and effective in the real world, be a significant new technology in the energy storage market.  Like many experimental battery designs, Cui’s battery uses forms of lithium and sulfur.  However, the professor’s battery uses them in a completely novel fashion, sidestepping some of the problems that normally plague lithium sulfur batteries.

To understand why this battery holds so much promise, it’s important to understand the electrochemistry of sulfur.  When sulfur is used in a battery, it sometimes produces polysulfides, which can damage the inner workings of the battery.  When polysulfides collect within the electrolyte of the battery, they cause the other parts to degrade quickly.  That’s why traditional lithium sulfur batteries have such a low cycle life, sometimes lasting only a few dozen cycles.

Cui’s design turns the production of polysulfides on its head: the electrolyte is composed of a lithium polysulfide material.  When the battery is discharging, lithium ions leave a lithium cathode and bond with the lithium polysulfide electrolyte.  When it’s charging, the ions head back to the lithium metal cathode.  The result is a flow battery that, unlike any other flow battery, needs no ion-selective membrane.  Instead, a cheap passive coating of the lithium metal allows the correct ions to pass without leading to degradation of the cathode.

Multiple Breakthroughs

The Cui lab at Stanford will be familiar to readers who have read about previous battery work done there.  He seems to have an uncanny ability to turn out several new battery chemistry breakthroughs every year, ranging from yolk-shaped encapsulants to silicon nano-rods to dye-based batteries.  It seems inevitable that an innovation from the Cui lab will eventually rewrite the energy storage history books.

There’s reason to be hopeful for this particular concept.  This battery has two features that resonate with anyone who has tried to understand why flow batteries haven’t succeeded so far: the materials involved (lithium and sulfur) are relatively cheap and the absence of a membrane eliminates another large cost factor for most flow battery designs.  If the Cui battery can be scaled up from its small laboratory prototype and can withstand thousands of cycles, this concept could lead to a much cheaper form of energy storage than currently exists.

That’s a big “if.”  Many other promising experimental battery designs have proved to be too finicky or too expensive to manufacture to become real-world products.  Cui and his graduate student, Guangyuan Zheng, have shown data that their battery can endure 2,000 cycles without any noticeable degradation, which is a good start.  But the real proof of the system’s success will be in a commercially manufactured, scaled-up model.


The Return of Vertical Axis Wind Turbines

— May 21, 2013

Vertical axis wind turbines (VAWTs) appear to be making a comeback after a few dormant decades, but it’s unclear how much legs the somewhat maligned technology will have in the market.  VAWTs are most commonly known in the United States from their days during the 1970s to the early 1990s in California, when Sandia National Laboratories and several private companies worked together to design and deploy a number of 500 kW-600 kW utility-scale VAWTs in California.  The units worked fairly well, even if not as well as expected, for a number of years.  But they ultimately ran into mechanical problems that stifled their commercial viability.  By that time, interest had largely shifted to today’s more common three-bladed horizontal axis wind turbine (HAWT) designs, and the industry has never looked back.

VAWTs do potentially offer advantages over HAWTs, including producing power with less wind so they can be located closer together and closer to the ground for easier maintenance and installation.  There are at least 28 active VAWT manufacturers in the world today, primarily producing less than 10 kW units intended for use in urban and building-integrated settings.  Yet, many companies in this sector, such as Helix Windpower and Windspire, have faced significant financial challenges.  Small wind turbines in general have faced increased scrutiny, as there are many cases of both VAWTs and HAWTs not performing as advertised in the urban environment.  The establishment of the Small Wind Certification Council has been a major step forward for a small wind industry that is looking to regain credibility.  Still, only five small wind turbines are currently certified by the council – all HAWTs.

These challenges did not, however, prevent the largest building-integrated VAWT installation in the United States from coming online in June 2012.  It uses 18 4.5 kW Venger Wind V2 turbines on the roof of the Oklahoma Medical Research Foundation.  The V2 wind turbines are 18.5 feet tall and are designed to start producing electricity at winds of 8.9 mph, well below Oklahoma City’s annual wind speed average, according to Venger Wind.

Packing Them In

Making inroads in the utility-scale market is a challenging task for VAWTs, given the formidable competition from incumbent manufacturers that have a long history of commercial viability and strong technical performance.  There is strong, though relatively limited, potential in the medium wind turbine market segment (100 kW-900 kW range) related to rural areas, islands, community wind, schools, and other distributed wind applications.  No known commercially available VAWT product currently exists in that power range – Italy’s Ropatec offers the largest known VAWT unit at 20 kW.  But a number of universities and companies are taking a closer look at VAWT technology and applications and are seeking to learn from others’ successes and failures.

A Caltech study that analyzed the performance of six VAWTs more tightly packed together found that they produced 21 to 47 watts of power per square meter of land area, compared to just 2 to 3 watts per square meter from a similarly sized HAWT farm.  Shanghai Aeolus Windpower Technology (SAWT) currently offers less than 10 kW VAWTs, but has stated plans to develop 50 kW and 1 MW units.  Sandia National Labs received a $4.1 million grant in June 2012 to reevaluate VAWTs, including their potential for offshore applications – an opportunity that Japanese, Korean, and Chinese researchers and companies are also examining.

Finally, high-profile projects at Adobe and the Lincoln Financial Field (home of the NFL’s Philadelphia Eagles) continue to drive interest in VAWTs.  But only actual performance details over time will determine if the resurgence of VAWT interest is based on concrete technical improvements or hype.


