This section groups EPFL’s research projects that get inspired by the way organisms use chemistry to produce and store energy. We explore how photosynthesis has perfected the capuring and transformation of solar energy, but also how existing microbial biochemistry could be used to produce biofuels.
Artificial photosynthesis strives to replicate natural photosynthesis, a process that converts sunlight to split water into oxygen and hydrogen. Hydrogen can further be combined with carbon dioxide to create fuels for human usage.
DSSC use surface-bound dyes, like the chlorophyll in green leaves, that DSSC use surface-bound dyes, like the chlorophyll in green leaves, that DSSC use surface-bound dyes, like the chlorophyll in green leaves, that DSSCDSSC use surface-bound dyes, like the chlorophyll in green leaves, that catch photons of incoming light and uses their energy to excite electrons. These electrons are further on passed to nanocrystalline titanium dioxide. Current research focuses on introducing revolutionary new concepts in the choice of the three materials that play a key role for performance and durability of the DSSC, i.e., the light harvesting pigment, the electrolyte or whole conductor and the mesoporous TiO2 scaffold. Our research output will pave the way to enhance the production and sales of a new generation of durable and highly efficient glass panels that meet the esthetic and high quality demand of the market.
The Solar Fuels subgroup at LPI is aimed at developing materials and processes for clean and renewable chemical fuel generation from sunlight, namely via water splitting to produce hydrogen or carbon dioxide reduction to form hydrocarbons. This employs the concept of photoelectrochemistry, encompassing the solid state physics of light absorption and charge separation, the electrochemistry of semiconductor/catalyst/liquid interfaces, and the chemical engineering of gas generation, electrolyte management, and cell design.
The SHINE-Nanotera project aims to develop a hydrogen production system using sunlight in an integrated manner with earth abundant materials mimicking natural photosynthesis. The project focuses on development of PhotoElectroChemical (PEC) systems that use semi-conductor materials to absorb photons from the sun to generate a potential high enough (>1.23 V) to split water and produce hydrogen and oxygen at an integrated electrolysis cell. A major advantage of PEC systems over systems composed of photovoltaic panels (PV) in conjunction to a separate electrolyzer is their integral approach, i.e. the PV cell is part of the electrolyzer. This provides opportunities not only for cost reduction but also for improvement in the efficiency of the electrochemical reaction. The project involves Michelin as an industrial partner, and its funded by the Nanotera.ch initiative.
The project leverages techniques in synthetic biology and protein engineering to engineer light-harvesting, biological constructs with enhanced synthetic activities; proteins and living cells are being “re-programmed” to behave like, and even interact with, synthetic devices. More info here
Solar cell nanowires inspired by forests
High efficiency solar cells rely on materials made of scarce earth elements. If not managed wisely the new energy limitations will come from the availability of these materials rather than the availability of the Sun. Prof. Anna Fontcuberta i Morral and her team have been tackling this issue by taking inspiration for the masters of the solar energy usage, the trees. They’ve specifically focused on the vertical structure of the trees that give them the capacity to capture the light around them even in a densely packed forest. So they’ve created a forest within the solar cells! This forest is made of nano scale filaments made of semiconducting materials, called nanowires that are vertically distributed within the solar cells. These forests of nanowires were able to capture 10 times more light than the standard, flat, solar panels while using 1 000 times less of scarce elements on the earth crust.
Hydrogen energy - Biomimetic synthesis of Fe-hydrogenase[Fe]-hydrogenase is a newly discovered hydrogenase that requires one single metal (Fe) for function. In light of the central role of H2 in technologies (fuel cell) and industries (hydrogenation), studies on the structure and function of [Fe]-hydrogenases are of significant current interest. Our group has developed two generations of synthetic models for the active site of [Fe]-hydrogenase, and has used them as structural and spectroscopic probes. Just recently, we have successfully synthesized a model complex that mimics faithfully the unusual pyridinyl methyl acyl moiety of the active site. The chemistry of this model complex provides an important chemical precedent for the enzymatic studies.
More information on the Lab page: http://lsci.epfl.ch/page-50523-en.html
Metabolic engineering for Ethanol production
In an effort of overcoming the limited availability of fossil energy resources the focus of the research and development in the area of biofuels has moved towards developing the second generation of fuels that should be produced via microbial fermentation. The idea is to use as a feedstock inexpensive and abundant waste materials such as lignocellulosic biomass. The second generation biofuels should satisfy several criteria such as lower emission, higher energy density and should be less corrosive to engines. The need for discovery of novel biosynthetic pathways towards desired molecules sparked the development of computational tools that are capable of reconstructing feasible reaction steps between a given set of starting compounds (precursors) and a molecule of interest (a target compound). In this study we have have reconstructed metabolic network for 69 fuel compounds, out of these we have taken 5 highest ranked for which we have created 1.8 million de novo pathways. These results demonstrate how TFA can also guide the selection of a suitable chassis organism. For all discovered reactions in the feasible pathways we have also identified known enzymes from the KEGG database with the closest reaction similarity that could be engineered for the implementation of novel reactions. This study shows the full potential of computational tools for discovery and design of novel synthetic pathways and their relevance for future developments in the area of metabolic engineering and synthetic biology.
For more information: https://infoscience.epfl.ch/record/219147?ln=en
Osmosis for electrical energy
We have developed a system that generates electricity from osmosis with unparalleled efficiency. Our work, featured in Nature, uses seawater, fresh water, and a new type of membrane just three atoms thick.
The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis. If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.
Video and full description HERE.
Nature article HERE
Biomass conversion to biofuels
Reducing our reliance on fossil fuels means turning to plant-derived biofuels and chemicals. But producing them cost-effectively from plants and other organic matter – collectively referred to as biomass – is a major engineering challenge. Most biomass comes in the form of non-edible plants like trees, grass, and algae, which contain sugars that can be fermented to produce fuel. But biomass also contains lignin, a bulky, complex organic polymer that fills wood, bark, and generally gives plants rigidity. Because it is difficult to process, lignin is usually discarded during biofuel processing. EPFL scientists have now turned lignin from a nuisance to an important source of biofuel by simply adding a common chemical, converting up to 80% of it into valuable molecules for biofuel and plastics. The patent-pending method, which can be scaled up to industrial levels, is published in Science.