April 7, 2014 – Vol.19 No.1

Don't Stop Looking for New Green Tech.
by Bruce Mulliken, Green Energy News

New way to generate electricity gives hope that better, cheaper clean energy technologies are on the way.

For now, and into the foreseeable future, forget about any massive international effort to stem the tide of carbon emissions. With each new study the evidence of a man-made warming planet grows stronger, while the willingness for nations to band together to do anything about it grows weaker, it seems.

True, various governments have mandates, initiatives and programs to cut carbon emissions. But, the real focus is on what develops in the marketplace, in the private sector. Cutting emissions in a large way will come rapidly if and when highly profitable green technologies are launched globally. With that, new energy technologies need to be developed that are both pristine clean and cheaper than coal and oil and gas from the get-go, from day one, from the day the first product is launched. When dirt-cheap green energy is the next big thing carbon emissions will drop precipitously.

A tall order? Certainly. But don't think it's not possible. More than likely these technologies, these ideas, are probably already out there, but just not recognized.

But what are the new clean-cheap energy possibilities? ( I wish I knew!) However, generally speaking, here is what to look for:

So, I keep looking for fresh ideas. (As I have been for about 18 years of this publication.) Here's one that caught my eye when sent by a friend. It's from an article in the publication Nature Communications entitled "Radial-arrayed rotary electrification for high performance triboelectric generator"

(Triboelectric is defined as the production of electrostatic charges by friction. The authors call their triboelectric generator the TEG.)

While the production of static electric is nothing new, this little device uses two, flat, two-dimensional metal plates; one rotates, the other is static: The rotor and the stator. It's the clever design of the plates that makes the TEG work. The rotor looks like a flat turbine wheel. The stator consists of two electrodes that incorporate patterns that mimic the turbine-like shape of the rotor. The two stator electrodes are separated by a fine trench. As the rotor spins electricity is generated as the rotor passes over each electrode in the stator.

There are no wires or magnets in the design, just thin metals that can be really cheaply manufactured.

The authors offer this abstract:

"Harvesting mechanical energy is an important route in obtaining cost-effective, clean and sustainable electric energy. Here we report a two-dimensional planar-structured triboelectric generator on the basis of contact electrification. The radial arrays of micro-sized sectors on the contact surfaces enable a high output power of 1.5W (area power density of 19mWcm2) at an efficiency of 24%. The triboelectric generator can effectively harness various ambient motions, including light wind, tap water flow and normal body movement. Through a power management circuit, a triboelectric-generator-based power-supplying system can provide a constant direct-current source for sustainably driving and charging commercial electronics, immediately demonstrating the feasibility of the triboelectric generator as a practical power source. Given exceptional power density, extremely low cost and unique applicability resulting from distinctive mechanism and structure, the triboelectric generator can be applied not only to self-powered electronics but also possibly to power generation at a large scale."

The authors, who have built working prototypes of the TEG say this about power generation within the TEG: "The operation of the TEG relies on relative rotation between the rotator and the stator, in which a unique coupling between triboelectrification and electrostatic induction gives rise to alternating flow of electrons between electrodes."

They go on to say:

"From performance point of view, the TEG has substantially higher power density than the traditional generator in terms of both power-to-volume ratio and power-to-weight ratio due to much smaller volume and weight. The high power density imparts two major advantages to practical applications of the TEG. First, it is superior to the conventional generator as a small sized power source for self-powered electronics, for example, harvesting human motions for powering or charging portable/ wearable gadgets. In these applications, size and weight management become critical issues. Second, the significant power density makes the TEG potentially advantageous in large-scale power generation for stationary power plants, although the feasibility needs to be solidly validated with further investigations.

"From cost point of view, the TEG on the basis of surface charging effect only needs very small amount of materials. They are conventional thin-film insulating materials and metals of various kinds that are abundantly available. Besides, it has a simple structure and straightforward fabrication process. As a consequence, the TEG is extremely cost-effective, which is an unparalleled advantage compared with any other power generation techniques. The significantly low cost of the TEG is a key advantage for its potential widespread applications.

"Last but not the least, our unique 2-dimensional-planar generator owns distinctive applicability in a variety of circumstances. The usual generator has difficulty being made into a planar structure due to reasons such as poor properties of planar magnets, limited number of turns achievable with planar coils and restricted amplitude of displacement. In comparison, the TEG offers a straightforward and even sole solution to addressing rotation sliding between two surfaces. For example, it can be possibly integrated into a brake system in automotive and other applications where a brake rotor and brake pads have relative contact rotation."

Key, I think, to a clean energy future, is the willingness to take a hard look at conventional, time-tested ideas and be willing to toss aside technologies, even engineering principals, that are out of date. Maybe coils and magnets aren't the best and cheapest way to generate electricity. As shown above there are other ways to do it that might lead to a new wave of clean tech. It's what's needed.

 

"Radial-arrayed rotary electrification for high performance triboelectric generator"

 

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