Sonnenschiff: Solar City Produces 4X the Energy it Consumes

by Andrew Michler

 

 

Although net-zero projects have been creating a lot of buzz lately in the field of green building, the Sonnenschiff solar city in Freiburg, Germany is very much net positive. The self-sustaining city accomplishes this feat through smart solar design and lots and lots of photovoltaic panels pointed in the right direction. It seems like a simple strategy -- but designers often incorporate solar installations as an afterthought, or worse, as a label. Designed byRolf Disc, the Sonnenschiff (Solar Ship) and Solarsiedlung (Solar Village) emphasize power production from the start by smartly incorporating a series of large rooftop solar arrays that double as sun shades. The buildings are also built to Passivhaus standards, which allows the project to produce four times the amount of energy it consumes!

  

The project started out as a vision for an entire community — the medium-density project balances size, accessibility, green space, and solar exposure. In all, 52 homes make up a neighborhood anchored to Sonnenschiff, a mixed-use residential and commercial building that emphasizes livability with a minimal footprint. Advanced technologies like phase-change materials and vacuum insulation significantly boost the thermal performance of the building’s wall system.

 

The homes are designed to the Passivhaus standard and have great access to passive solar heating and daylight. Each home features a very simple shed roof with deep overhangs that allows winter sun in while shading the building from the summer sun. The penthouses on top of the Sonnenschiff have access to rooftop gardens that make full use of the site’s solar resources. The rooftops feature rainwater recycling systems that irrigate the gardens and while supplying the toilets with greywater. The buildings also make use of wood chip boilers for heat in the winter, further decreasing their environmental footprint.
The project’s simple envelope design is brightened by a colorful and dynamic façade. Gardens and paths cross through the development as well, linking the inhabitants. Offices and stores expand the livability of the community while contributing a sense of communal purpose.

80% Cheaper Solar Cells Switch Gold For Nickel

by Brit Liggett

One of the major drawbacks of most renewable energy sources is high cost. In order to see a huge rise in the use of renewable energy sources, prices must come down. In the world of solar there have recently been some major breakthroughs in cost advantages and efficiency increases. Scientists at the University of Toronto in Canada have come up with a way to reduce colloidal quantum dot solar cell prices by up to 80%, by swapping out costly conductive gold for cheap nickel.



Quantum dot solar cells consist of a silicon substrate that has a thin film coating of nanocrystals — or quantum dots. Gold was previously used as the conductive material in the cells and when scientists tried to switch the gold out for nickel the nickel formed new particles with the quantum dots that weren’t able to capture energy. Scientists at the University of Toronto led by Dr. Ratan Debnath found that increasing the layer of silicon substrate created a big enough barrier between the dots and the nickel that the solar cells became effective at the expected efficiency levels.
The team at University of Toronto published their findings in a paper in the July 12, 2010 issue of Applied Physics Letters and noted that with further research they believe that they will be able to increase the efficiency of their extremely inexpensive quantum dot solar panels and make them look attractive to consumers when they eventually hit the market. Unlike conventional solar panels, the quantum dot solar cells that the University of Toronto invented capture visible and infrared light. Though a mode for large scale production still hasn’t been found the impacts of these super-cheap cells could be huge.

 

 

New solar energy conversion process could revamp solar power production

New solar energy conversion process could revamp solar power production

A small PETE device made with cesium-coated gallium nitride glows while being tested inside an ultra-high vacuum chamber. The tests proved that the process simultaneously converted light and heat energy into electrical current. Credit: Photo courtesy of Nick Melosh, Stanford University

Stanford engineers have figured out how to simultaneously use the light and heat of the sun to generate electricity in a way that could make solar power production more than twice as efficient as existing methods and potentially cheap enough to compete with oil.

Unlike photovoltaic technology currently used in solar panels - which becomes less efficient as the temperature rises - the new process excels at higher temperatures.

