Can hot air be the free fuel of the future?

You don't have to be a science major to know that heat rises: Just step into an attic on a hot summer day. But what you might not know is that this basic scientific reality could also help create clean energy for entire cities.

For centuries, architects have taken advantage of rising heat to help cool some structures. Solar chimneys allow the rising air to go out of the building, taking the heat with it.

                                                                     
Today, Australian entrepreneur Roger Davey wants to take advantage of that phenomenon -- with a twist.
"An Australian company says it can produce enough electricity for 100,000 homes by using the movement of hot air."

He wants to create, capture and control hot air to help power cities. He plans to build a huge solar updraft tower, 2,600 feet tall, in the Arizona desert. As the hot air moves into the tower, it would turn 32 turbines, spinning them fast enough to create mechanical energy, which generators convert to electricity.

His company, EnviroMission, says such a tower can create up to 200 megawatts of power, enough to power 100,000 homes. He says they don't intend to put coal or nuclear or alternative power out of business, but want to be a strong, no-carbon emission supplementary source.

"One of the most important things I think that differentiates this from anything else is its ability to produce power as and when required," said Davey, chief executive and executive director of EnviroMission, the company behind the solar updraft tower.

That sets it apart from solar (not available at night) and wind energy (not available on a calm day), which he referred to as "spasmodic."

He also touted its ability to produce power without the use of water to generate electricity. Coal-fired and nuclear plants use massive quantities of water, and solar panels need to be washed frequently to keep them working well.

On the drawing board

The EnviroMission tower is only a concept right now, but Davey says the technology has been proved by a smaller version that worked for seven years on the plains of Spain. It created 50 kilowatts of electricity per day, according to the German builders Schlaich, Bergermann and Partner.

But the 125-ton iron structure toppled in 1989 after its support cables broke, according to media reports. The company did not respond to CNN's request for comment.

A small tower began operation in China last year, according to the Xinhua news agency. The project -- funded by a Chinese company -- reportedly will cost $208 million and will be built in phases. The first section of the plant produces 200 kilowatts per day, Xinhua reported.

Right now, EnviroMission is the only publicly traded developer working on this technology, a company spokeswoman said.

Its model calls for a tower with no support wires and, unlike the other structures, it will be built from cement. The solar tower would be the second-tallest structure in the world, slightly shorter than Dubai's Burj Khalifa skyscraper.

EnviroMission says its tower will stand for 80 years, far longer than the average life for a field of solar panels, which some would see as an alternative with a smaller upfront cost.

Davey says the Arizona project will cost $750 million to build at its present size and scope (with further refinements the price could rise or fall 10% to 15%, he says).

EnviroMission has already raised "substantial capital" for its project, according to spokeswoman Kim Forte.

The company also recently presold the power that would be created at one of the Arizona facilities to the Southern California Public Power Authority, which comprises 12 utilities.

Mohammad Taslim, a professor of mechanical engineering at Northeastern University, says the two important concerns are: Will the plant produce as much energy as EnviroMission predicts and will it be economical and environmentally friendly?

"Fundamentally from an engineering standpoint it is sound," he said. "I believe that the question is not that this will not work at all. It might be the claim of 200 megawatts is not quite reachable at the peak."

Taslim initially said he thought the engineers should consider composite materials like carbon fiber. But, after a few back-of-the-envelope calculations, he concluded, "an 800-meter structure of composite materials cannot withstand its own weight and a much more complicated structure is required."

According to EnviroMission, the amount of carbon pollution created by the manufacture and shipment of the cement and other materials needed to build the facility will be offset after 2½ years of operation.

Spinning turbines create electricity

The technology works like this: Unlike normal solar photovoltaic panels that convert the sun's light into energy, the EnviroMission tower would create solar-thermal power, from both the sun and the wind.

Like a greenhouse, the sun heats up the air underneath a huge translucent, sloping canopy around the tower that is about as wide as a football field.

The air is heated to about 194 degrees Fahrenheit (90 degrees Celsius) and then it flows into the tower, spins the turbines and rises.

The higher the tower, the stronger the flow of air. The faster the turbines spin, the more electricity possible.

After sundown, the ground continues to release heat and more electricity would be generated.

The long road ahead

Davey says the hurdles to getting his solar tower built are a combination of political factors, environmental policies and the cheap cost of fossil fuels. He wanted to build this project in his home country of Australia, but he says the United States has a more acceptable political climate.

He also said that for the past 10 years EnviroMission has been doing its "due diligence" in designing a better solar tower plant to assure its potential private investors.

"We had to improve the technology from what it was from when the plant in Spain was built to what it is now -- commercially viable," he said.

The plant should take about two years to build and provide up to 1,500 construction jobs, he says. Then once the site is operating, a 30-person staff will operate the plant, providing maintenance to the canopy and turbines, as well as security and possible tours. Because air is free, operating costs will be minimal, he said.

The next step is determining the final capital costs, which will take a few months.

"And then you can work out whether the economics stack up," he said. "We've got to go to the bankers and ensure you can get it banked. We believe it will."

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Absolute power: how smart design is making servers greener

Servers are the power behind today’s always-on, hyper-connected world – but that power uses a lot of, well, power. The US Environmental Protection Agency predicted that by 2011, US servers would use some 2.5% of the entire country’s power supply; the real figure was lower (between 1.7% and 2.2%, according to Stanford University). Much of that difference is because of two things: better server design, and the rise of virtualisation.

