Tuesday, February 17, 2015

Storing (Renewable) Energy using Air Compressors

Lightsail: http://www.lightsail.com/

From http://www.greentechmedia.com/articles/read/LightSail-Energy: The LightSail system captures and stores both the mechanical energy and the thermal energy used in compressing air.

To do this, a water mist is infused into the compression chamber as the air is compressed. Water can hold 3,300 times as much heat as the same volume of air, and as such, it is able to capture the heat generated by the process more effectively. Both potential energy in the form of pressurized air and the heated (and therefore higher-energy) water can be stored.

When the captured, pressurized air is released back through the system, the heated water is re-infused into it. That heated air can return more of the energy stored by the system than can other CAES processes.


  • http://www.nantucketproject.com/danielle_fong_a_time_for_urgency
  • http://www.lightsail.com/blog/making-economical-clean-energy-at-planet-scale/
  • Friday, November 30, 2012

    Printable organic photovoltaic solar cells with 9.2% efficiency

    From a Phillips66 press release:
    HOUSTON, August 21, 2012 – Phillips 66 (NYSE:PSX) South China University of Technology (SCUT), and Solarmer Energy, Inc. have successfully set a new world record in power conversion efficiency for polymer-based organic photovoltaic (OPV) cells. The 9.31 percent efficiency was certified by the Newport Technology & Application Center’s Photovoltaic Lab in Long Beach, Calif.

    “The breakthrough in efficiency offers a good opportunity for the commercialization of the organic photovoltaic technology,” said Dr. Byron Johnson, manager of Sustainability Technologies at Phillips 66. “This marks an important milestone for the industry and has the potential to deliver truly low cost energy for the world.”


    As a bonus, the researchers also demonstrated that the design works for making semi-transparent inverted PSCs, which might be used in windows, curtains, and invisible electronic circuits. Further, the researchers have calculated that their new design could reach the 10% target by making some reasonable improvements. By collaborating with Phillips 66 and Solarmer, they hope to bring the first OPV products to the market some time next year.

    From PhysOrg Although silicon solar cells have efficiencies climbing above 20%, the researchers emphasize that OPV's low-cost production will make them competitive with the more expensive silicon cells. However, the plastic-based OPVs have had to overcome another problem in order to attract commercial interest: low stability that leads to short lifetimes. This problem stems in part from the cathode, which is often made of a reactive metal that easily oxidizes in air. Although encapsulating the cathode can minimize degradation, researchers have discovered that they can completely eliminate the need for this reactive metal by inverting the device architecture. In an inverted cell, the electric charges exit the device in the opposite direction as in a normal device. This happens because the positive and negative electrodes (which absorb the negative and positive charges, respectively) are reversed. Inverting the device architecture allows researchers to make the cathode out of a more suitable material; in this case, the researchers used indium tin oxide (ITO) modified with the polymer PFN.

    Affordable solar cell technology based on Copper, Zinc and Tin

    From engadget: There have been more than a few solar power efficiency records set in the past few months, let alone years. What makes IBM, DelSolar, Solar Frontier and Tokyo Ohka Kogyo think they can just waltz in and claim a record of their own? By using more commonplace elements in the periodic table, that's how. The partnership's new photovoltaic cell based on copper, zinc and tin (CZTS for short) can convert light rays to electric power with a 11.1 percent efficiency rate -- still nothing to upset traditional silicon power, but a large 10 percent more efficient than anything else in the class. In its early form, CZTS can already be manufactured through ink printing and could be produced in quantities equivalent to about 500 gigawatts of power per year, or five times more than some of the next-closest alternatives. The group wants to improve CZTS' efficiency over the course of the next several years, ideally reaching the point where it's useful as a truly cheap, ubiquitous source of power.

    Thursday, December 15, 2011

    First 20MW Flywheel Energy Storage plant in full commercial operation

    Beacon Power announced earlier this year that "The world's first 20 MW flywheel energy storage plant, designed, built and operated by Beacon Power in Stephentown, New York, reached full capacity on June 21, 2011. The plant operates continuously, storing and returning energy to the grid to provide approximately 10% of the state's overall frequency regulation needs."