Called 'photon enhanced thermionic emission,' or PETE, the process promises to surpass the efficiency of existing photovoltaic and thermal conversion technologies.
"This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak," said Nick Melosh, an assistant professor of materials science and engineering, who led the research group. "It is actually something fundamentally different about how you can harvest energy."
And the materials needed to build a device to make the process work are cheap and easily available, meaning the power that comes from it will be affordable.
Melosh is an assistant professor of materials science and engineering, and is senior author of a paper describing the tests the researchers conducted. It was published online August 1, in Nature Materials.
"Just demonstrating that the process worked was a big deal," Melosh said. "And we showed this physical mechanism does exist, it works as advertised."
Most photovoltaic cells, such as those used in rooftop solar panels, use the semiconducting material silicon to convert the energy from photons of light to electricity. But the cells can only use a portion of the light spectrum, with the rest just generating heat.
This heat from unused sunlight and inefficiencies in the cells themselves account for a loss of more than 50 percent of the initial solar energy reaching the cell.
If this wasted heat energy could somehow be harvested, solar cells could be much more efficient. The problem has been that high temperatures are necessary to power heat-based conversion systems, yet solar cell efficiency rapidly decreases at higher temperatures.
Until now, no one had come up with a way to wed thermal and solar cell conversion technologies.
Melosh's group figured out that by coating a piece of semiconducting material with a thin layer of the metal cesium, it made the material able to use both light and heat to generate electricity.
"What we've demonstrated is a new physical process that is not based on standard photovoltaic mechanisms, but can give you a photovoltaic-like response at very high temperatures," Melosh said. "In fact, it works better at higher temperatures. The higher the better."
While most silicon solar cells have been rendered inert by the time the temperature reaches 100 degrees Celsius, the PETE device doesn't hit peak efficiency until it is well over 200 degrees C.
Because PETE performs best at temperatures well in excess of what a rooftop solar panel would reach, the devices will work best in solar concentrators such as parabolic dishes, which can get as hot as 800 degrees C. Dishes are used in large solar farms similar to those proposed for the Mojave Desert in southern California and usually include a thermal conversion mechanism as part of their design, which offers another opportunity for PETE to help generate electricity, as well as minimizing costs by meshing with existing technology.
"The light would come in and hit our PETE device first, where we would take advantage of both the incident light and the heat that it produces, and then we would dump the waste heat to their existing thermal conversion systems," Melosh said. "So the PETE process has two really big benefits in energy production over normal technology."
Photovoltaic systems never get hot enough for their waste heat to be useful in thermal energy conversion, but the high temperatures at which PETE performs are perfect for generating usable high temperature waste heat. Melosh calculates the PETE process can get to 50 percent efficiency or more under solar concentration, but if combined with a thermal conversion cycle, could reach 55 or even 60 percent - almost triple the efficiency of existing systems.
The team would like to design the devices so they could be easily bolted on to existing systems, making conversion relatively inexpensive.
The researchers used a gallium nitride semiconductor in the 'proof of concept' tests. The efficiency they achieved in their testing was well below what they have calculated PETE's potential efficiency to be, which they had anticipated. But they used gallium nitride because it was the only material that had shown indications of being able to withstand the high temperature range they were interested in and still have the PETE process occur.
With the right material - most likely a semiconductor such as gallium arsenide, which is used in a host of common household electronics - the actual efficiency of the process could reach up to the 50 or 60 percent the researchers have calculated. They are already exploring other materials that might work.
Another advantage of the PETE system is that by using it in solar concentrators, the amount of semiconductor material needed for a device is quite small.
"For each device, we are figuring something like a six-inch wafer of actual material is all that is needed," Melosh said. "So the material cost in this is not really an issue for us, unlike the way it is for large solar panels of silicon."
The cost of materials has been one of the limiting factors in the development of the solar power industry, so reducing the amount of investment capital needed to build a solar farm is a big advance.
"The PETE process could really give the feasibility of solar power a big boost," Melosh said. "Even if we don't achieve perfect efficiency, let's say we give a 10 percent boost to the efficiency of solar conversion, going from 20 percent efficiency to 30 percent, that is still a 50 percent increase overall."
And that is still a big enough increase that it could make solar energy competitive with oil.
Provided by Stanford University

