This article was on the Science Daily website last week. It appears that extensive educating of children is necessary if mass transportation, smaller vehicles, and greener transport options are to be more popular in the future. It was written in England with information gathered there, but there’s no doubt that it applies worldwide.

Source: http://www.sciencedaily.com/releases/2008/12/081204074658.htm

Young People Choose Cars Above Greener Transport Options

ScienceDaily (Dec. 5, 2008) — Young people find the prospect of driving cars more attractive than other modes of travel that are kinder to the environment, according to research conducted by a researcher at the University of the West of England.

Dr Tilly Line has just completed a PhD entitled ‘The attitudes of young people towards transport in the context of climate change.’ Dr Line’s work examined how young people are influenced by knowledge about climate change when it comes to making choices about how they will travel when they become adults. The study concentrated on the views of young people aged between 11 and 18 years and the findings found an overwhelming desire by young people to drive.

Dr Line explains, “Specific attention was give to how climate change considerations affect these intentions. Overall it was found that the participants have a general understanding of the link between transport and climate change, but when it comes to their attitudes towards different modes, they place higher value on identity, self-image, and social recognition than the environment. It is this that explains their positive attitudes towards the car and driving in favour of alternative modes. For example, the participants pointed to learning to drive as “a mile-stone in teenage life” - something that everyone does at seventeen. They also pointed to the car as a symbol of social status and the importance of their role as a driver in their friendship groups.”

Comments from those who took part include:

• “Limousines, they’re like a really special thing for like if you’re posh or you have lots of money. That’s why I want to have one of them.” (11 yr-old female participant)
• “Me and my friends share lifts to school in the mornings. Now our friends, all of our group have actually passed, we take it in turns to drive places…we share everything.” (18 yr-old female participant)

Dr Line continues, “Although it is recognised that transport policy makers are likely to require an understanding of the degree to which these values and attitudes are universally held among young people, it is suggested that policy aimed at reducing the public’s reliance on the car and increasing their use of alternative modes, should recognise such values, particularly in relation to soft policy measures (including marketing activities) targeting the socio-psychological motivations for travel choice. For example, one answer may be to promote cycling as a signal of success and ‘being cool’, rather than promoting the environmental benefits of this behaviour.”

“The importance of climate change shouldn’t be forgotten however. It isn’t the case that young people dismiss this issue, but more that they feel powerless to make a difference. I found that the young people think of climate change as being something that will not be felt until far off in the future and that there is little that they can do as individuals.”

• “There are little things you can do, but nothing that will change the world, because individually we’re only little people.” (11 yr-old female participant)
• “I’d like to change it. But I know I wouldn’t be able to, just me. If I really tried I know that I would just be wasting my life trying to do one thing I knew I couldn’t change.” (11 yr-old female participant)
• The participants also suggested that although they receive information about what climate change is, they lack information about what they can do to tackle it:
• “You don’t really get told what to do. …Instead of just saying ‘we’re polluting the world’, tell us what we can do about it.” (11 yr-old male participant)

Dr Line concludes, “On a positive note, I found that a number of the young people welcomed the idea that hard policy ideas leading to enforced travel behaviour away from reliance on cars would lead to a change in behaviour. But that this would only be possible if walking, cycling and public transport was easily accessible and reliable. This was even the case amongst those participants already driving and it seemed to stem from the belief that such action would empower more people to attempt to tackle climate change through changes in their travel behaviour as everyone would have to behave in the same way.”

• “I think some people may want to help the environment but they don’t do anything about it but then again if they were forced to then they’d have to. …I mean eventually it’s going to happen anyway. It’s going to come to a point in time where there’s going to be a ban on cars or something …there’s just going to be no feasible way they can have all the cars on the road.” (18 yr-old male participant)

Source: http://www.sciencedaily.com/releases/2008/12/081204074658.htm

This item was on the Gizmag blog over the holiday. I am impressed with this concept. It seems to me to be a rather elegant idea to harness wave energy. It uses wave energy to pump seawater to a reservoir where it can be dumped back into the ocean through a turbine to produce electricity or hydraulic pressure or whatever other energy is needed. This offers the capability to “store” energy in the reservoir during low demand times and then releasing it during high demand times, much like the pumped storage projects at places like Bath County, Virginia or Niagara Falls, New York. The pump itself is a simple concept with a minimum of moving parts. (only a double acting piston and some check valves) I can visualize these devices being assembled completely on land and then towed to their permanent site, where the anchor at the bottom could be pumped full of concrete and the whole assembly would then float to an upright position.  Lightweight hoses could then connect each one (As I’m sure it would be more efficient to produce many small ones instead of one or so large ones.) through a manifold to a large pipe to a reservoir, preferably on land, I would assume.  Their would have to be some careful specification of materials, as salty sea water will corrode many common substances.  This looks like a good project a student could replicate on a small scale with help from our AFV Lab.

