Solar power plant based on molten salt

"Hamilton Sundstrand, a division of United Technologies, announced today that it will start to commercialize a new type of solar power plant. A new company called SolarReserve will be created to provide heat-resistant pumps and other equipment, as well as the expertise in handling and storing salt that has been heated to more than 1,050 degrees Fahrenheit. According to venture capitalist Vinod Khosla 'Three percent of the land area of Morocco could support all of the electricity for Western Europe.' Molten Salt storage is already used in Nevada's Solar One power plant. Is this the post-hydrocarbon world finally knocking?"

Solar power might be the most up-and-coming renewable energy source, but one of the biggest drawbacks to solar power plants is their inability to generate electricity at night or during cloudy days. But now, a new venture called SolarReserve hopes to change all that using salt! Their program would save and store captured solar energy in molten salt, the new solar plant will produce up to 500 megawatts of peak power — comparable to what a regular coal power plant can produce, only with no greenhouse gas emissions.

Unlike other solar power plants, SolarReserve’s will be able to produce electricity at night or in inclement weather. You can see the commercial potential here if you note that just one megawatt is enough power roughly 1,000 U.S. households. The company hopes to build 10 plants over the next 10 to 15 years.

The concept behind new concentrated solar power plant is very similar to Seville’s solar power tower where hundreds of solar panels reflect the sun’s light to heat the water inside the tower, which later evaporates into steam that passes through series of turbines to generate electricity. However, instead of tower that holds water, SolarReserve’s holding tank will have molten salt. Huge array of mirrors will reflect light onto the tank; heated 1,000 degrees Fahrenheit liquid is then pumped into a steam generator that will turn a turbine to make electricity.

“Due to the unique ability of the product to store the energy it captures, this system will function like a conventional hydroelectric power plant, but with several advantages,” says Lee Bailey, managing director of US Renewables Group, SolarReserve parent company. “This product is more predictable than water reserves, the supply is free and inexhaustible, and the environmental impact is essentially zero.”

SolarReserve says that their use of molten salt, a mixture of sodium and potassium nitrate, instead of water or oil, allows the heat to be stored for use when sun is not present. The National Solar Thermal Test Facility conducted several studies and concluded that molten salt is the most efficient fluid when it comes to transporting sun’s heat. The study states, “molten salt is used in solar power tower systems because it is liquid at atmosphere pressure, it provides an efficient, low-cost medium in which to store thermal energy, its operating temperatures are compatible with today’s high-pressure and high-temperature steam turbines, and it is non-flammable and nontoxic.”

+ SolarReserve (US Renewables Group, parent company)

ref:http://www.inhabitat.com/2008/01/14/energy-breakthrough-storing-solar-power-with-salt/

electronic stethoscope power by uCLinux

A team of engineering students at Calvin College in Grand Rapids, Mich. is designing a digital stethoscope based on uClinux. The team, called "Rhythm Reloaded," released a project proposal on the open source device, which runs Freescale's Coldfire MCF5275 CPU.

The Rhythm Reloaded team is building the stethoscope as part of a senior design project. The team hopes its device will be the first electronic stethoscope able to record, filter, and store computer audio data from a medical patient.

The Rhythm Reloaded team hopes its design can improve upon traditional acoustic analog designs, by offering reduced ambient noice and higher recording quality. Audio files will use a format convenient for transfer to PCs via a USB interface.


Conceptual diagram of the Rhythm Reloaded stethoscope

In addition to the Coldire MCF5275 CPU, the device is equipped with a Crystalfontz 16x2 STN backlit LCD module, button interfaces, a Wolfson WM8731 audio codec, an electret microphone, and flash storage, all powered by a rechargeable Li-Ion battery.


Rhythm Reloaded team (left to right): Nathan Brinks, Ben Moes, Andy Gabler, David van Geest

Rhythm Reloaded's project proposal and feasibility study offers an instructive example of the complex planning and decision-making required to build a relatively simple embedded Linux device. The team steps the reader through each decision, detailing the many debates in selecting a physical design, operating system, distribution, microprocessor, storage medium, I/O, microphone, and more.

For example, the team had originally considered wireless technologies such as Bluetooth or Wireless USB, but decided these options added too much expense and could cause configuration problems. Wireless technologies also raised potential patient privacy concerns, and required more expensive cryptography, so they opted for USB instead.

For audio processing, the students decided that instead of using low-cost ADCs and DACs, they would go with a more expensive hardware codec due to its greater audio resolution. Interestingly, they decided on a Wolfson WM8731 codec instead of slightly better performing Analog Devices and NXP codecs, because the Wolfson was much better documented.