Stanford Unveils Solar Tech That Harnesses Light and Heat

by Cameron Scott

Photo by Nick Melosh
We currently have two types of solar energy: energy generated from light, using silicon-based photovoltaic cells, and energy generated from heat, using solar concentrators and heat-conversion systems. What if we could collect both types of energy at once? Stanford researchers recently unveiled a new solar tech that can do exactly that — their PETE devices utilize a semiconducting material coated with cesium to boost efficiency levels up to 60 percent — three times that of existing systems.

Rooftop solar panels use silicon to convert light into electricity. But their efficiency declines rapidly at higher temperatures (like those needed to power heat-conversion systems). An either/or choice presents itself — but Stanford researchers found that a cesium coating allowed semiconducting materials to convert both light and heat into energy.
They dubbed the process PETE, for photon enhanced thermionic emission. Best of all, PETE devices could be cheaply and easily incorporated into existing solar collection systems. (Because the system hits peak efficiency at over 200 degrees Celsius, it’s not a good fit for rooftop arrays.) “The light would come in and hit our PETE device first,” explained lead researcher Nick Melosh. “We would take advantage of both the incident light and the heat that it produces, and then we would dump the waste heat to existing thermal conversion systems.”
PETE devices require only a small amount of semiconducting material, making them cheap. Melosh’s team also hopes to design devices that can easily be bolted on to existing solar collection systems, so that conversion would also be low-cost.
When used with the heat-conversion process, PETE devices could reach 60 percent efficiency. But even if they boost efficiency just to 30 percent, they will bring solar power down to the price point of oil. And that’s a good thing.

 

Solar Power Is Cheaper Than Nuclear for the First Time

by Cameron Scott

Here’s bright spot in the news of the day: energy from new solar installations has, for the first time, become cheaper than energy from new nuclear plants, according to a new Duke University study. Thanks to cost-saving technologies and economies of scale, price can no longer be an excuse to invest in nuclear power rather than solar.

In North Carolina, nuclear energy costs 16 cents per kilowatt hour (the energy required to run 10 100-watt light bulbs for an hour), whereas solar is now going for 14 cents per kWh — a rate that continues to fall. In regions with more annual sunlight, the price gap is almost certainly even more pronounced. The data also analyzed only conventional photovoltaic power, not the concentrating technologies of troughs and reflectors, which also bring costs down.
The study was developed in response to aggressive lobbying by the nuclear industry, which has tried to position itself as the most affordable way to reduce carbon emissions. The study factors in governmental subsidies for both power sources, but found that even if all subsidies were removed, solar power would still be cheaper within a decade.

NY’s Solar Thermal Plan Will Save State $175 Million Annually

by Brit Liggett

Sixty percent of the energy used in buildings in New York State goes to heat and hot water. This power heavy fact has been the the driving force behind a newly devised solar thermal energy plan that could eventually save New York State residents $175 million a year. Given that the last nation-wide energy bill was tossed out the window, individual states are now coming under pressure to come up with their own energy saving tactics. Thankfully, even in the face of ailing government support, New York’s new solar thermal plan is a shining example of how sustainable living remains a primary cause for most individuals. The state’s forward thinking plan will call for up to 1 million new solar thermal systems placed statewide, together able to provide a total of 2,000 MWth of solar powered heat by 2020.