                                                               
Virtualisation: doing more with less

As businesses grow, their IT demands grow too – and traditionally, meeting those demands has meant investing in more equipment. However, simply adding more servers isn’t always the best idea: not only do additional servers require additional power, but they also generate additional heat that will require additional cooling, which once again requires energy. With modern servers, virtualisation offers a much more efficient – and much more cost-effective – alternative.

Virtualisation enables a single server to do the work of several distinct machines, and it massively reduces organisations’ power requirements. As Jon Koomey of Stanford Unversity told Greenbiz.com, “running a single server for an application is a huge waste of capital. Systems have got more efficient with virtualisation.” Rather than have multiple servers running well below capacity, consolidating applications across fewer servers via virtualisation can have a dramatic effect on the bottom line – not just in terms of your power bills, but also in capital, maintenance, administration and support costs.

Virtualisation isn’t the only way to cut servers’ power requirements, though. Firms such as Dell have found that clever design can slash energy bills while boosting performance – a genuine win-win situation.

Heads you win, tails you win

By harnessing the latest generation of servers and focusing heavily on energy efficiency, the latest generation of Dell PowerEdge servers consume up to 25% less energy than previous generations while delivering improved performance. Dell reports performance increases of up to 3X the performance per watt compared to previous generations.

So how do they do it? Having your own Power and Thermal Lab, as Dell does in Austin, certainly helps: it’s where Dell works with partners to develop, validate and implement industry standard solutions for today’s energy efficiency challenges. Inside the lab, engineers can simulate various heating loads, model customer server loads and cooling capacity, and even use a smoke generator to study air circulation. Results are shared with Dell’s customers and the industry as a whole, and of course it’s used to inform future products.

Energy efficiency is a key priority for Dell, and its PowerEdge Energy Smart server range takes advantage of three key technologies: highly efficient processors, high efficiency system design and highly effective power management features.

Advanced processor technology makes an enormous difference, with dual- and quad-core low voltage processors designed to maximise performance while minimising power drain and heat generation. According to Intel, modern processor technology of the kind you’ll find in Intel’s Xeon range delivers incredible benefits: up to 40% more performance per watt than previous generations, delivering dramatic reductions in server energy costs


Save energy, save money

The processor is only part of the picture, though. Dell’s Energy Smart power supply units (PSUs) are engineered and right-sized to remove unnecessary overhead, achieving some of the highest efficiencies in the industry, and their reduced energy requirements help to achieve cooler internal temperatures – something that’s also helped by chassis designed for maximum ventilation and airflow.

Low-Flow fan technology constantly monitors the system’s thermal requirements, adjusting fan speeds accordingly, and Energy Smart systems design incorporates high-efficiency voltage regulators and highly effective power management tools that reduce system draw during periods of low utilisation and that offer features including power capping, power management policies, power scheduling and device disablement.

No detail is too small: for example, PowerEdge servers utilise smaller form factor hard disks, which use less energy than their larger siblings.

The results are dramatic. Compared to standard configurations, implementing PowerEdge Energy Smart servers means that for every four servers, customers can run a fifth at no additional energy cost; IT can fit four more 2U servers per rack without adjusting power specifications; and for every four racks, IT can add one complete rack at no additional energy cost. For smaller businesses, that’s a saving of hundreds of pounds per server per year, every year – and for large data centres, the annual savings can be in the high six figures.

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NASA'S WISE Mission Captured Black Hole's Wildly Flaring Jet

Astronomers using NASA's Wide-field Infrared Survey Explorer (WISE) captured rare data of a flaring black hole, revealing new details about these powerful objects and their blazing jets.

Scientists study jets to learn more about the extreme environments around black holes. Much has been learned about the material feeding black holes, called accretion disks, and the jets themselves through studies using X-rays, gamma rays and radio waves. But key measurements of the brightest part of the jets, located at their bases, have been difficult despite decades of work. WISE is offering a new window into this missing link through its infrared observations.

The black hole, called GX 339-4, had been observed previously. It lies more than 20000 light-years away from Earth near the center of our galaxy. It has a mass at least six times greater than the sun. Like other black holes, it is an ultra-dense collection of matter, with gravity that is so great even light cannot escape. In this case, the black hole is orbited by a companion star that feeds it. Most of the material from the companion star is pulled into the black hole, but some of it is blasted away as a jet flowing at nearly the speed of light.

Observing the jet's variability was possible because of images taken of the same patch of sky over time, a feature of NEOWISE, the asteroid-hunting portion of the WISE mission. WISE data enabled the team to zoom in on the very compact region around the base of the jet streaming from the black hole. The size of the region is equivalent to the width of a dime seen at the distance of our sun.

The results surprised the team, showing huge and erratic fluctuations in the jet activity on timescales ranging from 11 seconds to a few hours. The observations are like a dance of infrared colors and show the size of the jet's base varies. Its radius is approximately 15000 miles (24140 kilometers) with dramatic changes by as large as a factor of 10 or more.

The new data also allowed astronomers to make the best measurements yet of the black hole's magnetic field, which is 30000 times more powerful than the one generated by Earth at its surface. Such a strong field is required for accelerating and channeling the flow of matter into a narrow jet. The WISE data are bringing astronomers closer than ever to understanding how this exotic phenomenon works.

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