Rhythm Reloaded stethoscope block diagram
(Click to enlarge)
The team conducted an in-depth analysis on whether to go with a microprocessor, ASICs, FPGAs (field programmable gate arrays), or FPGAs with softcores. In the end they decided on a microprocessor due to factors such as ease of development, availability, and greater hardware abstraction capabilities. After winnowing the field based on a list of requirements, they chose a Freescale's Coldfire MCF5275 CPU, in part because the company donated an evaluation board to the project.

In choosing the operating system, the Rhythm Reloaded team quickly decided they wanted an open source OS because, as students, they needed the expertise and development resources of an open source community. They decided on Linux and specifically uClinux, a small-footprint variant of the Linux kernel targeting resource-constrained embedded applications. The team compiled the kernel using the GNU 68K/Coldfire C/C++ toolchain.

In explaining its OS choices, the team wrote in the proposal, "The Linux kernel is known to be secure, and it robustly handles multiple processes. Furthermore, because of its wide adoption in the embedded market, several different third-party software vendors provide Eclipse-based IDEs specifically for uClinux, and one of those vendors has donated a software license to the team."

Should Rhythm Reloaded ever decide to develop the device for the commercial market, it will face additional challenges, such as FDA validation. Yet, if nothing else, they will have learned -- and shared -- some valuable lessons in embedded design.

The proposal and other project details may be available here.

bionic contact lens with overlay display

University of Washington is developing a new contact lens, that can give overlay display. Just like in movie Terminator, where the person could see some overlay text messages in his eye. So its no more a fiction.


Off the screen, virtual displays have been proposed for more practical purposes -- visual aids to help vision-impaired people, holographic driving control panels and even as a way to surf the Web on the go.

The device to make this happen may be familiar. Engineers at the UW have for the first time used manufacturing techniques at microscopic scales to combine a flexible, biologically safe contact lens with an imprinted electronic circuit and lights.

"Looking through a completed lens, you would see what the display is generating superimposed on the world outside," said Babak Parviz, a UW assistant professor of electrical engineering. "This is a very small step toward that goal, but I think it's extremely promising." The results were presented today at the Institute of Electrical and Electronics Engineers' international conference on Micro Electro Mechanical Systems by Harvey Ho, a former graduate student of Parviz's now working at Sandia National Laboratories in Livermore, Calif. Other co-authors are Ehsan Saeedi and Samuel Kim in the UW's electrical engineering department and Tueng Shen in the UW Medical Center's ophthalmology department.

There are many possible uses for virtual displays. Drivers or pilots could see a vehicle's speed projected onto the windshield. Video game companies could use the contact lenses to completely immerse players in a virtual world without restricting their range of motion. And for communications, people on the go could surf the Internet on a midair virtual display screen that only they would be able to see.

"People may find all sorts of applications for it that we have not thought about. Our goal is to demonstrate the basic technology and make sure it works and that it's safe," said Parviz, who heads a multi-disciplinary UW group that is developing electronics for contact lenses.

The prototype device contains an electric circuit as well as red light-emitting diodes for a display, though it does not yet light up. The lenses were tested on rabbits for up to 20 minutes and the animals showed no adverse effects.

Ideally, installing or removing the bionic eye would be as easy as popping a contact lens in or out, and once installed the wearer would barely know the gadget was there, Parviz said.

Building the lenses was a challenge because materials that are safe for use in the body, such as the flexible organic materials used in contact lenses, are delicate. Manufacturing electrical circuits, however, involves inorganic materials, scorching temperatures and toxic chemicals. Researchers built the circuits from layers of metal only a few nanometers thick, about one thousandth the width of a human hair, and constructed light-emitting diodes one third of a millimeter across. They then sprinkled the grayish powder of electrical components onto a sheet of flexible plastic. The shape of each tiny component dictates which piece it can attach to, a microfabrication technique known as self-assembly. Capillary forces -- the same type of forces that make water move up a plant's roots, and that cause the edge of a glass of water to curve upward -- pull the pieces into position.

The prototype contact lens does not correct the wearer's vision, but the technique could be used on a corrective lens, Parviz said. And all the gadgetry won't obstruct a person's view.

"There is a large area outside of the transparent part of the eye that we can use for placing instrumentation," Parviz said. Future improvements will add wireless communication to and from the lens. The researchers hope to power the whole system using a combination of radio-frequency power and solar cells placed on the lens, Parviz said.

A full-fledged display won't be available for a while, but a version that has a basic display with just a few pixels could be operational "fairly quickly," according to Parviz.

The research was funded by the National Science Foundation and a Technology Gap Innovation Fund from the UW.

ref:http://uwnews.org/uweek/uweekarticle.asp?visitsource=uwkmail&articleID=39100