Solar thermal energy harnesses the power of the sun to make hot water and feed steam heating systems. Much of the heat in older buildings comes from steam heat, so officials see solar thermal as a great alternative to feeding these systems. Relative to places like Germany where the solar thermal industry is booming — they install about 200,000 solar thermal heaters per year — the US has failed to see the value of such technology, often only perceiving it as useful in low-energy contexts such as for the heating of swimming pools. However, it is estimated that solar thermal heaters have the capacity to generate 50% of the hot water needed across the US.
Understanding the gains to be had with this innovative, yet simple and easily implemented technology, New York State will kick off a program which should provide incentives, educational opportunities, permitting improvements, research and development and installer training programs to encourage the installation of solar thermal systems. The program is expected to decrease energy for heating use by 6 million US gallons of oil, 9.5 million ft³ of natural gas and displace 320 GWh of electricity production per annum. With 70% of the systems coming from residential buildings and 30% of the systems from commercial buildings, the state estimates there will be a whopping $175 million in energy savings annually.

 

World’s First Molten Salt Solar Plant Produces Power at Night

by Philip Proefrock

Sicily has just announced the opening of the world’s first concentrated solar power (CSP) facility that uses molten salt as a heat collection medium. Since molten salt is able to reach very high temperatures (over 1000 degrees Fahrenheit) and can hold more heat than the synthetic oil used in other CSP plants, the plant is able to continue to produce electricity even after the sun has gone down.

While photovoltaic solar panels work by directly producing electricity from sunlight, CSP plants use mirrors to concentrate sunlight and produce high temperatures in order to drive a turbine to generate electricity. CSP plants have been in existence for many years, but the Archimede plant is the first instance of a facility that uses molten salt as the collection medium.
Heat from the molten salt is used to boil water and drive the turbines, just like other fossil fuel plants. CSP plants use the same kind of steam turbines as typical fossil fueled power plants. This makes it possible to supplement existing power plants with CSP or even to retrofit plants to change over to clean energy producing technology. Some existing CSP plants have used molten salt storage in order to extend their operation, but the collectors have relied on oil as the heat collection medium. This has necessitated two heat transfer systems (one for oil-to-molten-salt, and the other for molten-salt-to-steam) which increases the complexity and decreases the efficiency of the system. The salts used in the system are also environmentally benign, unlike the synthetic oils used in other CSP systems.

Since molten salts solidify at around 425 degrees F, the system needs to maintain sufficient heat to keep from seizing up during periods of reduced sunlight. The receiver tubes in the Archimede facility are designed to maximize energy collection and minimize emissions with a vacuum casing that enables the system to work at very high temperatures required with molten salts. By using the higher temperatures of molten salts, instead of oil, which has been used in other CSP plants until this point, the plant is able to maintain capacity well after the sun sets, allowing it to continue generating power through the night.
The Archimede plant has a capacity of 5 megawatts with a field of 30,000 square meters of mirrors and more than 3 miles of heat collecting piping for the molten salt. The cost for this initial plant was around 60 million Euros.

UAE Announces Plans for World’s Largest Solar Plant

by Bridgette Meinhold

It seems everyone is rolling out with plans for the world’s largest this or that and the UAE is joining the fray with a massive concentrated solar energy project called Shams 1. Masdar is teaming up with French oil company Total and Spanish solar company Abengoa Solar to build a 100 MW solar plant outside of Abu Dhabi in the United Arab Emirates (UAE). Compared to the monster Desertec project in Europe and North Africa, Shams 1 is a drop in the bucket, but will be up and running long before Desertec secures financing.

  

Shams 1, which is named for an Arabic word for sun, will be located 120 kilometers southwest of Abu Dhabi and will produce 100 MW of power. The plant is comprised of a solar field consisting of 768 parabolic trough collectors supplied by Abengoa Solar, plus a backup natural gas boiler to supply power when the sun is not on. The plant will displace approximately 175,000 tonnes of CO2 per year and directly contribute to the UAE’s goal of 7% renewable energy by 2020.
The new CSP plant will be jointly owned by Masdar (60%), Total (20%) and Abengoa Solar (20%). Construction is expected to commence in the fall of 2010 and should take approximately two years to complete, which means Shams 1 will be pumping out solar power by the end of 2012. Desertec, on the other hand, which has ambitious goals of 1 GW of CSP is likely to not be completed for at least another 15 years.

