Energy and Environmental Engineering

Solar, wind and other renewable energy notably vary with season and time of day and susceptible to fluctuating weather patterns. Effective use of renewable energy requires integrated design of energy flows to meet supply-demand balance in industrial areas and urban districts. In addition, stable and low-cost energy carriers as well as chemical storage of these renewable energies are also extremely important. We are developing comprehensive technologies towards carbon neutrality as follows: hydrogen production/storage using renewable energy, efficient combustion of carbon-neutral fuels and chemical-thermal storage that saves energy by utilizing exhaust heat in factories via efficient recovery, transport, and reuse cycle.

Core Technologies

Catalyst and Resource Chemical Process, Chemical Reaction and Process System Engineering, Thermal Engineering, Fluid Engineering, Fundamental Physical Chemistry, Functional Solid State Chemistry, Energy Chemistry, Sound Material-Cycle Social Systems, Social Systems Engineering

Artificial Photosynthesis

Artificial photosynthesis converts CO2 to organic substances using only H2O and sunlight, and hence enables the recycle of emitted CO2. We have established an artificial photosynthesis technology that continuously produces formic acid –an organic substance– from CO2 dissolved in an electrolyte at normal temperature and pressure. We constructed a 1 m2-sized artificial photosynthetic cell, and demonstrated a solarto- chemical conversion efficiency of 10.5% that is the world record for large sized cells. We employed the combination of crystalline silicon solar cells and an electrochemical reactor loading original catalyst, and then optimized the electron transport and electrolyte flow to achieve both a practically large size and a high efficiency.

Artificial photosynthesis reaction system (top) View of a one-meter square electrode and an artificial photosynthetic reaction (bubbles are generated oxygen) (bottom)

Ammonia Combustion

Ammonia can be synthesized from hydrogen by using renewable energy. While it has the advantages of easy liquefaction and higher energy density compared to hydrogen, it is difficult to burn. Our work enables to start the gas turbine with the single ammonia fuel by using a reformer. In addition, we constructed a CO2-free gas turbine combustion technology that enables the stable combustion even when liquid ammonia is directly supplied during the power generation operation*.
*Jointly developed with Toyota Motor Corporation and the National Institute of Advanced Industrial Science and Technology (AIST)

CO2-free gas turbine combustion technology overview and view of full-ammonia combustion