• Liquid batteries to pour on green energy?

    Liquid batteries that can store excess energy generated by sources such as wind turbines could accelerate adoption of the green technology.

    By John Roach, Contributing Writer, NBC News

    Banks of scorching hot batteries filled with molten metals may be the long-sought silver bullet to make large-scale adoption of wind and solar energy a practical, purely green reality.

    Such a storage solution is needed because, as we know, the wind doesn't always blow and the sun doesn't always shine where and when it's needed.

    "Right now, if you run a solar farm or a wind farm and you want to deliver electricity when the wind isn't blowing or the sun isn’t shining, the cheapest way is to get a gas-fired peaking unit," Donald Sadoway, a materials chemist at the Massachusetts Institute of Technology, told me Monday.

    Gas-fired peaking units are mini power plants that can be turned on and off quickly to meet demand for electricity when other sources are unavailable or maxed out.

    "Those things are cheap to buy, they are cheap to run, and the price of natural gas has been falling recently in the United States. So the way people have been looking at (shoring up) renewables is to turn to natural gas," Sadoway explained.

    "And that's fine. It's not illegal. There's nothing immoral about it," he added, "but it is not 100 percent green at this point."

    For the industry to adopt the greener battery technology, the cost of the battery has to be as cheap, efficient, and reliable as state-of-the art natural gas-fired peaking plants. 

    Sadoway and his colleagues are hard at work on a liquid battery they believe will meet these criteria. On Monday, they described their progress in the Journal of the American Chemical Society.

    Metal cocktail
    The battery is a cocktail of metals that naturally settle into distinct layers because of their different densities, similar to a "black and tan" pint served at British pubs, where dark stout rests on top of denser pale ale.

    Batteries need three layers — positive and negative poles and a membrane between the charges. In the case of the liquid battery, molten metals on the top and bottom serve as the positive and negative poles and a layer of molten salt serves as the membrane.

    "The principle of the battery is an alloying reaction," Sadoway explained. 

    Alloys are metals made via the combination of two or more metallic elements. In the liquid battery, the top layer is magnesium and the bottom layer is antimony.

    "The driving force for current is the desire of magnesium to enter the antimony and form an alloy," Sadoway said. "In order to alloy, the magnesium has to first get across the molten salt and in order to do so, the magnesium has to lose two electrons and become a magnesium ion."

    Those two electrons are what escape to the wires to power our gadgets and appliances. 

    "When the magnesium ions get to the interface with the antimony, they acquire two electrons which have been pulled out of the external circuit and then that makes neutral magnesium which then alloys with the antimony," said Sadoway.

    To charge the battery, the process is reversed. 

    Sadoway and his colleagues have tweaked the recipe of this liquid cocktail for several years and gradually scaled up the size of the batteries. 

    The initial tests consisted of a battery about the size of a shot glass; then they went to a battery the size of a hockey puck and, now, the team reports a six-inch-wide version that has 200 times the storage capacity of the original.

    Keeping them hot
    To keep the metals in a liquid state requires a battery operating temperature of 700 degrees Celsius (1,292 degrees Fahrenheit).

    This heat comes at an energy cost — "we have to lose some of the energy we are storing in order to keep the battery at temperature," Sadoway explained.

    Tests show about 75 percent efficiency — that is, for every 100 units of electricity put in the battery, 75 units come out. The rest is spent keeping the battery hot and lost due to inefficiencies in power electronics and converting back and forth between AC and DC.

    A loss of 25 percent is actually quite reasonable, according to Sadoway. As long as more than a 25 percent spread between the price of electricity when the battery is charged and discharged, a utility can recoup its investment cost and make a buck.

    For example, a utility could charge up its battery in the middle of the night when the wind is blowing and rates are low and then sell it back to the grid in the afternoon when rates are high. 

    "In certain markets like California, there can be day-night price swings that can be not so many percent, but so many X," Sadoway noted. "In a market like that, this thing would do just fine."

    Battery vs battery
    According to Sadoway, who has started a company, Liquid Metal Battery Corp. to scale up and sell these batteries, the liquid approach is potentially better than competing technologies such as lithium ion batteries, which require the expansion and contraction of solid parts in order to work.