 

Greendix Develops First Leaf-Shaped Crystalline Silicon Solar Panels

by Ariel Schwartz

We all know that solar panels are at the forefront of green energy technology, but they aren’t the most aesthetically pleasing to look at. Aiming to solve that issue, Greendix, a custom solar panel supplier, has created what it claims is the first leaf-shaped PV crystalline silicon solar panel. And the company isn’t stopping there – they claim that their new technique could make PV panels in all different shapes and sizes.

The panel, which will be distributed by Sonelis Technologies, can be manufactured in a variety of colors. In a statement, Greendix president Joseph Lin noted, “One of the goals of my team was to take an existing technology, like solar panels, and revolutionize it so that it can seamlessly merge with our surroundings.”
Lin imagines that his leaf-shaped panels could one day populate entire solar forests. And who knows–since the leaves can be produced in multiple colors, those energy-generating forests might look a little psychedelic, too.

China Building “Biggest Solar Energy Production Base” in the World

by Bridgette Meinhold

Construction is in the works for what China is calling “The Biggest Solar Energy Production Base in the Whole World,” or more simply, Solar Valley. The base will be a clean energy technology hub that China hopes will rival Silicon Valley in California. The ambitious plans for the park were launched by Himin Solar Energy, whose headquarters is located at the Sun-Moon Mansion, which is currently the largest solar powered office building in the world. The planned development outside of Dezhou, China is expected to cost $740 million and accommodate 100 tenants.

 

 

Himin Solar Energy, started by Huang Ming, the ‘Sun King’ of China, is already the main tenant of Solar Valley and their large office building is completely powered by the sun. He has very ambitious goals about making Solar Valley a reality, and has already attracted about 100 companies, and spawned factories as well as a research center. The hope is that this clean energy epicenter will help propel China’s development of renewable energy technology and installation.
Solar Valley is located just outside of Dezhou, which is making some progress towards in building its reputation as a clean energy city. The city already requires that all new buildings be equipped with solar water heaters of the type made by Huang’s company, and last year they spent $10 million to install solar lighting along miles of road. Chiel Boonstra, a Dutch architect who heads up the International Solar Cities Congress, says that Dezhou “will be a new center of gravity for renewable technologies.” It’s just a shame that rural farmers are being relocated into block apartments in the city to make way for the grand new development.

http://www.inhabitat.com/2010/03/19/solar-city-tower-for-rio-olympics-giant-energy-generating-waterfall/

Solar City Tower for Rio Olympics is a Giant Energy Generating Waterfall

by Bridgette Meinhold, 03/19/10

This renewable energy generating tower located on the coast of Rio is one of the first buildings we’ve seen designed for the 2016 Rio Olympics, and boy, is it crazy! (In case you didn’t notice, it’s also a waterfall.) The Solar City Tower is designed by Zurich-based RAFAA Architecture & Design, and features a large solar system to generate power during the day and a pumped water storage system to generate power at night. RAFAA’s goal is that a symbolic tower such as this can serve as a starting point for a global green movement and help make the 2016 Olympic Games more sustainable.

The self-sustaining tower for the 2016 Olympic Games is designed to create renewable energy for use in the Olympic Village as well as the city of Rio. A large solar power plant generates energy during the day. Any excess power not used during the day is utilized to pump seawater into a storage tank within the tower. At night, the water is released to power turbines, which will provide nighttime power for the city. On special occasions water is pumped out to create a waterfall over the edges of the building, which RAFAA says will be, “a symbol for the forces of nature.” Info on the size of the solar and pumped water storage system is not available yet.
Access to the eco tower is gained through an urban plaza and amphitheater 60 meters above sea level, which can be used for social gatherings. On the ocean side of the 105 meter tower (behind the waterfall) is a cafeteria and shop. An elevator takes visitors up to the top floor where an observation deck offers 360 views of the ocean and city. At level 90.5, a bungee platform is available for adventurous visitors.