    So why is this important? First, a bit of background info:
    From renewableenergyworld.com:
    Energy storage technologies are often referred to as a way to shift time and smooth the delivery of renewable energy such as wind and solar. But the cost of energy storage infrastructure is not insignificant. Today's cost for advanced lithium batteries (one of the leading energy storage candidates) capable of storing 1 MWh of electricity is about $2 million, about the same capital cost per megawatt-hour as the wind turbine. So if a 1 MW-rated turbine has good wind and is able to produce its megawatt hour rating for 10 hours it will produce 10 MWh of energy. Storing this energy would require $20 million worth of batteries. This obviously is not an economic model.
    The need for frequency regulation is the main reason that power generators have to match supply to demand. It would sometimes be easier simply to create more electricity than is being demanded. But this is more dangerous than not supplying enough electricity. When there is more supply of electricity than is demanded the frequency of the alternating current goes above 60 Hz and when the supply is exceeded by demand the frequency drops below 60 Hz. (In Europe and other parts of the world this standard is 50 Hz.) Electric companies are mandated by federal laws to maintain 60 Hz on the grid. The bigger the disparity above or below 60 Hz the larger the fines that may be imposed on them.

    Power companies are used to having a deterministic supply side. If they tell a supplier to fire up a turbine that is rated for 30 MW they can count on having 30 MW delivered within the contracted time with near certainty. With wind and solar energy, however, we are now asking the power company to deal with intermittency on their supply side and not just on their demand side. Although renewable energy sources (not counting hydroelectricity) account for less than 2 percent of the total energy generated in the United States, the popular press and politicians are talking about having 20 percent of our electricity generated by renewables within 10 years. Common sense suggests that load following and frequency regulation will become more difficult and expensive with this increase in supply side variability.

    But why flywheels? And how does that work, anyways? From greenpowerresearch.com:A flywheel is a mechanical device with a significant moment of inertia used as a storage device. Flywheel Energy Storage (FES), also referred to as kinetic storage. The flywheels inertial mass is accelerated to a very high rotational speed and the energy in the system is maintained as rotational energy. The energy is converted back as needed to the desired application by slowing down the flywheel. In short, energy is stored in the rotor as rotational energy. The stored energy in a flywheel is proportional to the mass, and to the square of the tip velocity. Key features of flywheel-based regulation are its fast response (many times faster than conventional fossil fuel generators used for regulation); its high round trip efficiency (85 percent); and the fact that it produces zero direct CO2 or other emissions.

    Yingli Green Energy is also working on this type of technology. From Asia Today: On September 29, the experiment sample of China's first 20 kilowatt-hour magnetic suspension energy-storage flywheel, developed by Yingli independently, was completed. This revealed some clues about the next strategic goals of Yingli. This kind of energy storage technology is a key for new energies to evolve from substitute energies into mainstream energies.

    There are other applications for flywheel energy storage as well. For example, on Sept 1, 2011, Kinetic Traction Systems and Williams Grand Prix Engineering Limited (Williams F1)
    announced that they have signed a long-term Co-operation Agreement to advance and promote innovative, clean flywheel-based energy storage and recycling systems for mass transit rail and grid applications.

    Originally intended for use in the Kinetic Energy Recover Systems of its racing cars, Williams F1's subsidiary, Williams Hybrid Power (WHP) has developed high-performance, lightweight mobile flywheel energy storage systems. These incorporate its patented Magnetic Loaded Composite (MLC) technology which gives the systems their unique high cycling ability and high-power characteristics. WHP's mobile flywheel systems have been successfully applied in applications such as the Porsche 911 GT3 R hybrid.

    KTSi's proprietary stationary GTR flywheel systems, which leverage WHP's MLC technology, capture braking energy of trains to increase performance, reduce electrical energy consumption, and lower carbon emissions for metro transit agencies around the globe.


    From the Alternative Energy Stocks blog: Hype Busters From Lux Research Explain Grid Based Energy Storage

    Friday, February 16, 2007

    28% Sunlight-to-Electricity Conversion Effiency

    PYRON SOLAR INC,  in cooperation with Boeing-Spectrolab has developed a highly cost-effective concentrating solar technology to convert sunlight into electricity.
    Concentrated photovoltaic — or CPV — systems continuously track the sun, capturing sunlight and converting it into highly concentrated solar energy. ... Pyron Solar, a Vista-based CPV startup, uses water to support its array so that the system actually floats, helping to cool the array and make it more efficient.
    CPV as an industry is an emerging field and has yet to become commercially viable. It also has some location requirements — it works well only in regions with high, direct sunlight. And Pyron’s use of water makes for a niche within that segment.
    Pyron, founded in 2006, uses an acrylic concentrator lens with precise circular grooves that magnify sunlight and raise the concentration by 1,200 times, or the equivalent of 1,200 suns.
    ... The new version, which has an efficiency (the percentage of sunlight it converts into energy) of 28 percent, can better withstand wear and tear, is corrosion resistant even with salt water, prevents water leaks and has improved weatherproofing.