    All this swelling and contracting amounts to wear and tear, which is often why the lithium ion batteries in laptops, for example, go kaput after a few years.

    "Those kinds of failure mode are absent in this battery because it is all liquid and liquid can accommodate volume changes," Sadoway noted. 

    Lab tests, he said, show that the lifetime of the battery isn't limited by its capacity to hold a charge so much as by the lifetime of materials used to encase and insulate it.

    Current materials, he said, may begin to corrode after 10 to 15 years sufficiently to change the chemistry of the battery or permit the battery "to eat its way out of the case."

    Another advantage to the liquid technology, he added, is the abundance of the raw materials used to build it. Magnesium and antimony are abundant in the United States and low cost.

    As well, assembly of the battery is straightforward. Due to density differences, for example, the layers self assemble. "No clean rooms, no fancy nano-tech, nothing like that," Sadoway said.

    Daniel Kammen directs the Renewable and Appropriate Energy Laboratory at the University of California at Berkeley. He said the biggest challenge for the liquid battery is the high operating temperature.

    "Even if the waste heat can be harvested for an added benefit, systems operating at over 1,000 degrees are going to be a challenge for long-term maintenance," he told me in an email exchange on Tuesday. 

    Shipping-container-sized battery
    Sadoway's startup up is focused on scaling up the battery technology with the best chemistry that comes out of his lab at MIT. While the lab has reached a six-inch diameter cell, the company has cells that are 16-inches in diameter, he said.

    The idea is to take these cells, stack them about 20 high, and link the stacks together in rows about 20 deep that that fit inside a 40-foot shipping container. This shipping-container-sized battery would provide about 2 megawatt hours of juice.

    By the end of 2014, the goal is "to have something that can be readily shipped to a potential customer for testing," Sadoway said.

    While the utility companies may be interested in the batteries as an alternative to gas-fired peaker plants to make their solar and wind farms viable, the batteries also could ease transmission line congestion.

    This could be particularly useful in tech-heavy regions such as the Bay Area, where the energy demands of server farms are steadily climbing, noted Sadoway.

    On certain days of the year, for example during a heat wave in the middle of the summer, "you can't get enough electricity through the lines. The transmission lines are running at full capacity," he said.

    Instead of building additional transmission capacity — bringing more wires into the city, which is usually controversial and requires a drawn-out permitting process — companies could plop a battery in the basement of their buildings.

    "From midnight to 5 a.m., when the lines aren't congested [and rates are low] you could be shipping electricity into the center of the city and storing it in the basement of these buildings," Sadoway explained. 

    "Then, in the middle of the day, you just take it right out of the basement into the servers."

    Kammen, the University of California energy professor, said this is "exciting stuff and a welcome area of long-overdue innovation."

    Updated at 1:40 pm PT to reflect comments from Daniel Kammen.

    More on battery and storage technology:

    John Roach is a contributing writer for msnbc.com. To learn more about him, check out his website and follow him on Twitter. For more of our Future of Technology series, watch the featured video below.

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  • Energy storage breakthroughs on the horizon

    Charlie Riedel / AP

    In this file photo, a group of 260-foot-high wind towers are silhouetted against a bright orange sky at the Elk River Wind farm near Beaumont, Kan. Massive integration of wind power to the electric grid will take breakthroughs in energy storage technologies.

    By John Roach, Contributing Writer, NBC News

    Breakthroughs in energy storage technologies are on the horizon that could turn vast swathes of the world's sun-soaked deserts and windy plains into sources of clean, renewable energy, according to experts focused on our energy future.

    No one technology — ranging from storing a portion of the sun's energy collected during the day in molten salt to run solar thermal generators at night to banks of lithium-ion batteries scattered around neighborhoods — will be the solution.

    Rather, "there is going to be a portfolio of energy storage" options, Bruce Dunn, a professor of materials science and engineering at the University of California at Los Angeles, told me Thursday. 

    Dunn is the lead author of a review paper in this week's issue of the journal Science that explores the prospects for three battery technologies to become cheap, reliable and efficient enough for wide-scale deployment on the electric power grid.

