A Tensegrity Solar Collector

Timothy Wilken

As a synergic scientist I am always delighted when I discover others making use of tensegrity.

What is a tensegrity?

Tensegrity is the pattern that results when push and pull have a win-win relationship with each other. The pull is continuous and the push is discontinuous. The continuous pull is balanced by the discontinuous push producing an integrity of tension–compression.

Push and pull seem so common and ordinary in our experience of life that we humans think little of these forces. Most of us assume they are simple opposites. In and out. Back and forth. Force directed in one direction or its opposite.


Buckminster Fuller, who coined the term tensegrity, explained that these fundamental phenomena, push and pull, are not opposites, but rather compliments that can always be found together. He further explained that push is divergent while pull is convergent.Imagine pushing a yellow ping pong ball on a smooth table with the point of a sharp pencil. The ball would always roll away from the direction of the push, first rolling one way then the other. Push is divergent.

Now imagine the difference, if you attach a string to the ping pong ball with tape, and pull it toward you. No matter how other forces might influence the ball to roll away from you, the string would always bring it to you more and more directly. Pull is convergent.

Another example from common experience occurs when we are pulling a trailer with our car. When I am driving uphill, I am pulling against gravity. The trailer converges nicely behind my car. If the trailer begins to sway, I can dampen it by increasing pull– simply increasing my acceleration. Now if I am driving downhill, the trailer may begin to push. This produces a strong side to side force – divergence. My trailer will begin to sway from side to side. Push is divergent. When the trailer begins to push us, experts advise us to accelerate our car in order to re-establish pull. Pull is convergent. The trailer will straighten out and we can congratulate ourselves for being good drivers. These then are the two always co-existing fundamentals of Universe–Push and Pull–Compression and Tension–Repulsion and Attraction.

A more common example of a tensegrity is a child’s balloon. When we examine an inflated balloon as a system, we find that the rubber skin of the balloon continuously pulls while the individual molecules of air are discontinuously pushing against the inside of the balloon keeping it inflated. All external forces striking the external surface are immediately and continuously distributed over the entire system. This makes the balloon very strong. We all know how hard it is to break a good balloon with a blunt blow.

Molecules of air discontinuously pushing against the continuously pulling rubber skin of the balloon.Tensegrity is a balance of continuous pull and discontinuous push.

The automobile tire is one of the strongest most durable inventions in the history of humankind. And yet few of us are even aware that it is a tensegrity.

It is the power of tensegrity in each tire that protects us from failure and blowout despite high speeds and long miles.

A tensegrity then is any balanced system composed of two elements – a continuous pull balanced by discontinuous push. When these two forces are in balance a stabilized system results that is maximally strong. The larger the system the stronger the system.

Most of humanity knows of Fuller’s discovery of the Geodesic Dome, but few realize that geodesic domes are themselves tensegrities.

What does Dymaxion mean?

Synergic scientist Buckminster Fuller coined another term to represent the concept of “least action”—the concept of “doing the most with the least”—the concept of achieving “maximum efficiency.”

Today, I discovered a small start-up company called Cool Earth that is using the power of tensegrity to help create a new dymaxion technology to produce abundant clean and safe energy. Electrical power is the most convenient form of energy for modern living. Today, most electricity is created by burning fossil fuels. As we know fossil fuels are no longer abundant and they have never been safe. The following is from the Cool Earth website.

How much electricity does the world use?
As reported in the 2008 EIA International Energy Outlook Report, electric power plants produced 17,320 terawatt-hours (TWh) in 2005. In 2030, the world is projected to need about 33,264 TWh—nearly double the amount of 2005.

How much energy does the Sun provide?

The amount of sunlight that hits the Earth’s surface in one hour is enough to power the entire world for a year.

How many solar power plants would the U.S. need to meet its electric needs?

One solar power plant, using Cool Earth’s technology, covering 150 miles by 150 miles, would generate enough power to meet all the electrical needs of the United States through 2030.

Eric Cummings

A Tensegrity Solar Collector

Our technology, which is the basis for our power plants, is “reshaping solar energy” in a very literal way: Most of today’s solar energy systems take the form of flat panels or boxes-with-lenses and require large amounts of heavy, expensive materials. Our inflated solar concentrators, on the other hand, are shaped like balloons and are primarily made of inexpensive and free materials. This design approach radically reduces material requirements as well as our plant deployment costs and time.


Solar Concentrators Focus the Sun…

Our inflated, balloon-shaped concentrators are key to Cool Earth’s innovative design. Each 8-foot-diameter concentrator is made of plastic film—the same kind of plastic film used to bag potato chips, pretzels, and so on—with a transparent upper hemisphere and a reflective lower hemisphere. When inflated with air, the concentrator naturally forms a shape that focuses or concentrates sunlight onto a PV cell placed at the focal point. This means we need fewer cells to produce a lot more electricity. In fact, a single cell in our concentrator generates about 300 to 400 times the electricity of a cell without a concentrator.

The inflated structure is naturally strong—strong enough to support a person’s weight—and aerodynamically stable, able to withstand winds of 125 miles per hour. Finally, the transparent upper surface protects the PV cell and mirrored surface from the environment, including rain and snow, as well as insects and dirt.

Each concentrator has additional structural components: a small steel strut and a harness. The steel strut, tethered in place, holds the cell at the focal point inside the concentrator and provides a conduit for a small water loop that cools the cell. A lightweight, flexible steel band forms a harness around the circumference of the concentrator and is used to hold and point the concentrator.