    Wednesday, February 01, 2006

    Printable Solar Cells

    nanosolar Printable Solar Cells
    This looks pretty cool - solar power you can roll out like roofing material. Could really open up the market for locally generated solar power. From the company's website:
    Nanosolar has developed the world's most cost-efficient solar electricity technology and is working to bring it to customers everywhere and capture a significant fraction of the world’s electricity generation.

    Improving the cost of solar electricity means optimizing power-conversion performance (W/sqft), product cost ($/sqft), lifetime (years), as well as other system and installation costs ($) – and the optimum of this is generally not the maximum of any individual dimensions. (For instance, the highest efficiency does not necessarily result in the lowest cost.) In addition, addressing the market in volume requires scalable production and technology with robust high yield and low capital expenditures ($/MW).

    Conventional solar electricity systems based on crystalline silicon wafers have succeeded in meeting the first several billion dollars of annual market need for solar electricity systems. But the industry is finding it increasingly difficult to further optimize products based on the inherently stiff amounts of material and energy required, as well as production fundamentally limited by processes based on moving batches of fragile wafers and/or glass plates through a factory.

    In order to make solar electricity scale beyond the limitations found with crystalline silicon, substantial amounts of R&D have been invested over the past two decades into novel kinds of approaches based on much thinner and more easily processable solar cells. These thin-film cells are based on non-silicon semiconductors (inorganic semiconductors of the IIb/VIa and Ib/IIIa/VIa families as well as solution-coatable organic semiconductors) which can absorb the same amount of sunlight as crystalline silicon but in layers that are at least two orders of magnitude thinner.

    Designed to be easily installed on large low-slope rooftops or directly integrated with leading commercial roofing membrane products (such as single-ply thermoplastic membranes), customers can save on installation and achieve even lower total system cost.

    With multiple SolarPly™ sheets readily interconnected, large areas of sunpower collection and electricity generation can be easily created. Nanosolar has developed reference designs and mounting mechanism for all of the most common types of building structures.

    The University of Toronto has developed a 'spray on' solar collection material that is capable of capturing energy in the infra red spectrum. “We made particles from semiconductor crystals which were exactly two, three or four nanometres in size. The nanoparticles were so small they remained dispersed in everyday solvents just like the particles in paint,” explains Sargent. Then, they tuned the tiny nanocrystals to catch light at very long wavelengths. The result – a sprayable infrared detector.

    Existing technology has given us solution-processible, light-sensitive materials that have made large, low-cost solar cells, displays, and sensors possible, but these materials have so far only worked in the visible light spectrum, says Sargent.
    Professor Peter Peumans of Stanford University, who has reviewed the U of T team’s research, also acknowledges the groundbreaking nature of the work. “Our calculations show that, with further improvements in efficiency, combining infrared and visible photovoltaics could allow up to 30 per cent of the sun’s radiant energy to be harnessed, compared to six per cent in today’s best plastic solar cells.”

    Smart venetian blinds - 30% efficient solar collection, and it looks great too!

    Tuesday, January 03, 2006

    Wind power

    Technically, wind is a form of solar power that has already been converted into mechanical power.

    From the Sept. 1990 Issue of Scientific American:
    About 90% of the wind power potential of the U.S. is in 12 contiguous states, where large scale ranching and grain producction are major industries. Wind power could be a good neighbor to such agricultural activities. Experience shows that the value of ranchland increases rapidly when it is converted to wind farms, while using only around 5% of the grazing area since cattle can continue to graze around the wind turbines".

    From Canadian Geographic:
    Since 200 bc, when windmills were used to pump water in China and grind grain in Persia, wind has been providing power to the people. Wind is the world's fastest-growing energy source increasing by some 24 percent a year over the past decade. Approximately 20 percent of Denmark's electricity comes from wind, with the goal of reaching 50 percent by 2030. Parts of Germany and Spain are producing 14 and 22 percent, respectively, and India, China and Argentina are making advances. Alberta alone has enough wind potential to power up three million homes.

    From Wired Magazine:
    (May 22, 2005)
    Wind power could generate enough electricity to support the world's energy needs several times over, according to a new map of global wind speeds that scientists say is the first of its kind.

    The map, compiled by researchers at Stanford University, shows wind speeds at more than 8,000 sites around the world. The researchers found that at least 13 percent of those sites experience winds fast enough to power a modern wind turbine. If turbines were set up in all these regions, they would generate 72 terawatts of electricity, according to the researchers. That's more than five times the world's energy needs, which was roughly 14 terawatts in 2002, according to the U.S. Department of Energy.