    Battery breakthroughs
    Lithium-ion battery technology, for example, is enjoying a boost in research and development for the electrical vehicle market that is driving down manufacturing costs. Utilities will piggyback on those improvements and may even be able to use EVs to store excess wind and solar energy, he noted.

    Other technologies such as redox-flow batteries are relatively new and unproven. "On paper it looks to be very inexpensive," he said, but there's very little experience using them at the scale utilities need.

    The batteries are based on the use of liquid electrolytes stored in tanks and pumped through a reactor to produce energy. 

    As it stands now, there's plenty known about how the batteries work on the small scale, but not much about how they work on large scale. Will they maintain the right power levels? Will there be corrosion problems?

    Answers to such questions should start to come within three or four years with preliminary results from demonstration projects supported by the Advanced Research Projects Agency-Energy and the Department of Energy.

    "It's an experiential thing, there's no way around it. You've got to build big stuff," Dunn said. "And those things are built and they are being tested. That's the good news."

    Sodium-sulfur batteries, the third technology in the Science review, are already in limited use by utilities around the world, including Japan where they are sold commercially, but the technology is costly, Dunn said. Manufacturing prices have to fall before they can be embraced.

    In time, he said, prices will fall, just as they have for technologies such as personal computers. And as prices for big, utility-scale batteries fall, they'll be incorporated onto the electric grid, allowing the integration of renewable sources of power such as wind and solar.

    The use of batteries on the grid will also reduce the need to construct generation capacity that sits idle most of the time but puts off excess emissions of greenhouse gases as they are cycled up and down to meet peak demands, the researchers note.

    Hydrogen storage
    Another way to store energy is in the form of hydrogen, which has long been eyed for the fuel cells that some believe will power most cars in the future. A hurdle is how to cheaply and efficiently get hydrogen, which is abundant but almost always bound to something else.

    One solution may come from researchers at the Massachusetts Institute of Technology who are working on so-called artificial leaf technology that splits water into bubbles of oxygen and hydrogen. The hydrogen can be stored and used to power fuel cells.

    Questions remain about how efficient the system is and how inexpensively they can generate hydrogen, notes Robert Service in a news story about the technology in Science. 

    One study, he noted, found that hydrogen can be produced from natural gas about half as cheaply using a mature technology called steam reforming than the best-case scenarios envisioned for the artificial leaf technologies.

    "That's not saying artificial photosynthesis isn't worth pursuing – only that fossil fuels are the leading energy source for a reason and they won't be easy to dethrone," he writes.

    More bang for the fossil fuel buck
    Eric Wachsman, a sustainable energy researcher at the University of Maryland, argues that technological improvements are making fuel cells that run on all types of fuels, including conventional fuels such as gasoline, in addition to hydrogen, a viable option everywhere from power grids to transportation.

    In separate Science review article, he explains that the breakthrough comes from new electrolyte materials that allow solid oxide fuel cells to be operated at lower temperatures.

    Solid oxide fuel cells such as Bloom Energy's device that was rolled out last year, he told me, have a power density of about 0.2 watts per square centimeter while operating at about 950 degrees Celsius. His team has developed a solid oxide fuel cell that gets 2 watts per square centimeter at 650 degrees Celsius.

    "It is an order of magnitude higher power density at a much lower temperature," he said, adding that his team has also developed electrolytes that make operation at 350 degrees Celsius viable.

    And if solid oxide fuel cells can operate at lower temperatures, they become attractive for use in transportation where using a fuel cell to power a car is two and a half to three times more efficient than using fuel to run an internal combustion engine, he noted.

    Wachsman is hoping the government will continue to support research in solid oxide fuel cell technology to help bring down the costs and scale up the technology, though noted the prospects are grim.

    "There is no funding for solid oxide fuel cells in the current DOE budget," he said.

    The dearth of government funding for energy innovation is taken up by Bill Gates, Microsoft chairman and co-chair of the Bill and Melinda Gates Foundation, in a Science editorial that plugs his call to increase R&D spending from $5 billion to $16 billion a year.

    "History has repeatedly proven that federal investments in research return huge payoffs with incredible associated benefits for U.S. industries and the economy," he writes. "Yet over the past three decades, U.S. government investment in energy innovation has dropped by more than 75 percent."

