Sunlight is a widely available source of energy that is inherently bound to the daily and seasonal cycles. In Finland, solar power is excessively abundant in the summer when the need for energy is low. The opposite is true in the winter; when the demand for energy is high, the amount of solar power is scarce. This seasonal variation highlights the need to establish efficient ways to store the energy provided by light.
Organic compounds are an excellent form for energy storage due to their high energy density. In a pursuit for sustainable production of reduced carbon compounds, there is a strong interest in efficient utilization of carbon dioxide (CO2). Current industrial methods to reduce CO2 into fuels and chemicals are algal biofuels, Fischer-Tropsch synthesis, and electromethanogenesis. The aim of the OPTOBIO project funded by the Academy of Finland New energy program is to increase the efficiency of light and CO2 conversion to a specific fuel component through the integration of non-biological and biological systems. This will be achieved by developing novel optoelectronic and nanostructured materials and integrating them with microbial cells in a hybrid process for efficient conversion of light energy to microbially produced transport fuels.
Synthetic light harvesting systems based on optoelectronics possess the potential to increase the overall light harvesting efficiency
i)by providing a complementary absorption spectrum compared to natural phototrophic organisms
ii)by removing ultraviolet light that is harmful for microbes
iii)by converting some of the light to electricity or hydrogen
iv)by using nanoscale structures as electron guides and for better immobilization of microbes
v)by photoelectrochemical reduction of CO2 to compounds that are suitable as auxiliary carbon feeds for microbes.
The established systems will offer means for the CO2 utilization in novel types of bioreactors for biofuel production. In the future, such bioreactors could serve especially as decentralized energy conversion systems.
The OPTOBIO project is a collaboration between the Aalto University and VTT Technical Research Centre of Finland Ltd and it uses multi- and interdisciplinary approaches in quantum optics, photonics, nanotechnology, nano- and microfabrication, bionanomaterials, synthetic biology, industrial biotechnology and a life cycle analysis (LCA). The LCA is done at the level of feasibility screening to guide technology developments and estimate which concepts can be matured to industrial relevance.
The project will work towards a functional hybrid system where non-living matter (light-harvesting polymer) will be combined with living organisms (e.g. light-utilizing and/or electron bacteria) in order to provide complementary energy from light. The project deals with a central future challenge in establishing sustainable systems for the replacement of fossil fuels and it strives to offer novel solutions for the future bioeconomy-driven societies.
Text: Jussi Jäntti