    Full-size image

    Global wind map identifies wind power potential
    Wind turbines a breeze for migrating birds

    Monday, December 05, 2005

    What we need is a solar powered technofix...

    I was sad to read recently that Richard Smalley had passed away. ( news article ). He shared the Nobel Prize for the discovery of Buckminsterfullerene, the atomic geodesic sphere that has led to the creation of carbon nanotubes, the stuff that is poised to revolutionize everything from batteries to solar cells to display technology to nanoelectronics.

    I came across Smalley's efforts to champion the development of solar power earlier this year. (paper: "Future Global Energy Prosperity: The Terawatt Challenge", video of speech given at Columbia is available online at http://smalley.rice.edu/). It's a compelling, coherent vision of what we need to do over the next 20 years in order to re-invent the world in a very postive way.

    "There is plenty of energy hitting the surface of the earth. Nate Lewis of the California Institute of Technology likes to demonstrate that we could cleanly meet the world’s entire energy needs, two kilowatts per person for 10 billion people by applying the following elegant solution: On a global map, identify six rectangular space located in areas of high solar radiation, create a 10% effiencg [solar collection technology], then collect that power, which would be about 20 terawatts of electrical power. That would totally solve humanity's energy problem."

    When I first read this, I immediately thought of another article I'd previously come across that outlines some very promising work being done on Stirling engines ( link to article ).

    PORTLAND, Ore. — Electrical Engineers are turning a 19th-century invention into a 21st-century alternative-energy source.

    The last leg of a two-decades-long effort by the U.S. Energy Deaprtment to unleash superefficient solar power by 2011 is homing in on the so-called Stirling engine, which is being used to drive solar generators. DOE test site measurements suggest the setup could bring the cost of solar power on a par with traditional fossil fuels and hydroelectric sources — assuming the project engineers can balance the separate power feeds from farms of thousands of simultaneously online 25-kilowatt Stirling solar dishes.

    The heart of the design, the engine itself, was invented by the Scottish minister Robert Stirling in 1816.

    "The Stirling engine makes solar power so much more efficiently than photovoltaic solar cells can," said Robert Liden, chief administrative officer at Stirling Energy Systems Inc. (Phoenix). "That's because the Stirling solar dish directly converts solar heat into mechanical energy, which turns an ac electrical generator." The bottom line, he said, "is that large farms of Stirling solar dishes — say, 20,000-dish farms — could deliver cheap solar electricity that rivals what we pay for electricity today."

    Under a multiyear Energy Department contract that started in 2004, Stirling Energy Systems will supply Sandia National Laboratories with solar dishes for integration into full-fledged power-generation substations capable of direct connections to the existing U.S. power grid. Right now about 20 EEs, including more than a dozen from Stirling Energy Systems, are working full time at Sandia to create the electrical-control systems to manage these sunshine stations.

    By the end of 2005, they plan to have six dishes connected into a miniature power station capable of supplying enough 480-volt three-phase electricity to power about 40 homes (150 kW). The next step, in 2006, is a 40-dish power plant that will transform the combined output of the farm from 480 to 13,000 V, for distribution of industrial-level power to an existing substation. From 2007 to 2010, the program proposes mass-producing dishes to create a 20,000-dish farm supplying 230,000 V of long-haul power from its own substation directly connected to the grid.

    If the project succeeds, the DOE predicts that by 2011, Stirling solar-dish farms could be delivering electricity to the grid at costs comparable to traditional electricity sources, thereby reducing the U.S. need for foreign sources of fossil fuels.
    Today Stirling-powered solar dishes at the Sandia test facility operate at 30 percent efficiency while delivering grid-ready alternating current. In contrast, 30-percent-efficient solar cells are direct current and drop to 16 percent efficiency by the time they generate grid-ready ac. And that's on a hot day. Efficiency can drop as low as 10 percent on a cool day.

    "Tests have already shown that the Stirling engine can be made into a very efficient power generator," said Chuck Andraka, project leader at Sandia's Solar Technology Department. "Now what we need to show is that many small Stirling engines can be coordinated in farms that together rival traditional power sources."

    Eventually, according to DOE estimates, an 11-square-mile farm of Stirling solar dishes could generate as much electricity as the Hoover Dam, and a 100 x 100-mile farm could supply all the daytime needs for electricity in the United States. By storing the energy in hydrogen fuel cells during the day, Stirling solar-dish farms could supply U.S. electrical-energy needs at night too, as well as enough juice for future fuel-cell-powered automobiles, the DOE believes.

    (See also the news release from Sandia National Laboratories)

    Why is this stuff not a global priority? It offers so much hope for the future, something the world needs badly right now.