Source: http://www.gizmag.com/searaser-hydro-power-system/10458/

Making waves work: the Searaser hydro-power system

November 27, 2008 Like the VIVACE system recently covered on Gizmag, SEARASER is a new approach to utilizing hydro-power as a renewable energy source. The idea works on the conventional principle of using water pressure to drive turbines but achieves this in a unique way. It consists of a tethered wave energy converter which uses the rolling motion of waves to pump water to higher ground on-shore from where it can then be stored and used to create electricity on demand.

Source: http://www.gizmag.com/searaser-hydro-power-system/10458/

This article was on the Gas2.0 blog this morning.  It seems like a rather ingenious idea that makes a lot of sense.  The two parabolic mirrors allow the heavy metal and water generator portion to be down at the base of the device instead of suspended up in the air at the focal point of the first mirror.  I’ve often pondered ways of using a thermocouple based device to generate electricity and couldn’t arrive at a way to do it, but these researchers seem to have found a way.  This looks like a concept that is worth watching, and maybe a good candidate for an AFV Lab project in the future.  Go to http://gas2.org/2008/11/09/simple-device-invented-in-1833-may-lead-to-cheap-hydrogen/ to see the original article.

Simple Device Invented in 1833 May Lead to Cheap Hydrogen

Written by Nick Chambers

Published on November 9th, 2008

Posted in Hydrogen, Science

A modern team of Italian researchers has uncovered a device invented by fellow Italian G.D. Botto in 1833 that can be used to generate hydrogen with inexpensive, everyday parts. By reflecting sunlight from two parabolic mirrors onto a hollow tube wrapped in metal and filled with water, the device generates enough electricity to produce hydrogen through electrolysis. Theoretically, the device is so simple that anybody could build it in their garage.

In the original Botto device, alternating links of platinum and iron were connected in a chain that was then wrapped around a wooden rod. By heating one side of the rod with a flame, Botto was able to generate an electric current in the chain through thermocoupling of the two metals.

Botto’s original intent was to simply show that he could produce electricity using a thermocouple of two metals. Making hydrogen bubbles in water through electrolysis was his way of visually confirming an electric current was present. But, after uncovering the original Botto work, the modern Italian team realized the device had a different kind of potential in today’s energy-dependent world: a cheap way to make hydrogen without advanced manufacturing techniques using off-the-shelf components.

With some modern thinking, the Italian team was able to modify Botto’s device in rather ingenious ways. Firstly, they replaced the flame that Botto used to produce heat with parabolic mirrors to concentrate the sun’s rays on the tube. Secondly, they replaced the rather expensive platinum metal with copper. And thirdly, in order to create a greater temperature difference between the heated side of the tube and the cool side of the tube (greater temperature difference equals larger current), they ran water through the center of it.

The researchers estimate that, although the power output for their experimental device is small (only about 20 mW), it could generate enough current to produce hydrogen gas through electrolysis of water. Given that the device is scalable, I’m guessing it would simply be a matter of daisy chaining enough of them together to generate the required amount of hydrogen.

The researchers also suggest that rather than using a thermocouple of two metals, it would be more efficient to use a thermoelectric semiconductor to obtain a much higher power output. I’m just waiting for them to release a design on the internet so that we can all start experimenting with hydrogen production.

