Saturday, December 10, 2011

Latest from: CleanTechnica

Latest from: CleanTechnica

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A Tougher and Lighter Wind Turbine Blade Design

Posted: 09 Dec 2011 05:11 PM PST

 

Wind turbine blade being transported by trailer.

A researcher from Case Western Reserve University has designed a stronger and lighter wind turbine blade design.

First, a little insight into the issue of blade strength:

As superior as large wind turbines are where cost and performance are concerned, the weight of their blades can cause problems. It is difficult to make such long (more than 200-feet in diameter) blades strong enough to bear their own weight, and especially at high speeds (explanation below).

There is a tendency of objects in general to resist a change of speed (velocity) – called inertia. It affects everything that moves. When the wind turns a wind turbine blade, the rest of the blades are forced to move with it since they share the same hub (the rotating part at the center of the turbine). However, the weight of the blades impedes that by holding them back.

It is almost as if there is a force pulling back on the blades, and this force actually bends the blade a little, but the problem with this is the blades are not really flexible — therefore, instead of bending, they break. This force (inertia) is the same one that you have to overcome when you first start running, and when you are trying to accelerate your vehicle.

This is why vehicles burn additional fuel to accelerate, and also to braking. Both bringing an object to a stop and moving it from a stop is a change of speed.

Weight adds to this inertia problem, which is why heavier objects (such as vehicles) are harder to stop and harder to get moving. Typical wind turbine blades are designed to withstand the stress that normal operation would cause, so they don’t break often.

This is why the same problem of inertia can be improved by making wind turbine blades both lighter, to reduce inertia itself, and stronger, to better withstand the inertia they are subjected to,.. and of course at a reasonable cost. Lighter wind turbine blades are easier to turn, and hence more efficient. So this is also important to their performance.

Back to the new blade design:

The researcher from Case Western Reserve University designed the 29-inch blades for a 400-watt turbine using polyurethane (a polymer) and reinforced it with carbon nanotubes.

“The idea behind all this is the need to develop stronger and lighter materials which will enable manufacturing of blades for larger rotors,” Loos said.

“Results of mechanical testing for the carbon nanotube reinforced polyurethane show that this material outperforms the currently used resins for wind blades applications,” said Ica Manas-Zloczower, professor of macromolecular science and engineering and associate dean in the Case School of Engineering.

“They will be used to emphasize the significant potential of carbon nanotube reinforced polyurethane systems for use in the next generation of wind turbine blades.”

Carbon nanotubes are still very expensive, but can be extremely lightweight and very strong compared to all-metal and composite materials.

h/t Science Daily | Photo Credit: sbwoodside

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“Greenhouse Gas” Technology Goes to Work for Low-Cost Solar Power System

Posted: 09 Dec 2011 04:36 PM PST

MIT uses greenhouse gas technology for low cost concentrated solar systemA team of researchers at the Massachusetts Institute of Technology has come up with a way to lower the cost of solar energy, by mimicking the same effect that enables greenhouse gases to trap heat in the Earth’s atmosphere. The new technology could eventually lead to powerful concentrated solar energy systems that don’t rely on the huge arrays of mirrors that are required in conventional systems.

Making More Solar Power without Mirrors

Instead of using mirrors, the MIT researchers fabricated a crystalline material arrayed with precisely spaced microscopic holes. Sunlight can enter the holes, but most of the radiation can’t find its way out by the same route. That’s because holes are configured in such a way that the rays must reflect back at precisely the right angle in order to escape. Think of a high-tech lobster trap of nanoscale proportions, and you’re on the right track. David L. Chandler of MIT News compares this approach to the greenhouse effect, in which radiation from the sun is admitted to the Earth’s atmosphere and is trapped there.

Many Routes to Low-Cost Solar Power

According to Chandler, the new material – called photonic crystal – could be manufactured using standard processes that are used to fabricate chips. That could give the new device a cost advantage over mirror-based technologies, which require precise optics to boost efficiency. The idea is that simplicity of manufacturing plays a key role in determining the installed cost of solar power, an approach that President Obama’s SunShot solar power initiative aims to encourage.

No Last Hurrah for Mirrors in Solar Energy

Despite the potential of the new technology, mirrors will most likely remain an important part of the low-cost solar toolkit. Another team at MIT, for example, is developing a low-cost concentrated solar system that positions mirrors on a hillside to focus sunlight downwards. That reduces the amount of pumps, piping and other complexities of conventional systems that aim

sunlight upwards, at a tower. As for optics, the aluminum giant Alcoa is working on concentrated solar systems using low-cost mirrors made of – what else – aluminum, with comes with the advantage that most of the installation could be easily recycled when it’s time for replacement.

Image: Greenhouse effect.  Some rights reserved by Global Jet.

Follow on Twitter: @TinaMCasey.

 

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EU Invades US for Energy Resource – Offshore Wind

Posted: 09 Dec 2011 02:21 PM PST

Not content with dominating the European off-shore renewable energy industry, European juggernauts of offshore wind have landed on the shores of Maine where they want to see if the US is good at making off-shore wind power too.

