12:00 〜 12:15
[U10-06] Climate mitigation measures and costs for carbon neutrality
★Invited Papers
キーワード：気候変動緩和、エネルギーシステム、統合評価モデル
In order to achieve global mean temperature stabilization, carbon neutrality (CN) will be required. Climate mitigation costs are critical to achieve the emission reductions and vary widely for different emission reduction levels or by when the carbon neutrality is achieved, under different scenarios of improvements of technologies, under future different socioeconomic conditions, etc.
Achieving CN requires decarbonized energy supply basically, however, there can be lots of options. Energy saving is still important even for the CN. Social innovations including sharing and circular economy associated with digital transformation will be a key for the CN as well as energy savings of each technology. Renewable energy, nuclear power, and fossil fuels with CO2 capture and storage (CCS) are re-quired as primary energy sources, in principle. In Japan, because all of these energy sources have cost and potential constraints etc., hydrogen import from overseas would be also an important option. Hydrogen can be produced typically by renewables and fossil fuels with CCS. To increase more convenient uses of hydrogen, ammonia and synthetic fuels (synthetic methane and liquid fuels) synthesizing with nitrogen and carbon will play important roles.
Using a global energy systems model DNE21+ considering the above technological measures, the emission reduction measures for the CN by 2050 are analyzed. DNE21+ is a global model with consistencies across 54 countries and regions, and intertemporal years up to 2100.
Under the globally least cost measure for the 1.5 °C scenario, the 2050 emissions in Japan are estimated to be -63% compared to 2013. This is because there are larger potentials with smaller costs of CO2 removal technologies (CDR) in the world than in Japan. Particularly the regions and countries where large potentials of bioenergy, variable renewable energy (VRE), and CO2 geological storage exist could serve the opportunities of CDR such as bioenergy with CCS (BECCS) and direct air CO2 capture and storage (DACCS) cost-efficiently.
While recognizing the emissions reduction opportunities in overseas, the domestic emission reduction measures should be considered. Even for achieving the CN within Japan, DACCS will be an important measure. However, if CO2 storage potentials including the opportunities of transport of CO2 to overseas are limited, the contributions of DACCS are reduced and the roles of synthetic fuels will increase. Meanwhile, there are no feasible solutions for the 2050 CN in Japan for any assumed scenarios under the socioeconomic and other assumptions without DACCS. Although the cost reductions of VREs are assumed, the costs also increase as larger deployments of VRE, and wide ranges of costs are estimated for VREs accordingly. Thus, according to the estimations under the least cost of whole energy systems, combinations of deployments of several emissions reduction measures including DACCS and imports of hydrogen, ammonia and synthetic fuels can be estimated. As contrasted with primary energy, electricity generations increase compared to the current levels in almost all the scenarios. Electrification is an important option for the CN. However, only in the RE100% case, electrification cannot be observed due to considerable increase in electricity costs including the grid integration costs of VREs. Balanced energy sources for power generation will be important also for the CN.
CO2 marginal abatement cost is estimated to be 168 $/tCO2 in the globally least cost measure case for the 1.5 °C scenario. On the other hand, the cost is estimated to be much larger, i.e., 525 $/tCO2, in the standard scenario for the CN domestically. It is necessary to seek the opportunities to induce several technological and social innovations for the cost reduction. The estimated costs will help not only developing the climate change mitigation strategies toward the CN, but also the balanced measures between mitigation and adaptation.
Achieving CN requires decarbonized energy supply basically, however, there can be lots of options. Energy saving is still important even for the CN. Social innovations including sharing and circular economy associated with digital transformation will be a key for the CN as well as energy savings of each technology. Renewable energy, nuclear power, and fossil fuels with CO2 capture and storage (CCS) are re-quired as primary energy sources, in principle. In Japan, because all of these energy sources have cost and potential constraints etc., hydrogen import from overseas would be also an important option. Hydrogen can be produced typically by renewables and fossil fuels with CCS. To increase more convenient uses of hydrogen, ammonia and synthetic fuels (synthetic methane and liquid fuels) synthesizing with nitrogen and carbon will play important roles.
Using a global energy systems model DNE21+ considering the above technological measures, the emission reduction measures for the CN by 2050 are analyzed. DNE21+ is a global model with consistencies across 54 countries and regions, and intertemporal years up to 2100.
Under the globally least cost measure for the 1.5 °C scenario, the 2050 emissions in Japan are estimated to be -63% compared to 2013. This is because there are larger potentials with smaller costs of CO2 removal technologies (CDR) in the world than in Japan. Particularly the regions and countries where large potentials of bioenergy, variable renewable energy (VRE), and CO2 geological storage exist could serve the opportunities of CDR such as bioenergy with CCS (BECCS) and direct air CO2 capture and storage (DACCS) cost-efficiently.
While recognizing the emissions reduction opportunities in overseas, the domestic emission reduction measures should be considered. Even for achieving the CN within Japan, DACCS will be an important measure. However, if CO2 storage potentials including the opportunities of transport of CO2 to overseas are limited, the contributions of DACCS are reduced and the roles of synthetic fuels will increase. Meanwhile, there are no feasible solutions for the 2050 CN in Japan for any assumed scenarios under the socioeconomic and other assumptions without DACCS. Although the cost reductions of VREs are assumed, the costs also increase as larger deployments of VRE, and wide ranges of costs are estimated for VREs accordingly. Thus, according to the estimations under the least cost of whole energy systems, combinations of deployments of several emissions reduction measures including DACCS and imports of hydrogen, ammonia and synthetic fuels can be estimated. As contrasted with primary energy, electricity generations increase compared to the current levels in almost all the scenarios. Electrification is an important option for the CN. However, only in the RE100% case, electrification cannot be observed due to considerable increase in electricity costs including the grid integration costs of VREs. Balanced energy sources for power generation will be important also for the CN.
CO2 marginal abatement cost is estimated to be 168 $/tCO2 in the globally least cost measure case for the 1.5 °C scenario. On the other hand, the cost is estimated to be much larger, i.e., 525 $/tCO2, in the standard scenario for the CN domestically. It is necessary to seek the opportunities to induce several technological and social innovations for the cost reduction. The estimated costs will help not only developing the climate change mitigation strategies toward the CN, but also the balanced measures between mitigation and adaptation.