Image Credit: De Luca, R.; Ganci, S.; and Zozzaro, P. “Revisiting an idea of G D Botto: a solar thermoelectric generator.” Eur. J. Phys. 29 (2008) 1295-1300.
Source: PhysOrg.com

Source: http://gas2.org/2008/11/09/simple-device-invented-in-1833-may-lead-to-cheap-hydrogen/

This article was on the Science Daily Website this morning. If this coating can be produced economically, it shows promise to make solar electricity generation much more attractive. Not only does it make solar cells more efficient, improving their efficiency from absorbing “…67.4 percent of sunlight shone upon it…” at present to absorbing “…96.21 percent of sunlight shone upon it…” after application of the coating, it also makes solar cells equally efficient regardless of the angle of the sun’s rays.  From the article:   “…his antireflective coating absorbs sunlight evenly and equally from all angles. This means that a stationary solar panel treated with the coating would absorb 96.21 percent of sunlight no matter the position of the sun in the sky….” If this is indeed true (The article doesn’t mention any independent verifications of its claims. I hope this isn’t just “grant fishing.”) then solar panels can be installed on roofs in the same plane as the roof. This avoids installing the extra superstructure needed to align panels to the optimum angle to take best advantage of the sun and the attendant unsightliness of such structures.  Go to http://www.sciencedaily.com/releases/2008/11/081103130924.htm to read all the details.

Solar Power Game-changer: ‘Near Perfect’ Absorption Of Sunlight, From All Angles

A new antireflective coating developed by researchers at Rensselaer could help to overcome two major hurdles blocking the progress and wider use of solar power. The nanoengineered coating, pictured here, boosts the amount of sunlight captured by solar panels and allows those panels to absorb the entire spectrum of sunlight from any angle, regardless of the sun’s position in the sky. (Credit: Rensselaer/Shawn Lin)

ScienceDaily (Nov. 4, 2008) — Researchers at Rensselaer Polytechnic Institute have discovered and demonstrated a new method for overcoming two major hurdles facing solar energy. By developing a new antireflective coating that boosts the amount of sunlight captured by solar panels and allows those panels to absorb the entire solar spectrum from nearly any angle, the research team has moved academia and industry closer to realizing high-efficiency, cost-effective solar power.

“To get maximum efficiency when converting solar power into electricity, you want a solar panel that can absorb nearly every single photon of light, regardless of the sun’s position in the sky,” said Shawn-Yu Lin, professor of physics at Rensselaer and a member of the university’s Future Chips Constellation, who led the research project.  “Our new antireflective coating makes this possible.”

An untreated silicon solar cell only absorbs 67.4 percent of sunlight shone upon it — meaning that nearly one-third of that sunlight is reflected away and thus unharvestable. From an economic and efficiency perspective, this unharvested light is wasted potential and a major barrier hampering the proliferation and widespread adoption of solar power.

After a silicon surface was treated with Lin’s new nanoengineered reflective coating, however, the material absorbed 96.21 percent of sunlight shone upon it — meaning that only 3.79 percent of the sunlight was reflected and unharvested. This huge gain in absorption was consistent across the entire spectrum of sunlight, from UV to visible light and infrared, and moves solar power a significant step forward toward economic viability.

Lin’s new coating also successfully tackles the tricky challenge of angles.

Most surfaces and coatings are designed to absorb light — i.e., be antireflective — and transmit light — i.e., allow the light to pass through it — from a specific range of angles. Eyeglass lenses, for example, will absorb and transmit quite a bit of light from a light source directly in front of them, but those same lenses would absorb and transmit considerably less light if the light source were off to the side or on the wearer’s periphery.

This same is true of conventional solar panels, which is why some industrial solar arrays are mechanized to slowly move throughout the day so their panels are perfectly aligned with the sun’s position in the sky. Without this automated movement, the panels would not be optimally positioned and would therefore absorb less sunlight. The tradeoff for this increased efficiency, however, is the energy needed to power the automation system, the cost of upkeeping this system, and the possibility of errors or misalignment.

Lin’s discovery could antiquate these automated solar arrays, as his antireflective coating absorbs sunlight evenly and equally from all angles. This means that a stationary solar panel treated with the coating would absorb 96.21 percent of sunlight no matter the position of the sun in the sky. So along with significantly better absorption of sunlight, Lin’s discovery could also enable a new generation of stationary, more cost-efficient solar arrays….

Source: http://www.sciencedaily.com/releases/2008/11/081103130924.htm

This item was in a Forbes.com newsletter I get. It reports on a fascinating new idea in solar electric power generation. It’s one of those classically “elegant” solutions that seem so simple and obvious that one wanders why no one thought of it before. Go to http://www.forbes.com/technology/forbes/2008/1117/058.html?partner=technology_newsletter to read the full article. They simply make huge balloons that have the form of segments of rotated parabolas, with a thin reflective coating on one half and a clear film on the other half. At the focal point of the reflective rotated parabola, which is inside the balloon, they situate a solar cell array. For a video that explains the concept much better than I can, go to http://www.youtube.com/watch?v=kROgE4Jdm-k . This looks like something we could duplicate and study in the AFV Lab.

