Naturally efficient

By Lars Krone
In the animal kingdom, a great diversity of strategies for an energy-efficient way of life has developed in the course of evolution. “tomorrow” presents fauna’s efficiency kings.
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Sailing champion

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In spite of a major disadvantage, it’s the champion of long-distance flying: the wandering albatross. Just by flapping its wings it could hardly stay airborne because its muscle power is simply not enough for its body weight, which can be as much as twelve kilograms (26 lb). The albatross has resolved this problem by perfecting its ability to glide, allowing it to cover a distance of up 1,000 kilometers (621 miles) per day on a minimal energy budget. As early as in 1937, the Swiss geologist Arnold Heim called it “by far the world’s best glider.” The albatross leverages its anatomy and sophisticated flying techniques to achieve this feat. A special mechanism in the elbow and shoulder joints allows it to lock its extended wings – the wing span may be as large as 3.70 meters (12.13 ft) – without having to put its muscles to work.

In 2012, a research team from TU Munich investigated these extreme flyers. They equipped 20 wandering albatrosses with GPS transmitters and tracked their flight routes. As a result, they found out that just above the water surface the birds turn into the wind with their wings spread and then rise due to the resulting lift. At an altitude of 10 to 15 meters (33–49 ft) – where a strong wind blows – they gather new energy in a steep trajectory and sail back with the wind toward the surface of the sea. The fact that the bird’s heart rate in the air is nearly the same as its resting heart rate shows that the effort the albatross has to exert in flight is minimal. Its adaptability is of benefit to another energy-saving measure developed by this long-distance flyer: it has learned to make use of the upward flow of warm air produced by large vessels.

Suction power

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Although almost 99 percent of what they’re made up of is water, there’s more to jellyfish than meets the eye. U.S. researchers have found out that the slippery sea creatures have developed one of the most efficient propulsion systems in the animal world. For a long time, it was assumed that jellyfish primarily push against the water behind them for propulsion. But current research by a team from Stanford University in California has yielded new findings. “Our experiments show that jellyfish actually suck water toward themselves to move forward instead of pushing against the water behind them, as had been previously supposed,” writes biophysicist John Dabiri.

As the jelly’s umbrella-shaped plume collapses, water ahead of the animal is pulled aft, propelling the jellyfish forward, by 45 percent more compared with only pushing against the water behind them. The fact that muscle mass accounts for only about one percent of a jelly’s body weight – compared to fish where the ratio is about 50 – shows the efficiency of this form of propulsion. The research team drew another interesting conclusion. The energy saved in propulsion is invested in growth. As a result, jellyfish can grow to a diameter of more than two meters (6.5 ft), which clearly makes it easier for them to catch prey.

Time for a break

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Flat-out during the day and half-dead at night – the life of hummingbirds alternates between two extremes. These pip-squeaks weighing no more than two to 20 grams (0.07 to 0.70 oz) have extreme maneuvering skills – even hovering and flying backward is no problem – and they achieve speeds of more than 100 km/h (62.13 mph). Their secret lies in hovering by moving their wingtips up to 90 times per second in a figure-eight pattern with the eight lying on its side – an absolute record in the birds’ world.

Some hummingbird species have heart rates of 1,200 per minute. For all this, the birds need an immense amount of energy: 250 calories per hour – as much as a man weighing 70 kilos (154 lb). To cover its energy needs, a hummingbird has to empty between one and two thousand flowers per day. The amount of nectar absorbed this way equates to more than half of their body weight. During their twelve-hour sleep at night, they reduce their physical functions by 90 percent and go into a hibernation-like state called torpor. While in torpor, bee hummingbirds whose habitat is Cuba for instance lower their body temperature from 40 °C to 18 °C (104 °F to 64.4 °F).

Life in slow motion

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Sloths lead their lives in energy-saving mode,” says Prof. Dr. Martin S. Fischer, Chair of Systematic Zoology and Evolutionary Biology at University of Jena, Germany. Due to their laid-back lifestyle that has them near-exclusively living in trees, these unusual animals are still baffling researchers in many respects. They sleep about 16 hours per day and move very little. And even in climbing, efficiency plays a major role, as Fischer’s colleague at University of Jena, Dr. John Nyakatura, explains in a research paper. In the evolution of sloths, he says, “a dislocation of certain muscular contact points occurred which enabled them to keep their own body weight with a minimum of energy input.”

Their diet explains why such low energy consumption is essential to their survival. Sloths have specialized in eating low-energy leaves. To extract a maximum of nutrients from them, sloths have the slowest metabolism of all mammals. It may take them up to a month to completely digest a single meal. To enable them to ingest other nutrients without expending a major effort, sloths have developed an unusual symbiosis with algae and moths living in their thick coat of fur. The algae with their shimmering green not only enhance the sloths’ camouflage but also provide additional nutrients. To ingest the nutrients of the algae, the sloths lick them while grooming their fur coats. To some extent, the algae are even directly absorbed through the skin. The moths provide nutrients to the algae through their feces and in turn deposit their eggs in the feces of the sloths.

In full swing

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They’re the giants of the treetops. With a height of up to 1.50 meters (4.9 ft), orangutans are the world’s largest tree-dwellers. Their diet is austere, the menu primarily consisting of low-calorie fruits, so saving energy is important. Orangutans spend the major part of the day snoozing for hours on end. As a result, in relation to their height, these anthropoid apes taking in 1,200 to 2,000 calories per day consume less energy than most mammals. But their strenuous climbing in search of food continually takes the primates to their energy limits. How they manage their energy budget was investigated by British scientist Dr. Lewis Halsey from the University of Roehampton.