A Support System Holds It All in Place…

The concentrators are suspended with our patented support system, which is based on the architectural principles of tensegrity. The resulting system of wood posts and steel cables uses a minimum amount of material, has a small footprint, and causes the least disruption to the natural environment of any solar power plant.

Our design philosophy demands a system that scales plausibly so that the costs of constructing and maintaining our power plants can compete with those of conventional fossil fuel power plants. This means we can’t use rare materials or otherwise expensive materials. In fact, the materials have to be among the most abundant in nature and industry. The primary materials choices for our concentrators—plastic film and air—are critical to making our solution economically competitive.

Plastic film, the basis of our patented concentrator design, is the only man-made material produced in enough abundance to meet our scaling needs for a collector material. All in all, 744-billion square feet of PET (polyethylene terephthalate) polyester film—which is the type of plastic we use in our design—is produced worldwide every year for packaging and other uses. This total could create enough Cool Earth concentrators to produce 6,482 terawatt-hours (TWh) annually. Each concentrator uses about two pounds of plastic.

Air is used to inflate our concentrators. We’re talking regular, breathable, nothing-fancy air, provided freely by nature. Each concentrator uses about five pounds of air.

As for other materials, we take a minimalist approach in their use. For instance, we use a very small amount of aluminum to create the thin (a few micrometers thick) reflective layer for each concentrator. And how small is “very small?” The average aluminum soda can has enough material to create reflective surfaces for about 725 of our concentrators.

Visit Cool Earth…

More about Eric Cummings…

Now if Cumming’s and company can provide us with a way to make highly efficient inexpensive solar collectors then we still need a way to efficiently store that electrical energy. After all the sun doesn’t shine at night. Environmental engineer Fouad Khan thinks the thinkers at MIT may have found such a way. They began by asking themselves, how do plants store energy for use when there is no sunlight?

MIT News—Until now, solar power has been a daytime-only energy source, because storing extra solar energy for later use is prohibitively expensive and grossly inefficient. With today’s announcement, MIT researchers have hit upon a simple, inexpensive, highly efficient process for storing solar energy.

Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun. “This is the nirvana of what we’ve been talking about for years,” said MIT’s Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. “Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon.”

Inspired by the photosynthesis performed by plants, Nocera and Matthew Kanan, a postdoctoral fellow in Nocera’s lab, have developed an unprecedented process that will allow the sun’s energy to be used to split water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating carbon-free electricity to power your house or your electric car, day or night.

The key component in Nocera and Kanan’s new process is a new catalyst that produces oxygen gas from water; another catalyst produces valuable hydrogen gas. The new catalyst consists of cobalt metal, phosphate and an electrode, placed in water. When electricity—whether from a photovoltaic cell, a wind turbine or any other source—runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced.

Combined with another catalyst, such as platinum, that can produce hydrogen gas from water, the system can duplicate the water splitting reaction that occurs during photosynthesis.

The new catalyst works at room temperature, in neutral pH water, and it’s easy to set up, Nocera said. “That’s why I know this is going to work. It’s so easy to implement,” he said. ‘Giant leap’ for clean energy

Sunlight has the greatest potential of any power source to solve the world’s energy problems, said Nocera. In one hour, enough sunlight strikes the Earth to provide the entire planet’s energy needs for one year.

The following description of their process is reposted from the Nocera Lab at MIT.

Daniel G. Nocera

Photosynthesis Chemistry of Renewable Energy

A great technological challenge facing our global future is the development of renewable energy. Rising standards of living in a growing world population will cause global energy consumption to increase dramatically over the next half-century. Energy consumption is predicted to increase at least two-fold, from our current burn rate of 12.8 TW to 28 – 35 TW by 2050. A short-term response to this challenge is the use of methane and other petroleum-based fuels as hydrogen sources. However, external factors of economy, environment, and security dictate that this energy need be met by renewable and sustainable sources with water emerging prominently as the primary carbon-neutral hydrogen source and light as an energy input. This area of research in our group is summarized by a simple equation:

solar light + H2O = fuel

The above equation is aimed at driving the energetically unfavorable, water-splitting reaction to produce fuel – hydrogen and oxygen. The photon may be captured directly by a transition metal catalyst or indirectly by a transition metal catalyst at the surface of a photovoltaic (PV) cell. The transition metal complex can the use the solar converted energy (from the PV or directly) to act on water and rearrange its bonds to produce hydrogen and oxygen – a solar fuel. In this way, solar photons are converted into high-energy chemical bonds, the energy of which can be released in a fuel cell. The construction of such a cycle, however, reveals daunting challenges because it relies on chemical transformations that are not understood at the most basic levels. Unexplored basic science issues are immediately confronted when the water splitting problem is posed in the simplest chemistry framework,

The overall transformation is challenging because: (1) It is a multielectron process, (2) proton transfer must accompany electron transfer (i.e., PCET) – both electron and proton inventories need to be managed, and (3) strong bonds need to be activated to close a catalytic cycle.

This photochemical water splitting problem shares basic chemical commonalities with the activation of other small molecules of energy consequence, including CO2, N2 and CH4, H2 and O2. All involve bond-making and –breaking processes that require multielectron transfers often coupled to proton transfer events. Our research efforts have addressed the foregoing italicized research themes by expanding the reactivity of metal complexes in ground and electronic excited states beyond conventional one-electron transfer. We have created molecules that react in multielectron steps from their electronic excited states. We have been examining the coupling of electrons and protons in catalytic small molecule reactions (see PCET section for more information). We are inventing a myriad of new ways to photoactivate stable metal-ligand bonds, especially those involving oxygen. Against this backdrop of knowledge, hydrogen- and oxygen-producing catalysts have been developed and are continually being improved.

Original Article with References…


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