Solar Bubbles

Kerry A. Dolan 10.29.08, 6:00 PM ET
Forbes Magazine dated November 17, 2008

Here’s an audacious bet: Cheap plastic balloons with solar cells inside can solve the world’s energy problem.

Behind a warehouse workshop in Livermore, Calif., an 8-foot shiny plastic balloon soaks up the abundant late September sun. Its shape reflects so much heat to its middle that you can’t leave your hand on it or you’ll burn. Insert a round plate covered with solar cells into the balloon and you may have the next idea in renewable power.

Eric Cummings, the brainy scientist who dreamed up the balloon idea, dismisses flat solar panels as expensive to install and difficult to deploy. The curvature of his balloon concentrates more sunlight onto fewer photovoltaic cells. He envisions vast farms of his 1-kilowatt balloons strung on wires and producing gigawatts of power.

Cummings has no deals yet with a utility, but his company, Cool Earth Solar, raised $21 million from Quercus Trust, a Los Angeles private equity firm, and other investors to build a 1.5 megawatt installation in California’s Central Valley. Construction of a test project in a field of brown weeds across the street from its offices is just beginning. “This is scalable in a way that dwarfs other options,” he boasts. “The goal is to be the 100% solution” to the energy crisis.

Cool Earth Chief Executive Robert Lamkin, who previously oversaw the development and construction of power plants at Calpine and managed plants at Mirant, says rather boldly that next year the company will have its costs down to $1 per watt, installed—at which point it can compete with natural gas and beat other kinds of solar technologies. Typical photovoltaic panels on rooftops cost up to $8 per watt installed. Solar thermal power, which concentrates heat to make steam, is aiming for $4 per watt. (These costs are all in terms of peak watts. Nights and clouds included, solar’s average cost per watt is four times as much.)

Whether solar balloons are viable has yet to be proved. “It’s definitely a nice idea, but this doesn’t appear to be a game changer,” says Daniel Kammen, a professor in the Energy & Resources Group at UC, Berkeley. Kammen says far bigger balloons up in the jet streamwould generate more electricity. Says Christopher Porter of Photon Consulting in Boston, “Relative to other solar, we’re not particularly excited about concentrated photovoltaics as a broad technology group.”

Cummings, 41, is undeterred. He has a doctorate in aeronautics and quantum chemistry from the California Institute of Technology—and a record of solving challenging problems. At the Department of Energy’s Sandia National Laboratories in Livermore, Cummings solved a 150-year-old electromechanical design problem in three months, pioneering a method to quickly and simply separate molecules.

Concentrating the reflected light into a receiver produces 300 to 400 times as much electricity out of each solar cell as a system without a concentrator, the company claims. A water-cooled jacket on the back side of the receiver keeps it from overheating. The balloon can add or bleed air to maintain its shape.

Cool Earth’s balloons can last five years but are so cheap it plans to replace them once a year. Or more frequently. It has yet to test against BB guns.

I came across this item on the About.com Hybrid Cars & Alt Fuel blog this morning.  It includes a table that lists the energy equivalents of most popular transportation energy sources. It may be of use in evaluating the MPGe (Miles Per Gallon Equivalent) of alternative fuels and thus facilitating an “apples to apples” comparison of alternative fuels.  Go to http://alternativefuels.about.com/od/resources/a/gge.htm?nl=1 to read the details.

Energy Equivalency Calculation

Using fuel energy equivalents provides the user with a comparison tool for gauging various fuels against a known constant that has relative meaning. A common method of measurement is the Gasoline Gallon Equivalent. The chart at the bottom of this page arrives at the equivalent measurement by comparing the BTU content per unit of each fuel type and then calculating the ratio.

What’s a BTU?

As a basis for determining energy content of a fuel, it is helpful to understand exactly what a BTU (British Thermal Unit) is. Its scientific definition goes something like this: British Thermal Unit - The amount of heat (energy) required to raise the temperature of 1 pound of water by 1 degree Fahrenheit.