His research was focused on finding out how orangutans get from tree to tree. They have three options available to them. First: climb down, run to the next tree and climb up again. Second: jump from tree to tree. And the third and most efficient one: sway a branch until you’re able to reach the branch of another tree. Halsey found out that swaying is most efficient. Only young animals jump because they lack the strength to bend stiff branches. So, the larger and heavier they are, the more efficiently orangutans can move around. The arboreal apes instinctively adapt their movements to keep from incurring an energy deficit. Halsey: “One thing that’s even more strenuous than climbing up a tree is pulling oneself up a vine the way Tarzan used to in the movies.”

Formed to perfection

How foolish of Mother Nature: penguins are birds but they can’t fly. On land, they’re incredibly clumsy but in water, they’re in their element. The perfection with which they swim even eclipses that of most fish – their main food. Under water, penguins achieve speeds of more than 40 km/h (24.85 mph) although the effort they exert is minimal. The energy in one liter (0.26 gal) of gasoline would allow a penguin to swim a distance of 1,500 kilometers (932 miles).

One reason that enables them to do so is the highly streamlined shape of their bodies. “The wave-shaped front of the body with a concave-convex transition between the beak, head and torso is particularly conspicuous,” explains bionics expert Stefan Löffler in his doctoral thesis. In addition, “all torsos have a near-circular frontal area and the length-thickness ratios (4 : 1) of their bodies are within the range of volume-optimized laminar spindles.” Flow around the penguins’ body shape is nearly ideal, in other words with zero loss. There are no major separations and turbulences. Plus, penguins use another trick: the air stored in their plumage escapes in the form of small bubbles when they dive. This micro-bubble effect reduces drag even further.

“Nature is an outstanding provider of ideas”
Naturally efficient© Schaeffler

In bionics, scientists use nature as a role model for new technology. In an interview, Prof. Dr.-Ing. Tim Hosenfeldt, Senior Vice President, Corporate Innovation, talks about its significance for Schaeffler.

As an engineer, what fascinates you about nature?
It is very exciting to watch how nature optimally adapts to the conditions and requirements of its environment. In doing so, it uses the available energy as resource-efficiently as possible. There are many challenges or problems we are facing today where a look at nature would be useful. In many cases, nature has already developed something that has become a successful evolution and that we can adapt.

Can you name some examples?
A very interesting aspect, for example, is structural mechanics and lightweight design – both in flora and fauna. For instance, in highly stressed places, the fibers of trees grow in a special direction for greater stability. With birds on the other hand, lightweight design is the appropriate solution for energy-efficient flight. Particularly fascinating as well are nature’s self-healing powers. That is what we would obviously like to develop for materials as well. But the field of surface design can be mentioned in this context too. By using the lotus effect, surfaces can easily be kept clean. And providing ships with a so-called shark skin can reduce friction, which lowers their energy consumption.

What role does bionics play at Schaeffler?
In our “mobility for tomorrow” strategy, for instance, lightweight design is an important factor. In this context, nature has created many role models that show how resource-efficient lightweight design can work. This has resulted in new possibilities in engineering design and manufacturing. Lightweight design, for example, is applied in our drawn roller bearings. Another positive example is the development of a CVT (continually variable transmission) for which, as far back as 15 years ago, we took advantage of the laws of nature in optimizing the strength of link-chain plates.

What departments at Schaeffler are involved in bionics?
We foster a company-wide exchange about key topics of the future. This obviously includes bionics. Our Forum of Inspiration that serves to exchange ideas about future projects and developments and our Technology Dialog where we lay the foundations for the most important developments of the next five to ten years are important platforms. But we also engage in exchanges with external partners from the research community, industry and with startups as well.

Will bionics be playing an even greater role in the future? Talking about energy efficiency …
Definitely so. The continually growing demand for electric vehicles is a case in point. Due to the heavy batteries, lightweight design is a very important factor in terms of energy efficiency. Generally, the rule applies that the lighter the vehicles become, the lower will be their energy consumption. Nature is an outstanding provider of ideas for innovative lightweight design. We want to counteract global warming by reducing CO2 emissions and using fewer fossil fuels. In this context, we are involved in the field of renewable energy generation, as well as in projects that look at possibilities of chemically storing this energy the way nature does – which is in gaseous or liquid form as methane or as synthetic fuel. Artificial intelligence and self-learning systems will be playing a greater role in the context of increasing automated mobility. These systems learn based on data from which they generate knowledge – and they do so in the spirit of our vision for a world that will be cleaner, safer and more intelligent.

Naturally efficient© Schaeffler
Bionic example

Due to its hybrid plastic-metal design, the weight of a wheel bearing, compared with the conventional design (left), was reduced by 440 grams (15.5 oz) in predevelopment. The utilization of bionic structures with a topology optimization of the plastic component reduces the load of the material by 20 to 30 percent.

Lars Krone
Author Lars Krone
He grew up with dogs, cats and chickens in rural Westphalia. Now Lars Krone (39) lives in Hamburg – without any animals whatsoever. Today, he nurtures his passion for nature primarily during seaside vacations.