Renewable energy generation and storage are one of society's greatest needs. Many of renewable energy sources exist in different forms such as waste heat, sunlight, and even wastewater. As a result of such variety of forms, a development of a wide range of energy converting technologies is essential. For example, Li-ion batteries can reversely transform electricity to chemical energy. Moreover, microbial fuel cell and thermoelectric module can convert organic matter and heat into electricity. The overall efficiency of these technologies is largely governed by reaction and transport of energy carriers such as electrons, ions, and phonons. Thus, detailed characterization holds the key to improvement of device performance.

In particular, electrochemistry plays an important role in batteries and microbial fuel cells. However, the complexity of electrochemically-driven reactions often made it difficult to improve the efficiency of these systems and warrant fundamental understanding. Here, we develop synchrotron-based spectro-microscopy to investigate the detailed kinetics and thermodynamics of electrochemical reactions while they take place. In this talk, I will present new insights on three important classes of renewable energy technologies with novel characterization platform: (1) lithium insertion in lithium iron phosphate olivine battery electrodes (2) single-bacterium level charge transfer in microbial fuel cell (3) electron and phonon transport in silicon thermoelectrics.