The variety of humble algae that cover the surface of ponds and seas could be the key to increasing the efficiency of artificial photosynthesis, allowing scientists to produce more energy and reduce waste in the process.
A study by scientists from Nanyang Technological University of Singapore (NTU Singapore) showed how encapsulating algae proteins in liquid droplets can dramatically improve light harvesting properties and light harvesting properties by up to three times. energy conversion of algae. This energy is produced when algae undergo photosynthesis, which is the process used by plants, algae, and some bacteria to harness the energy of sunlight and transform it into chemical energy.
By mimicking the way plants convert sunlight into energy, artificial photosynthesis can be a sustainable way to generate electricity that is not dependent on fossil fuels or natural gas, which is not renewable. Since the rate of conversion of natural energy from sunlight to electricity is low, increasing total electricity production could make artificial photosynthesis commercially viable.
The study, led by assistant professor Chen Yu-Cheng of the School of Electrical and Electronic Engineering, looked at a particular type of protein found in red algae. These proteins, called phycobiliproteins, are responsible for absorbing light into algal cells to initiate photosynthesis.
Phycobiliproteins recover light energy across the entire spectral range of light wavelengths, including those that chlorophylls do not absorb well, and convert it into electricity.
Assistant Professor Chen said, “Due to their unique light-emitting and photosynthetic properties, phycobiliproteins have promising potential applications in biotechnology and semiconductor devices. Increasing the energy of the light harvesting apparatus has been the focus of development efforts for organic devices. who use light as a source of energy. “
The team’s research could lead to a new, sustainable way to generate electricity from the sun that does not rely on fossil fuels or natural gas, which are not renewable. A new bio-inspired technology based on phycobiliproteins could be used to make more efficient solar cells and pave the way for greater efficiency within artificial photosynthesis.
The use of algae as a source of biological energy is a popular topic of interest in sustainability and renewable energy, as the use of algae potentially reduces the amount of toxic by-products created during manufacturing. solar panels.
The study supports NTU’s commitment to sustainability as part of its 2025 strategic plan, which seeks to understand, articulate and address humanity’s impact on the environment.
The results were published and selected as the cover of a scientific journal ACS Applied Material Interfaces.
Triple the efficiency of artificial photosynthesis
Microalgae absorb sunlight and convert it into energy. In order to amplify the amount of energy that algae can generate, the research team developed a method to enclose red algae in small 20-40 micron liquid crystal micro-droplets and expose them to light.
When light hits the droplet, an effect known as “gallery whisper mode” occurs, in which light waves travel around the curved edges of the droplet. The light is effectively trapped in the droplet for a longer period of time, providing more opportunities for photosynthesis and thus generating more energy.
The energy generated during photosynthesis in the form of free electrons can then be picked up by electrodes in the form of electric current.
“The droplet behaves like a resonator that confines a lot of light,” Assistant Professor Chen said. “This gives the algae more exposure to light, increasing the rate of photosynthesis. A similar result can be achieved by also coating the outside of the droplet with the algae protein.”
“By exploiting the microdroplets as a carrier for light harvesting biomaterials, the strong improvement of the local electric field and the confinement of photons inside the droplet resulted in considerably higher electricity production”, a- he declared.
The droplets can be easily produced in bulk at low cost, making the research team’s method widely applicable.
According to Assistant Professor Chen, most algae-based solar cells produce an electrical power of 20 to 30 microwatts per square centimeter (µW / cm2). The NTU algae-droplet combination increased this level of energy production at least two to three times, compared to the rate of energy production of algae protein alone.
Converting “bio-waste” into bioenergy
Artificial photosynthesis aims to replicate the natural biological process by which plants convert sunlight into chemical energy. The aim is to establish a way to make energy renewable, reliable and storable without negatively impacting the environment.
One of the challenges of artificial photosynthesis is to generate energy as efficiently as other sources of solar energy, such as solar panels. On average, solar panels have an efficiency rate of 15-20%, while artificial photosynthesis is currently estimated at 4.5%.
Assistant Professor Chen said, “Artificial photosynthesis is not as efficient as solar cells at generating electricity. However, it is more renewable and sustainable. Due to the growing interest in environmentally friendly technologies. ‘Environmentally and renewable, energy extraction from light harvesting proteins in has generated substantial interest in the field of bioenergy.
Assistant Professor Chen envisions a potential use case of “algae farms,” where densely growing algae in bodies of water could potentially be combined with larger liquid crystal droplets to create power generators. floating.
“The micro-droplets used in our experiments have the potential to be transformed into larger droplets which can then be applied to algae outside of a laboratory environment to create energy. Although some may consider the growth of algae as unsightly, they play a very important role in the environment. Our results show that there is a way to convert what some might consider “bio-waste” into bio-energy, “Assistant Professor Chen said.