Think of it this way: it’s basically a standard. Just as PSI (pounds per square inch) is a standard for measuring pressure, so too is a BTU a standard for measuring energy content.
See GGE conversion chart below

Source: http://alternativefuels.about.com/od/resources/a/gge.htm?nl=1

This article was on the RenewableEnergyWorld blog this morning. It makes some interesting points. For instance, it proposes the idea that, in the world of Sustainability, bigger is not necessarily better and that there is something to be said for local, smaller sustainable energy development projects. This brings to my mind several local entities that could benefit from such decentralization. The first to come to mind is the ongoing biodiesel project Ian Heatwole is spearheading. I don’t know what his business model is, but, in accordance with this article I can see it as possibly involving local farmers “trading” their soybeans for diesel fuel to run their equipment. This would result in substantial cost savings and reduction in energy consumption from transporting diesel fuel, be it petroleum diesel or biodiesel, over great distances from huge refineries.  Another local entity that could implement the ideas in this article is the Shenandoah Valley Electric Cooperative (SVEC), a local consumer owned supplier of electricity.  “Chartered on June 26, 1936, the Cooperative today serves over 38,000 residential, agricultural, commercial and industrial accounts in the Virginia counties of Augusta, Rockingham and Shenandoah, and Hardy County, West Virginia.” according to its website. Perhaps the SVEC could prevail upon its farm members to install windmills on their farms or solar panels on poultry houses in return for favorable electricity rates. Food for thought, don’t you think? I’m sure there are other instances that may benefit from this decentralized concept of energy production and use. Go to http://www.renewableenergyworld.com/rea/news/reinsider/story?id=53804 to read the full article.

Rural Power: The Key to Sustainability

The next twenty years could see up to US $1 trillion of investment in renewable energy in rural areas. Wind and solar power will be harnessed; and non-food crops will provide the fuel for a new generation of biofuels. But will rural areas reap the benefits of this massive investment or will communities merely observe the remaking of rural economies?

Source: http://www.renewableenergyworld.com/rea/news/reinsider/story?id=53804

I ran across this item in Science Daily this morning. It is an interesting concept. Is there technology to make a circuit that is both charger and inverter, i.e., can use line voltage to charge batteries and then take battery voltage and invert it back to line voltage? I don’t know of any. If not, this concept would be workable only by adding an inverter circuit in parallel with the charger circuit, with attendant control mechanisms, which would add considerably to the purchase price of a PHEV. Go to http://www.sciencedaily.com/releases/2008/10/081002172140.htm to read the full article

Scientists Explore Putting Electric Cars On A Two-way Power Street

ScienceDaily (Oct. 12, 2008) — Think of it as the end of cars’ slacker days: No more sitting idle for hours in parking lots or garages racking up payments, but instead earning their keep by providing power to the electricity grid.

Scientists at the University of Michigan, using a $2 million grant from the National Science Foundation (NSF), are exploring plug-in hybrid electric vehicles (PHEV) that not only use grid electricity to meet their power needs, but return it to the grid, earning money for the owner.

“Cars sit most of the time,” said Jeff Stein, a professor in the Department of Mechanical Engineering. “What if it could work for you while it sits there? If you could use a car for something more than just getting to work or going on a family vacation, it would be a whole different way to think about a vehicle, and a whole different way to think about the power grid, too.”

The concept, called vehicle-to-grid (V2G) integration, is part of a larger effort to embrace large-scale changes that are needed to improve the sustainability and resilience of the transportation and electric power infrastructures. If V2G integration succeeds, it will enable the grid to utilize PHEV batteries for storing excess renewable energy from wind and the sun, releasing this energy to grid customers when needed, such as during peak hours.

This will lead to more sustainable transportation and grid infrastructures, and will also increase the resilience of these infrastructures to sharp changes in energy costs, supply, or demand.

The NSF’s Emerging Frontiers in Research and Innovation program created a topic for a 2007-2008 call for proposals on resilient and sustainable infrastructures. This topic argues that the nation’s infrastructures over the past century have evolved largely independently but new technologies have emerged that coupled some of these infrastructures. This has created a need for fundamental tools to design and develop these new technologies and to evolve these coupled infrastructures.

Stein and others see the PHEV as a perfect example of such a new technology that in this case is coupling the transportation and power grid infrastructures.

