Biomimicry: powering the world with lessons from nature

Australia-based tidal power technology company BPS has developed two different tidal energy devices based on sea life, allowing for better hydrodynamics.

Its bioWAVE tidal power device mimics the swaying of undersea plants, using ocean swells to generate power. This would mean more consistent power supply than the more common lunar tide approach.

This technology needs to capture movement from waves, but too much resistance could damage the machine. Because of this, the machine mimics the shape of sea plants to allow water to pass through where needed.

The company has also developed a smaller tidal energy system modelled around fish fins. The bioSTREAM tidal generator is shaped to move through water while moving back and forth with waves. This reduces wear, but also means less of an environmental impact. This slow movement then creates hydraulic pressure and becomes electricity sent to shore via a cable.

In many countries, species of the kingfisher watch over rivers, looking for the perfect time to dive for small fish. When a kingfisher enters the water, it creates almost no disturbance to the surface. The naturally piercing shape of its beak has inspired numerous designs, including the famous Japanese Shinkansen bullet train.

It also gave Biome Renewables the idea for the PowerCone®. This device fits onto the centre of existing turbines and uses its spiral shape to redistribute more air toward the turbine blades. The company says that this makes the turbine more aerodynamic, and more efficient.

This would mean less noise and more power, bringing turbines up to their minimum load sooner. Biome Renewables promises a 13% increase on power generation from their product.

When redesigning concentrated solar arrays to save space, Professor Alexander Mitsos, Rockwell International assistant professor of mechanical engineering at the Massachusetts Institute of Technology, found the layout resembled the spiral of many flower petals.

Many flowers arrange their petals and seeds according to the mathematical series known as the Fibonacci sequence. This pattern comes from adding the two previous numbers: 1, 1, 2, 3, 5, 8, 13, and so on.

For many flowers, the number of seeds in any spiral from the centre of the bloom will be a Fibonacci number. Impressively, this usually works in both directions.

Botanists have theorised that this arrangement might help flowers pack in as many seeds as possible. In his study, Professor Mitsos said arranging solar reflectors like this could shrink the area needed for panels by 20% while not affecting the power output.

He told Wired: “Concentrated solar thermal energy needs huge areas. If we're talking about going to 100% or even 10% renewables, we will need huge areas, so we better use them efficiently.”

Sunflowers have also inspired innovations to photovoltaic panels. When in bloom, sunflower heads naturally follow the sun through the daytime sky. If static solar panels could passively do the same, analyst firm WoodMackenzie estimates that they would generate up to 35% more energy.

Photovoltaic cells operate best when sunlight is directly facing them, but most panels remain static as the sun moves around them. Panels can be made to rotate in one or two directions, each increasing their potential generation.

Most systems do this with motors, which means energy and maintenance costs. Furthermore, their weight and expense often rules them out for domestic buyers. Because of these factors, several companies and universities have aimed to make their panel mounts more like sunflower heads, which naturally follow the sun throughout the day.

One team from the Massachusetts Institute of Technology mounted a test solar module on an arch made of two metals. As the sun warmed these, they expanded and deformed to alter the angle of the panel on top.

Elsewhere, engineers worked on systems light enough to be mounted on the roofs of homes. Engineers at SunPoint Technology designed a mechanical system to angle their solar panels, which they said could passively generate 23% more energy.

While solar heliotropes aim to fix the problem of decreased generation, another biomimicry design simply aims to remove the problem.

Researchers from the California Institute of Technology in the US and Karlsruhe Institute of Technology (KIT) in Germany were looking to improve the efficiency of thin-film solar photovoltaic cells. KIT researcher Radnawul Siddique told Popular Mechanics: “I was in a conference and somebody was presenting about butterflies and their nanostructures, and I was intrigued. A lot of insects take their colours from nanostructures.”

In the case of the rose butterfly, the black colour of their wings helps them efficiently absorb light for warmth. To find this light-absorbing structure, the researchers then looked at the butterfly under an electron microscope.

The research teams found the wings to be full of microscopic holes, which scattered the light hitting them. This in turn meant the butterfly could absorb more heat, and that solar panels could use this structure to absorb more energy.

The teams published their findings in the Science Advances journal. Their study produced a photovoltaic panel design based on this structure, which captured approximately twice as much light when directly under the light source. At angles of up to 50°, similar to evening sun, the panels caught up to three times as much light. In July, further research at the University of Oulu studied more butterflies, and managed to increase short-circuit current by 66%.

Another turbine innovation took inspiration from the pectoral fins of humpback whales. The shape of these front “flippers” has evolved to include small bumps on their leading edge, known as tubercles.

The shape of the tubercles pushes oncoming water into more compressed, faster-flowing streams between the bumps. This reduces the drag of the fin, allowing the whales to move faster through the water.

The same effect applies to wind turbine blades, which can use tubercles to turn faster with less drag, generating more energy. The concept also applies to helicopter rotors and fan blades, meaning less energy used. Toronto-based company Whalepower has tested one design, generating power from 10 mph winds that would usually need 17 mph.

While many natural sources have influenced innovation in wind turbines, one university team found a way to get rid of the turbine entirely.

The Vibro-Wind Research Group at Cornell University in the US designed a machine to convert vibrations from wind energy into electricity. The design took inspiration from the fluttering of leaves in the breeze, and how plants treat that energy. Where natural designs disperse the energy, the university team would aim to capture it.

The design uses piezoelectric elements to create an estimated 54W/m². Comparatively, standard photovoltaic solar panels generate approximately 60-100W/m². The prototype also starts generating electricity with wind speeds of 2m/s, significantly lower than the 9m/s usually required for wind generation.

The team hopes the design will appeal to urban residents, because of its small size, small footprint and appealing design.