NIST Inches Toward Cybersecurity Framework

— May 20, 2013

Executive Order 13636 requires, among other things, the National Institute of Standards and Technology (NIST) to develop a “Baseline Framework to Reduce Cyber Risk to Critical Infrastructure.”  There is a lot of good detail as to what is expected to be in this framework, whose requirements run to a full page.  Recently, NIST hosted its first Cybersecurity Framework Workshop to address those necessities.  This particular workshop resulted from the following specific requirement: “In developing the Cybersecurity Framework, the Director shall engage in an open public review and comment process.”  The director of NIST must deliver a framework within 1 year of the publication of the Executive Order (EO); that is, no later than February 19, 2014.

I’m not sure what a framework workshop is, or how many times the word “work” must appear in a meeting title before people will believe that you plan to accomplish something.  At any rate, over 700 people attended the workshop ‑ quite large to qualify as a workshop.  Living in the DallasFort Worth area, I remember years when the Texas Rangers could barely get 700 people to attend their baseball games (unless Nolan Ryan was pitching).  Besides, here in Texas, anything with 700 members is usually called a herd.

Engaged, Considered

Whatever you call it, this event was important.  Strictly speaking, the 700 workshop attendees were allowed to comment, but the EO only requires the Secretary of Homeland Security to “engage and consider” their advice.  Based upon past experience, the likelihood of their input being ignored is very low.

I may be a bit skeptical here because I’ve watched the North American Electric Reliability Corp. (NERC) labor to adopt seemingly minor clarifications to the CIP Reliability Standards (which it then invalidates).  It has repeatedly been hamstrung by large attendee lists that include sometimes contradictory agendas.  Anyway, quoting the EO, 9 months from now we shall have:

  • A prioritized, flexible, repeatable, performance-based, and cost-effective approach, including information security measures and controls, to help owners and operators of critical infrastructure identify, assess, and manage cyber risk
  • Methodologies to identify and mitigate impacts of the Cybersecurity Framework … on business confidentiality, and to protect individual privacy and civil liberties

After that, quoting Section 8(a) of the EO, “The Secretary, in coordination with Sector-Specific Agencies, shall establish a voluntary program to support the adoption of the Cybersecurity Framework by owners and operators of critical infrastructure and any other interested entities.”

In other words, 1 year to develop a framework of non-binding recommendations for the protection of critical infrastructure.  Here in the smart grid world, we already have that.  It’s called the NISTIR 7628 series.  So maybe it’s a very good call to have NIST run this play.  But you’d have to accept that critical infrastructure owners will spend money on protection that they are not required to spend.  To date, that trend is not encouraging.


In the West, Big Coal Makes Its Stand

— May 17, 2013

Overshadowed by the debate over natural gas exports, a battle is brewing in the Western United States over exports of coal to Europe and, especially, to the booming economies of Asia.  Buoyed by rising overseas demand for American coal, big coal producers including Arch Coal and Peabody are seeking to build new ports and new shipping facilities, particularly along the West Coast, to send U.S. coal from the Powder River Basin, in Montana and Wyoming, across the Pacific.

Those plans have met with fierce resistance from local residents and environmental groups.  “I want to make it absolutely clear: I am vehemently opposed for a private, for-profit corporation to use eminent domain to condemn my private land for a rail line to export coal to China,” Clint McRae, a rancher whose family has owned their ranch in the Powder River Basin for 125 years, told a an Army Corps of Engineers hearing in Seattle last December, according to The Los Angeles Times.

Also lining up to oppose the exports are elected officials in Oregon and Washington who don’t wish to see huge coal export facilities built on their coastlines.  Saying that rail links to bring Powder River Basin coal to the West Coast “threaten the health of our communities, the strength of our economies, and the environmental and cultural heritage we share,” Seattle mayor Mick McGinn announced last month the formation of the Leadership Alliance Against Coal, which includes Native American tribal groups as well as politicians from towns in Washington State.

Black Piles

Behind the export push are the remaining Big Coal companies, particularly Arch Coal and Peabody, who have largely abandoned their mines in Appalachia and have seen their share prices drop by as much as two-thirds over the last 2 years as utilities across the United States have moved to burn low-cost natural gas rather than coal.  Peabody actually projects that U.S. coal consumption for power generation will rise in 2013, by 60 million to 80 million tons. Even as coal consumption drops in the United States over the long run, though, demand continues to climb in China, India, and even European countries like Germany, which is phasing out its fleet of nuclear power plants.

U.S. coal exports set a record last year of more than 124 million tons, topping the previous record set in 1981.  Because of “must-take” contracts signed years ago, some utilities in 2012 literally found themselves with piles of coal they didn’t want, and dumped these supplies of “distressed coal” on the international market. As a result, exports of coal are expected to drop this year, while remaining high.

Of six proposed coal export facilities on the West Coast, three have already been defeated. The battle over the remaining facilities could be Big Coal’s last stand in the United States.

Still, as I’ve written here before, the end of coal is likely to be prolonged.  The Economist Intelligence Unit, in a report released this month, said that increased overseas demand for the “surprisingly dynamic commodity will drive world coal consumption to more than 8.4 billion tons in 2015.  By far most of that growth will come from China – which puts the United States in the uncomfortable position of cutting its own use of the world’s dirtiest fuel, while feeding the coal hunger of less-developed economies.


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