V2G is an opportunity to look at vehicles beyond shaving miles per gallon. A team of experts in mechanical and power systems engineering, economics, and industrial ecology will examine every aspect of a PHEV and how it interacts with the electrical grid.

If PHEVs, which are anticipated to be on the market in 2010, fulfill their promise, millions could be on the road in the decades to come. This potentially will provide unprecedented shared battery storage to the grid and transportation infrastructures, thereby allowing these infrastructures to store renewable energy when available and use it when needed.

Aging electric plants are good at generating power, Stein said, but they face challenges in storing it, and lack ways to buffer against either big surges in demands, or interruptions in supply. Massive storage systems can be costly and problematic.

But, Stein said, think of all the “distributed” storage packed into millions of PHEVs on the road. He and his colleagues envision a world where the electric cars could double as mobile holding tanks for electricity, ready to serve in their down time.

“If we had lots of PHEVs all plugged into the grid, then what seems like an insignificant amount of energy storage becomes a large energy storage,” he said….

Source: http://www.sciencedaily.com/releases/2008/10/081002172140.htm

I came across this interesting article in Renewable Energy World.com’s blog this morning. The concept is new to me, and I’m fascinated by it. It seems to be quite an elegant concept.  It’s not terribly economic at this point in time, as the article itself says: Estimates for the cost of electricity produced range from €0.05 per kilowatt-hour (kWh) up to €0.25 [US $0.07 to 0.34 per kWh], depending on the cost of land and the financing scenario. However, it is carbon neutral and there is very little maintenance after the initial investment, (keeping the membrane repaired and the turbine/generator serviced and maintained.)  I wasn’t very far into reading the article before I wondered:  Why wouldn’t this work better using some portion of the top half of one of Buckminster Fuller’s Geodesic Domes?  Go to http://www.renewableenergyworld.com/rea/news/story?id=53742 to read more about this concept. The article is too long to include all of it here.

Solar Updraft Towers: Variations and Research
by Tom Bosschaert
Rotterdam, the Netherlands [RenewableEnergyWorld.com]

Aerial Photo of Solar Updraft Tower

The idea of using solar radiation to generate air convection that can subsequently be converted to an energy source has been around since the start of the 20th century, when a Spanish Colonel called Isidoro Cabanyes proposed it in a scientific magazine. Solar Updraft towers, also called solar wind or solar chimney plants, provide a very simple method for renewable electricity generation, with a constant and reliable output. Other renewable energy sources such as wind turbines and solar arrays suffer from high diurnal and seasonal fluctuations, or unpredictable patterns of output.

Due to the large initial investment required, unfamiliarity with the system and the solar updraft tower’s relatively low capture efficiency, only one prototype was ever built, in the 1980’s in Spain. This prototype however, performed above and beyond expectations, and continued to operate for almost 7 years after its designed life span of 3.

The solar updraft tower has been left on the shelf due to its perceived low efficiency, which is to a large degree undeserved. Most studies on this elegant and simple renewable energy producer consider the land occupied by the tower and its collector as one of the largest resource inputs required for this process. However, Except Architecture & Consultancy is investigating the possibility of more creative applications of the system, which would combine the tower with other land uses.

The Classic Solar Updraft Tower Scenario

The small experimental solar updraft tower plant, built in Manzanares, Spain in 1982 by Schlaich Bergermann, can be considered the classic example of the system. The design calls for a large, unused plot of land to house a collector between 500 m and 10 km in diameter, with a centrally located chimney ranging from 100 m to 1 km in height. The collector is a transparent membrane suspended several meters off the ground, which can be made of glass or a strong transparent polymer. (See pilot plant image left, as well as lead image, above.)

Sunlight penetrates this membrane, and the solar radiation is converted to heat upon hitting the ground. The air underneath the membrane quickly increases in temperature due to the greenhouse effect and flows towards the chimney, which, through the stack effect, becomes the lowest point of pressure in the system. This continuous airflow spins a turbine located at the base of the chimney. The nighttime difference in temperature between the ground and the air allows this effect to continue. Thermal storage devices can be used to smooth out the differences in intensity between night and day temperature differentials. As with other solar technologies, a higher latitude placement translates into a lower energy output. (See Figure 1, below.)

Schematic of Solar Updraft Tower

Figure 1: Classic Solar Updraft Tower Diagram…

To read the rest of the article, go to: http://www.renewableenergyworld.com/rea/news/story?id=53742