    Without further government investment, will the needed breakthroughs in energy storage remain on the horizon?

    More stories about energy technology:

    John Roach is a contributing writer for msnbc.com. To learn more about him, check out his website. For more of our Future of Technology series, watch the featured video below.

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  • Battery tech improving as demand soars

    Department of Energy

    Transmission electron microscopy reveals the new conducting polymer's improved binding properties. At left, silicon particles embedded in the binder are shown before cycling through charges and discharges (closer view at bottom). At right, after 32 charge-discharge cycles, the polymer is still tightly bound to the silicon particles.

    By John Roach, Contributing Writer, NBC News

    The ability of rechargeable lithium-ion batteries to store up to eight times more energy than conventional designs is getting a boost thanks to a new conducting material that doesn't break down after repeated usage. 

    What's more, the manufacturing process is compatible with established technologies, according to researchers with the Department of Energy's Lawrence Berkeley National Laboratory in California. 

    Lithium-ion batteries are found everywhere from laptop computers and hybrid cars to electric power grids. The market for them is expected to soar by a factor of more than 80 between 2012 and 2020, rising to $5.8 billion a year, according to a new report from research firm IHS. 

    That's primarily because the batteries are likely to be integrated with gusto to the so-called "smart grid" that increasingly relies on intermittent technologies such as solar and wind energy. Batteries provide a place to store energy when excess is generated and deliver it when it's needed. 

    "Because of this, lithium ion is set to emerge as the dominant rechargeable battery technology for electrical smart grids during the coming years," Satoru Oyama, principal analyst for Japan electronics research at IHS, said in a statement.

    A limitation of lithium-ion batteries, though, is the amount of energy they are able to store. Researchers have identified silicon as a material that can store 10 times more energy than conventional technology, but it swells more than three times its volume when fully charged then shrinks again during discharge.

    This swelling and shrinking, according to the DOE, quickly breaks down the electrical contacts in the anode, rendering the battery ineffective. This sent Gao Liu and colleagues at the Berkeley lab looking for an anode that can stay in contact with lithium-storing silicon particles. 

    They ended up developing a polymer that does just this. The new anode can absorb eight times the lithium of current designs and, in more than a year of testing and many hundreds of charge-discharge cycles, it hasn't broken down. 

    The team reports the breakthrough in the journal Advanced Materials.

    More stories on battery technology

    John Roach is a contributing writer for msnbc.com.

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  • See-through battery in the works

    Stanford University

    Researchers have created a transparent battery that can be used to power gadgets such as smartphones and laptops.

    By John Roach, Contributing Writer, NBC News

    Imagine a smartphone that looks like a piece of clear plastic, lighting up to display contacts, a game, the weather, or email from a friend. That future may be upon us thanks to a new, transparent and flexible lithium-ion battery.

    Lithium-ion batteries are the type of energy storage devices that power consumer electronics such as smartphones. 

    Transparent components of gadgets such as touch screens, displays, and optical circuits have been fabricated, but until now, batteries have prevented fully see-through gadgets from entering the marketplace because the materials used to make batteries are not see-through.

    "If you look at a battery electrode, it is black, it is not transparent," Yi Cui, a nanomaterials science and engineering researcher at Stanford University, told me today. 

    Cui, who has used nanoscale manufacturing techniques for other battery breakthroughs, and his colleagues overcame this hurdle by fabricating a battery with visible parts below the resolution of human eyes.

    To do this, they spin-coated a silicon substrate with nanoscale-sized, grid-like trenches that were filled with an active electrode material via capillary forces. 

    "When the line widths of this grid is smaller than the size that your eye can resolve, they will look transparent," Cui said.

    A paper describing the battery was published today in Proceedings of the National Academy of Sciences.

    The authors add that by aligning multiple batteries together in a series, the overall energy stored can be increased without sacrificing transparency. The battery is also fully flexible, broadening its potential applications. 

    That futuristic smartphone, Cui said, is possible today. "There is no barrier going forward," he said. "You have a cell phone case that is transparent and then everything inside is transparent including the battery."

    More on batteries and transparency:

    John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).