̽��ֱ�� of Cambridge - fuel cell

Harnessing the power of algae: new, greener fuel cells move step closer to reality

cjb250 — Wed, 10 Jan 2018 11:18:27 +0000

As the global population increases, so too does energy demand. ̽��ֱ��threat of climate change means that there is an urgent need to find cleaner, renewable alternatives to fossil fuels that do not contribute extensive amounts of greenhouse gases with potentially devastating consequences on our ecosystem. Solar power is considered to be a particularly attractive source as on average the Earth receives around 10,000 times more energy from the sun in a given time than is required by human consumption.

In recent years, in addition to synthetic photovoltaic devices, biophotovoltaics (BPVs, also known as biological solar-cells) have emerged as an environmentally-friendly and low-cost approach to harvesting solar energy and converting it into electrical current. These solar cells utilise the photosynthetic properties of microorganisms such as algae to convert light into electric current that can be used to provide electricity.

During photosynthesis, algae produce electrons, some of which are exported outside the cell where they can provide electric current to power devices. To date, all the BPVs demonstrated have located charging (light harvesting and electron generation) and power delivery (transfer to the electrical circuit) in a single compartment; the electrons generate current as soon as they have been secreted.

In a new technique described in the journal Nature Energy, researchers from the departments of Biochemistry, Chemistry and Physics have collaborated to develop a two-chamber BPV system where the two core processes involved in the operation of a solar cell – generation of electrons and their conversion to power – are separated.

“Charging and power delivery often have conflicting requirements,” explains Kadi Liis Saar, of the Department of Chemistry. “For example, the charging unit needs to be exposed to sunlight to allow efficient charging, whereas the power delivery part does not require exposure to light but should be effective at converting the electrons to current with minimal losses.”

Building a two-chamber system allowed the researchers to design the two units independently and through this optimise the performance of the processes simultaneously.

“Separating out charging and power delivery meant we were able to enhance the performance of the power delivery unit through miniaturisation,” explains Professor Tuomas Knowles from the Department of Chemistry and the Cavendish Laboratory. “At miniature scales, fluids behave very differently, enabling us to design cells that are more efficient, with lower internal resistance and decreased electrical losses.”

̽��ֱ��team used algae that had been genetically modified to carry mutations that enable the cells to minimise the amount of electric charge dissipated non-productively during photosynthesis. Together with the new design, this enabled the researchers to build a biophotovoltaic cell with a power density of 0.5 W/m2, five times that of their previous design. While this is still only around a tenth of the power density provided by conventional solar fuel cells, these new BPVs have several attractive features, they say.

"While conventional silicon-based solar cells are more efficient than algae-powered cells in the fraction of the sun’s energy they turn to electrical energy, there are attractive possibilities with other types of materials," says Professor Christopher Howe from the Department of Biochemistry. “In particular, because algae grow and divide naturally, systems based on them may require less energy investment and can be produced in a decentralised fashion."

Separating the energy generation and storage components has other advantages, too, say the researchers. ̽��ֱ��charge can be stored, rather than having to be used immediately – meaning that the charge could be generated during daylight and then used at night-time.

While algae-powered fuel cells are unlikely to generate enough electricity to power a grid system, they may be particularly useful in areas such as rural Africa, where sunlight is in abundance but there is no existing electric grid system. In addition, whereas semiconductor-based synthetic photovoltaics are usually produced in dedicated facilities away from where they are used, the production of BPVs could be carried out directly by the local community, say the researchers.

“This a big step forward in the search for alternative, greener fuels,” says Dr Paolo Bombelli, from the Department of Biochemistry. “We believe these developments will bring algal-based systems closer to practical implementation.”

̽��ֱ��research was supported by the Leverhulme Trust, the Engineering and Physical Sciences Research Council and the European Research Council.

Reference
Saar, KL et al. Enhancing power density of biophotovoltaics by decoupling storage and power delivery. Nature Energy; 9 Jan 2018; DOI: 10.1038/s41560-017-0073-0

A new design of algae-powered fuel cells that is five times more efficient than existing plant and algal models, as well as being potentially more cost-effective to produce and practical to use, has been developed by researchers at the ̽��ֱ�� of Cambridge.

This a big step forward in the search for alternative, greener fuels

Paolo Bombelli

Kadi Liis Saar

Artist' impression

Researcher Profile: Dr Paolo Bombelli

Dr Paolo Bombelli is a post-doctoral researcher in the Department of Biochemistry, where his research looks to utilise the photosynthetic and metabolic activity of plants, algae and bacteria to create biophotovoltaic devices, a sustainable source of renewable current. He describes himself as “a plants, algae and bacteria electrician”.

