Advanced Bio-Photovoltaic Devices for Solar Energy Conversion

Lead Research Organisation: University of Cambridge
Department Name: Chemical Engineering and Biotechnology

Abstract

Rising atmospheric carbon dioxide levels, and concerns over energy security, mean that there is increasing interest in developing renewable energy technologies. Solar technologies are deemed to be particularly attractive, since over 100 000 TW of solar energy falls on the Earth every year. The human population currently use 10 TW of energy per annum, and by 2050, it is predicted that our energy demand will double to 20 TW per annum. It is therefore theoretically feasible that solar technologies could provide a significant proportion of our future energy requirement. However, harvesting a large proportion of this solar energy, in a cheap, efficient manner, poses many difficult technical challenges. At present, silicon based solar PV cells are the method of choice, but these devices tend to be very expensive to manufacture, since they contain highly purified, semi-conductive materials. In this application we propose to harness the photochemical reactions associated with photosynthesis, a fundamental biological process, to convert sunlight into a usable form of energy by means of a biological photovoltaic panel. Using a multidisciplinary consortium of groups based in Plant Science, Biochemistry, Genetics, Engineering and Chemistry we intend to develop, test and optimise biological photovoltaics for the production of hydrogen and/or electricity. A large amount of work has already been carried out in the field of biological hydrogen production, but so far it has proved difficult to overcome the major technical hurdle that limits the commercialisation of this technology, namely that the oxygen produced during photosynthesis inhibits the production of hydrogen from the hydrogenase enzyme in vivo. Although there has been some interest in fabricating artificial devices with purified protein complexes to overcome this problem, the instability of these proteins has prevented economic exploitation. In this application, we propose to separate the processes of oxygen evolution and hydrogen production in a semi-biological photovoltaic device using intact photosynthetic cells, in which protein complexes are intrinsically more stable, and which furthermore have mechanisms for self-repair. The device will be composed of two chambers, or half-cells, with oxygen evolution confined to one chamber and hydrogen production to the other. In addition, the approach can be used to produce a DC electrical current, in a manner analogous to standard silicon based photovoltaic panels.

Publications

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Inglesby AE (2013) In situ fluorescence and electrochemical monitoring of a photosynthetic microbial fuel cell. in Physical chemistry chemical physics : PCCP

 
Description In this project harnessing of the photochemical reactions from photosynthesis to convert natural sunlight into a usable form of energy by means of a biological photovoltaic panel is addressed. A multidisciplinary consortium is working on novel biological photovoltaic devices for the production of hydrogen and/or electricity. The programme utilises photolithographic methods to construct a range of two chamber ultra thin layer electrochemical reactors using algal or cyanobacteria substrates in the anodic chamber for light capture.



The programme findings include:

The development of a series of candidate reactor designs optimised and tested with a variety of electrode materials to optimise the photoefficiency. Two main classes of device have been established, the first uses a redox mediator to shuttle electrons between biological substrate and the electrode. The second utilises a biofilm grown on the anodic chamber electrode for direct light capture and electron transfer to the electrode. Device performance has been characterised electrochemically using voltammetric methods and advanced impedance analysis. The results from the electrical analysis has been used to optimise photoefficiencies from the devices and also to improve losses due to factors such as internal resistance or mass transfer limitations, etc.
Exploitation Route The biological photovoltaic consortium have developed a range of demonstrator devices for public engagement activities. The devices utilise a variety of biological substrates, eg algae, moss, which are grown in the anodic chamber of an electrochemical cell. These anodes are utilised with a traditional cathodic chamber to create an electrical device which can generate an electrical voltage and current. Demonstrators developed have been used in a range of different public events, including, a Royal Society Summer of Science Exhibition, The London Design Festival and Salon Satellite, in Milan. The research carried out in the programme will be exploited in the recently announced Cambridge centre for Carbon Reduction in Chemical Technology (C4T) on the CREATE campus in Singapore. The biological photovoltaic programme will form one element of this centre's activity under the direction of Dr Fisher, one of the principal investigators for the Cambridge centre.
Sectors Energy

Environment

 
Description The longterm target for BPV research is the production of an economical device with low manufacturing costs and competitive energy conversion efficiencies. Although BPV cells may be destined to remain less efficient than traditional semiconductor PVs, the biological advantages, such as renewability and ability for self-repair, may lead to BPV systems becoming a viable alternative energy resource. These ideas have led to scientists in the BPV consortium to take part in a collaborative project at the University of Malaysia
First Year Of Impact 2011
Sector Education
Impact Types Societal

 
Description Research Collaboration with NTU Singapore 
Organisation Nanyang Technological University
Department School of Chemical and Biomedical Engineering
Country Singapore 
Sector Academic/University 
PI Contribution The project is currently exploring the application of biophotovoltaics towards waste water treatment. The cambridge team have supplied technical know how and supported reactor development.
Collaborator Contribution Collaborative partners at Nanyang Technological University are exploring biological manipulation of candidate cyanobacteria and algae, to further understand the underlying mechanisms associated with the bpv devices and also to potentially improve overall efficiency.
Impact This work is at an early stage and will involve, biochemists, chemists and chemical engineers
Start Year 2016
 
Title Thin layer microengineered bio-photovoltaic devices 
Description To explore the influence of device geometry on the electrical efficiency of a bio-photovoltaic cell, microfabricated reactors with precise anode-cathode electrode separations were constructed. These prototypes provided preliminary indications of optimal reactor configuration and design of the bio-photovoltaic cells. 
Type Of Technology Physical Model/Kit