The Japanese government is seeking renewable sources of energy and has been interested in exploring the possibilities for importing renewable energy from overseas in a chemical form since the government aims at establishing a hydrogen-based society in Japan. The Japanese government target for reduction of global greenhouse gas emissions is 26% by 2030. And they are aiming to achieve the long-term goal of reducing global greenhouse gas emissions, 80% by 2050, while both implementing global warming prevention measures and sustaining economic growth.
Solar energy is, of course, the largest renewable energy source, and solar “thermal” energy is one of the promising renewable energy sources for massive scale production of solar hydrogen in sun-belt regions, such as the southwestern United State, MENA regions, Australia, etc. Solar hydrogen needs to be converted into transportable liquid fuels, such as methanol, liquid hydrogen, ammonia or methylcyclohexane (MCH). Thus, many companies and R&D organizations are interested in developing concepts/techniques to ship hydrogen in the form of transportable carrier to Japan. Chiyoda Corporation is developing a hydrogen supply chain concept using MCH. In that concept, hydrogen is converted to MCH using toluene since it is easier (than hydrogen) to transport into Japan. MCH is then converted into toluene by releasing three hydrogen molecules for every MCH molecule. The toluene is then shipped back to the hydrogen production site for conversion to MCH. A project was recently started to demonstrate this concept (by December 2020) by transporting the hydrogen from Brunei (Borneo island) to Japan. In this project, liquefied natural gas (LNG) is used to produce hydrogen in Brunei. On the other hand, Kawasaki Heavy Industries Ltd. (KHI, Tokyo, Japan) is developing another concept to produce cost-effective hydrogen by coal gasification with CCS (using brown coal) in Australia and import into Japan through liquid hydrogen tankers. To demonstrate this concept, the Hydrogen Energy Supply Chain (HESC) project was started to ship the hydrogen from Victoria state, Australia to Japan. In other R&D activities, ammonia and methanol are also considered as promising hydrogen energy carriers.
In parallel with demonstrating some massive hydrogen supply chain concepts, the Japanese government is seeing technologies for massively and cost-effectively producing CO2 free hydrogen. Although hydrogen production using solar energy is more appropriate than CCS-combined coal gasification or NG reforming, the production cost is relatively expensive. According to Japanese government strategy, the target cost of hydrogen is ¥30/Nm3 by 2030 and ¥20/Nm3 by 2040 in Japan. At present, the actual production cost in Japan is around ¥100/Nm3. The government is planning to start importing 10 × 106 tons of hydrogen to Japan by 2040.
Solar thermochemical water splitting cycles have the potential to produce solar hydrogen around AUD $4– 6/kg of hydrogen (around ¥30 – 50/Nm3) by 2020 according to the solar thermochemical fuels production feasibility study conducted by CSIRO (Australia) a few years ago through Australian Renewable Energy Agency (ARENA) funded project. Furthermore, solar thermochemical hydrogen can be produced even much less than this cost through solar gasification of black or brown coal or solar reforming of NG. However, when including the hydrogen conversion (to energy carrier) and shipping cost (to Japan), the final cost of hydrogen in Japan exceeds the Japanese target cost. In order to reduce solar thermochemical fuels cost in a massive scale production, industries and academia need to collaborate in the research, development, and demonstration of solar thermochemical fuel production including hydrogen supply chain or carbon cycles. Then, there will be chances to reduce the solar thermochemical hydrogen cost extensively by 2040.