“Photosynthesis generates a flow of electrons that keeps plants, algae and other photosynthetic organisms alive,” he explains. “These electrons flow though biological wires and, like the electrical current obtained from a battery and used to power a radio, they are the driving force for any cellular activity.”

Dr Bombelli’s fascination with this area of research began during his undergraduate studies at the ̽��ֱ�� of Milan.

“Plants, algae and photosynthetic bacteria are the oldest, most common and effective solar panels on our planet,” he says. “For billions of years they have been harnessing the energy of the sun and using it to provide oxygen, food and materials to support life. With my work I aim to provide new ways to embrace the potential of these fantastic photosynthetic organisms.”

His work is highly cross-disciplinary, with input from the Departments of Biochemistry, Plant Sciences, Chemistry and Physics, and the Institute for Manufacturing, as well as from researchers at Imperial College London, UCL, the ̽��ֱ�� of Brighton, the Institute for Advanced Architecture of Catalonia in Spain and the ̽��ֱ�� of Cape Town, South Africa.

“Universities are great places to work and so they attract many people,” he says. “People choose to come to Cambridge because they know the ideas they generate here will go on to change the world.”

In 2016, Dr Bombelli won a Public Engagement with Research Award by the ̽��ֱ�� of Cambridge for his work engaging audiences at more than 40 public events, including science festivals and design fairs, reaching thousands of people in seven countries. His outreach work included working with Professor Chris Howe to develop a prototype ‘green bus shelter’ where plants, classical solar panels and bio-electrochemical systems operate in synergy in a single structure.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Fuel cell electrolyte developed to offer cleaner, more efficient energy

sc604 — Wed, 20 Jan 2016 16:29:50 +0000

These new materials offer the possibility of either significantly improving the efficiency of current high-temperature fuel cell systems, or achieving the same performance levels at much lower temperatures. Either of these approaches could enable much lower fuel consumption and waste energy. ̽��ֱ��material was co-invented by Professor Judith Driscoll of the Department of Materials Science and Metallurgy and her colleague Dr Shinbuhm Lee, with support from collaborators at Imperial College and at three different labs in the US.

Solid oxide fuel cells are comprised of a negative electrode (cathode) and positive electrode (anode), with an electrolyte material sandwiched between them. ̽��ֱ��electrolyte transports oxygen ions from the cathode to the anode, generating an electric charge. Compared to conventional batteries, fuel cells have the potential to run indefinitely, if supplied by a source of fuel such as hydrogen or a hydrocarbon, and a source of oxygen.

By using thin-film electrolyte layers, micro solid oxide fuel cells offer a concentrated energy source, with potential applications in portable power sources for electronic consumer or medical devices, or those that need uninterruptable power supplies such as those used by the military or in recreational vehicles.

“With low power requirements and low levels of polluting emissions, these fuel cells offer an environmentally attractive solution for many power source applications,” said Dr Charlanne Ward of Cambridge Enterprise, the ̽��ֱ��’s commercialisation arm, which is managing the patent that was filed in the US. “This opportunity has the potential to revolutionise the power supply problem of portable electronics, by improving both the energy available from the power source and safety, compared with today’s battery solutions.”

In addition to providing significantly improved conductivity, the new electrolyte material offers:

minimal heat loss and short circuiting due to low electronic conductivity
minimal cracking under heat cycling stress due to small feature size in the construction
high density, reducing the risk of fuel leaks
simple fabrication using standard epitaxial growth and self-assembly techniques

“ ̽��ֱ��ability to precisely engineer and tune highly crystalline materials at the nanoscale is absolutely key for next-generation power generation and storage of many different kinds,” said Driscoll. “Our new methods and understanding have allowed us to exploit the very special properties of nanomaterials in a practical and stable thin-film configuration, resulting in a much improved oxygen ion conducting material.”

In October, a paper on the enhancement of oxygen ion conductivity in oxides was published in Nature Communications. It is this enhancement that improves efficiency and enables low-temperature operation of fuel cells. As a result of the reported advantages, the novel electrolyte material can also potentially be used in the fabrication of improved electrochemical gas sensors and oxygen separation membranes (to extract oxygen molecules from the air). ̽��ֱ��inventors have also published two other papers showing the enhanced ionic conduction in different materials systems, one in Nano Letters and one in Advanced Functional Materials.

