Future cities could be lit by algae

[Denmark] The way we produce light has changed surprisingly little since Thomas Edison developed the first light bulb in 1879.

The LED-bulb has recently reduced electricity costs significantly, but they still use the same power source and continue to contribute to global warming since most electricity still comes from burning fossil fuels.

We need a new method to produce light that instead of using conventional electricity uses nature’s own energy.

In the US a few dedicated researchers have been investigating bioluminescent algae for some years, but they have never successfully mapped the whole bioluminescent system within the algae. At the Technical University of Denmark (DTU), we are conducting the first Danish research in this area, and it shows that bioluminescent organisms could one day light up our cities in a turquoise blue light.

There are however, some clear challenges to solve before this becomes a reality. We may need to transfer genes from bioluminescent organisms into other green organisms, perhaps higher plants that will be able to emit light more effectively.

Microalgae illuminate the dark

Algae is found everywhere on land and in the sea, and are immensely important for life as we know it.

Bioluminescent algae light up the dark. This bright blue light could illuminate cities in the future. (Photo: Mikal Schlosser)

Many people associate algae with seaweed (macroalgae), but in fact most algae are micro algae. These algae are so small that you can only see them through a microscope.

Some of them, so-called dinoflagellates, emit a strong blue light at night. This phenomenon is known as bioluminescence, whereby living organisms produce light via chemical reactions.

You can see it yourself at certain times of the year in warmer climates, around the equator from Brazil to Australia.

Two molecules meet and produce light

Even though people have observed this phenomenon in the ocean for more than 2,500 years, we still know surprisingly little about the algae involved and how they produce light.

The luciferase enzyme (yellow Pacman) becomes active at pH 6. It binds with luciferin (green wedge), transferring energy via oxidation, which is emitted as blue light. (Illustration: Signe Friis Schack, Allumen IVS)

The algae emit a blue light when they are shaken. Such as, when a predator swims by creating a current, or when the algae are hit by waves in coastal waters.

Two molecules are particularly important for light production: Luciferase (an enzyme) and luciferin (a molecule produced by photosynthesis).

When algae register a disturbance, a chain of cellular chemical processes is set in motion causing the pH to drop. This activates the luciferase enzymes, which bind to the luciferin and transfer energy to the luciferin via a process known as oxidation. It is the release of energy from luciferin we see as blue light.

It has so far only been shown theoretically and not by experiment.

Biological solar cell and living lamp in the same organism
The bioluminescent algae need energy to emit light, just like your bedside lamp that plugs into a power socket to access electricity. Algae though, get their energy from another source: The Sun.

They use sunlight to produce energy via photosynthesis to carry out a whole range of processes at the cellular level.

You can imagine algae as tiny individual lamps, powered by a solar cell. They ‘recharge’ during the day so they can emit their blue light throughout the night.

There are a number of bioluminescent animals, fungi, and bacteria. All of them require food to produce energy needed to illuminate. Algae exploit sunlight and carbon dioxide (CO2): Two inexhaustible, environmentally friendly, CO2-neutral sources of energy.


Photo: Artist’s impression of a bioluminescent city lit by bioluminescent plants and algae. (Illustration: Signe Friis Schack, Allumen IVS)

View original article at: Future cities could be lit by algae

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