Norway’s Statoil, maker of the Hywind floating wind turbine in Europe (last year’s story: Oil Company Begins Wind Test of Off-Shore) is heading to the coast of Maine for a test of its Hywind floating turbine on these shores. Europe makes 99% of the offshore wind power in the world and is on track to build 141 GW more!!! over the next two decades. But Europe only has so much coastal water near population centers, suitable for off-shore wind. The USA however is… um, surrounded.

So while the US has busied itself digging up third world dictatorships for the energy to be gotten from under them, ton by laborious ton, Europe has moved on. Now it’s coming after a more permanent energy resource, in one of its former colonies.

Each floating Hywind unit from Statoil has a 2.3MW turbine on it made by Germany’s Siemens, the company that pretty much has a lock on offshore wind turbine production. The floating structure is a steel floater filled with ballast and it extends 100 m down (about 300 feet)  beneath the surface and is fastened to the seabed by three anchor wires.

The application is in response to a September 2010 request by the very progressive Maine Public Utilities Commission (MPUC) for proposals for deepwater offshore wind or tidal energy pilot demonstration projects. Maine was one of the first states to set a renewable energy standard and as a result is now blessed with a 55% renewable electricity supply  - if you count hydro, which supplies about 30% of that total – however it is also highly dependent on oil for heating.

We have covered Maine’s test of substituting stored wind power for heating oil (Maine Residents Get $6000 to Store Wind as Slow Heating) using Steffes thermal energy storage units in homes. Islands off Maine provide more than 100% of its needs from wind at times. Previous story: Incentives for Thermal Energy Storage for Night. These projects are the result of Maine’s excellent coastal offshore wind potential.

The University of Maine’s public/private partnership at its  Advanced Structures and Composites Center would like to see Maine generate 5GW of power by 2030 with floating turbines, and given Maine’s very progressive energy policy history: that is a pretty good chance. The DeepCWind Consortium at the U of Maine includes universities, nonprofits, and utilities, plus companies that specialise in marine construction, design and structures, composite materials to assist in corrosion-resistant material design and selection, and environmental law and analysis.

However, Statoil is also considering Scotland for the test. It’s up to the reorganized Bureau of Ocean Energy Management, which was broken out by this administration from the previous agency (the famously corrupt one that held cocaine parties with offshore oil driller applicants!) and then it will be up to FERC (Federal Energy Regulatory Commission) which fortunately has also changed leadership under this administration and is now run by the highly progressive Jon Wellinghoff, who gets it on renewables: see my Equal Pay for Negawatts and Megawatts Thanks to FERC.

But in the past, FERC has really dragged its feet on ocean energy development.

Which is why we don’t have any offshore wind industry and Europe does. But perhaps progressive Maine energy policy and the revamped BOEM and FERC can break through that now, with the help of Statoil the world leader in offshore wind development. Let’s hope so.

More from author Susan Kraemer 
//

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Solar for Schools? Not So Easy with Tax-based Solar Incentives

Posted: 09 Dec 2011 12:56 PM PST

You’re a city manager hoping to cut electricity costs at sewage treatment plant, a school administrator looking to power schools with solar, or a state park official needing an off-grid solar array for a remote ranger station.

But unlike any private home or business, you can’t get 50% off using the federal tax incentives for solar (a 30% tax credit and ~20% from accelerated depreciation).  That’s because the federal government’s energy policies all use the tax code, and your organization is tax exempt.

What about a public-private partnership?  The private entity puts up some money and gets the tax benefits, and the public entity only has to pay half.  It can work, if you’re lucky, although a good portion of those tax benefits (half, in recent years) pass through to that private entity for their return on investment, not changing the price of your solar array.

But the legal niceties also matter.  One common option is a lease, where the public entity leases the solar panels from the private one.  One big problem: the IRS doesn’t allow the private entity to collect the 30% tax credit if they lease to a public entity.

The cash grant program in lieu of the tax credit allowed leasing, but it expires in December.  Furthermore, it disallowed depreciation of the solar array, equivalent to 20% off.

Another clever arrangement is a power purchase agreement (PPA), where the third-party owns the solar array and simply sells the power to the school or city.  The third-party can claim both the tax credit and depreciation, but if you live in a state with a regulated utility market (and no retail competition), your utility might slap you with a lawsuit for violating their right to exclusive retail service.

The following chart illustrates the financial challenge for public entities created by using the tax code to support solar.

solar schools

Even with a lot of legal creativity, the public sector is often stymied in accessing both federal solar incentives.  The result is that private sector solar projects always get a lower cost of solar, because the public sector can only access federal incentives through (costly) partnerships with third parties.

Using the tax code for solar (instead of cash grants, production-based incentives, or CLEAN Contracts) is bad for the solar business, bad for taxpayers and bad for ratepayers.  It’s time to change course, and let the public sector go solar, too.

Related posts:

  1. Group Purchase Gets Residential Solar to Grid Parity in Los Angeles
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  3. America and Germany Getting Their Clean Energy Just Desserts


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