Cambridge Enterprise is working with Driscoll to take the technology to market, seeking to collaborate with a fuel cell manufacturer with expertise in thin-film techniques to validate the new material.

A new thin-film electrolyte material that helps solid oxide fuel cells operate more efficiently and cheaply than those composed of conventional materials, and has potential applications for portable power sources, has been developed at the ̽��ֱ�� of Cambridge.

̽��ֱ��ability to precisely engineer and tune highly crystalline materials at the nanoscale is absolutely key for next-generation power generation and storage of many different kinds.

Judith Driscoll

Bloom Energy

Bloom Energy Fuel Cell

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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̽��ֱ��hidden power of moss

amb206 — Thu, 22 Sep 2011 05:03:47 +0000

Moss is regarded as a menace by gardeners who seek to eradicate it from their lawns. Now researchers all over the world are exploring how moss, algae and plants could be used as a source of renewable energy in the future.

A team of designers and scientists at Cambridge ̽��ֱ�� will be exhibiting a novel moss table at the London Design Festival later this week. ̽��ֱ��prototype table will showcase an emerging technology called biophotovoltaics (BPV) which uses the natural process of photosynthesis to generate electrical energy.

Featuring biological fuel cells made from moss, the table has been created as a vision of the future by Alex Driver and Carlos Peralta from Cambridge’s Institute for Manufacturing and Paolo Bombelli from the ̽��ֱ��’s Chemical Engineering and Biotechnology Department.

Still at early stages, BPV has the potential to power small devices such as digital clocks. Low cost BPV devices may become competitive alternatives to conventional renewable technologies such as bio-fuels in the next ten years.

̽��ֱ��appeal of BPV lies in its ability to harness a natural process that takes place all around us. Photosynthesis occurs when plants convert carbon dioxide from the atmosphere into organic compounds using energy from sunlight. Plants use these organic compounds – carbohydrates, proteins and lipids – to grow.

When the moss photosynthesises it releases some of these organic compounds into the soil which contains symbiotic bacteria. ̽��ֱ��bacteria break down the compounds, which they need to survive, liberating by-products that include electrons. ̽��ֱ��table designed by the Cambridge ̽��ֱ�� team captures these electrons to produce an electrical current.

̽��ֱ��table is based on research into biophotovoltaics funded by the Engineering and Physical Sciences Research Council (EPSRC). This pioneering work involves collaboration between the Departments of Chemical Engineering and Biotechnology, Biochemistry and Plant Sciences at Cambridge ̽��ֱ��, and the Chemistry Department at Bath ̽��ֱ��. ̽��ֱ��research is led jointly byDr Adrain Fisher, Professor Christopher Howe and Professor Alison Smith at Cambridge, and Dr Petra Cameron at Bath.

Carlos Peralta said: “ ̽��ֱ��moss table provides us with a vision of the future. It suggests a world in which self-sustaining organic-synthetic hybrid objects surround us, and supply us with our daily needs in a clean and environmentally friendly manner.”

Looking into the future, possible applications for BPV include solar panels, power stations and generators. Currently at concept stage, these are envisaged as sustainable solutions to pressing problems across the world – including the growing need for energy and fresh water from vulnerable communities.

“A modular system of biological solar panels would be mounted on to the roof of a building to supply it with a portion of its energy requirements,” explained Alex Driver “A biophotovoltaic power station would comprise giant algae-coated lily-pads floating on the surface of the ocean near the coastline, generating energy for local communities. A biophotovoltaic generator would feature algae solar collectors mounted on floating buoys and anchored just offshore to generate energy and harvest desalinated water, which is a waste product of one of the chemical reactions occurring in the device.”

̽��ֱ��Cambridge team emphasised that the technology was at very early stages. “It will be a long time before a product powered by this technology will be commercially available,” said Dr James Moutrie, Head of the Design Management Group at the Institute for Manufacturing. “ ̽��ֱ��table we are exhibiting this week demonstrates the ways in which designers can play a valuable role in early stage scientific research by identifying commercial potential and is one of the outcomes from our Design in Science research project.”

Scientists at Cambridge ̽��ֱ�� are exhibiting a prototype table that demonstrates how biological fuel cells can harness energy from plants.

̽��ֱ��moss table provides us with a vision of the future. It suggests a world in which self-sustaining organic-synthetic hybrid objects surround us, and supply us with our daily needs in a clean and environmentally friendly manner.

Carlos Peralta

Institute for Manufacturing, ̽��ֱ�� of Cambridge

Close-up of the moss pots incorporated into a novel table developed at Cambridge ̽��ֱ��.

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