• Energy Research

Concern about global warming calls for an advanced approach for designing an energy system to reduce carbon emissions as well as to secure energy security for each country. Conventional energy systems tend to introduce different technologies with high conversion efficiency, leading to a higher average efficiency. Advanced energy systems can be achieved not by an aggregate form of conversion technologies but by an innovative system design itself. The concept of LCS (low carbon society) is a unique approach having multi-dimensional considerations such as social, economic and environmental dimensions. The LCS aims at an extensive restructuring of worldwide energy supply/demand network system by not only replacing the conventional parts with the new ones, but also integrating all the necessary components and designing absolutely different energy networks. As a core tool for the LCS design, energy-economic models are applied to show feasible solutions in future with alternatives such as renewable resources, combined heat and power, and smart grid operations. Models can introduce changes in energy markets, technology learning in capacity, and penetration of innovative technologies, leading to an optimum system configuration under priority settings. The paper describes recent trials of energy models application related to waste-to-energy, clean coal, transportation and rural development. Although the modelling approach is still under investigation, the output clearly shows possible options having variety of technologies and linkages between supply and demand sides. Design of the LCS means an energy systems design with the modelling approach, which gives solution for complex systems, choices among technologies, technology feasibility, R&D targets, and what we need to start.

Abstract This study estimates the global energy potential of solar photovoltaics and onshore wind power and characterizes it with respect to the proximity to urban areas. Solar and wind power are centerpieces of a decarbonized energy system, and that different to other energy resources are disperse and widely available across the world. Therefore, characterizing how close or far these resources can improve the estimation of their availability. The analysis is based on a model using geo-referenced data and parameters related to the energy resources, technologies and land features. Results showed that the energy potential of solar (409 PWh yr−1) and wind (354 PWh yr−1) energies concentrates in the vicinity of urban areas, demonstrating the value of resources close to urban areas for covering current electricity needs. For example, current electricity consumption can be covered with high-grade solar resources (capacity factor >24%) within 30 km away from urban areas, or with middle-grade onshore wind resources (capacity factor >20%) within 20 km away from urban areas. Thus, it suggests that constraining the use of solar and wind energy in the proximity of urban areas due to social acceptability concerns, may significantly impact the deployment of high to mid-quality resources. The study is a starting point to evaluate the effect of restrictions and costs related to the proximity on the availability of renewable resources and their penetration in long-term decarbonization scenarios.

Abstract The curtailment and storage associated with the fluctuation of electricity supplied by variable renewable energy (VRE) may limit its penetration into electricity systems. Therefore, these factors need to be explicitly treated in the integrated assessment models (IAMs). This study improves the representation of curtailment and storage of VRE in a computable general equilibrium (CGE) model. With the data generated from an hourly power sector model, curtailment and storage of VRE electricity are treated as a function of the shares of solar and wind in the electricity mix. This relationship is incorporated into a CGE model and we also updated the VRE costs and resource potential. The results show that with such improvement, by 2100, in a 450 ppm atmospheric CO 2 equivalent concentration (henceforth ppm) scenario, some electricity generated from VRE is either curtailed (2.1%) or needs to be stored (2.9%). In contrast, if VRE fluctuation is not considered, the long-term global economic cost of carbon mitigation is significantly underestimated (by 52%) in the same scenario. Conversely, updating the VRE costs and resource potential leads to a decrease in mitigation costs. Our simulation implies that the fluctuation of VRE cannot be ignored and needs to be incorporated into CGE models. Moreover, in addition to storage with batteries, many other options are available to reduce curtailment of VRE. The top-down type CGE model has limitations to fully incorporate all aspects due to its limited spatial, temporal, and technological resolution.

Abstract Rising concern about the effect of greenhouse gas (GHG) emissions on climate change is pushing national governments and the international community to achieve sustainable development in an economy that is less dependent on carbon emitting activities – a vision that is usually termed a “low-carbon society” (LCS). Since the utilization of energy resources is the main source of GHG emissions, restructuring current energy systems in order to incorporate low-carbon energy technologies is essential for the realization of the LCS vision. Energy policies promoting the penetration of these technologies must view the role of energy in society as a system, composed of several energy resources, conversion technologies and energy demand sectors. The feasibility of the LCS in the future can be better understood by means of energy models. Energy models are valuable mathematical tools based on the systems approach. They have been applied to aid decision-making in energy planning, to analyze energy policies and to analyze the implications arising from the introduction of technologies. The design of the LCS requires innovative energy systems considering a trans-disciplinary approach that integrates multi-dimensional elements, related to social, economic, and environmental aspects. This paper reviews the application of energy models considering scenarios towards an LCS under the energy systems approach. The models reviewed consider the utilization of waste for energy, the penetration of clean coal technologies, transportation sector models as a sample of sectoral approaches, and models related to energy-for-development issues in rural areas of developing countries.

Abstract Decarbonization of global energy supply requires among others the development and deployment of unconventional energy technologies, which can overcome certain barriers to the deployment of conventional technologies. In addition, it is necessary to clarify the amount of energy that can be potentially produced from these novel technologies. This study presents a global assessment of the energy potential of an unconventional wind energy technology called airborne wind energy system (AWES) for onshore applications. This technology has a considerably small material footprint and visual impact compared to the conventional wind turbines. The target technology is a system currently available in the market that generates electricity based on a soft kite connected by a tether to a generator. It was found that globally, this technology can theoretically deliver 38.5 PWh yr−1. After considering topographic and land suitability restrictions the energy potential decreases to 12.5 PWh yr−1 (equivalent to around half of 2022 electricity consumption). The high-grade energy potential (annual average capacity factor >32%) constituted around three quarters of the global total. Further analyses will clarify the effect of uncertainties involved in the assessment (such as the height of operation and the land suitability constraints, among others), and the conditions under which AWES outperform conventional wind turbines. Also, the assessment can be extended to offshore applications and to include the economic evaluation of the energy potential. This study is a first attempt to assess the global potential of an unconventional wind energy technology which can be considered in the analysis of future decarbonization scenarios.

AbstractJapan has set greenhouse gas emissions reduction targets for 2030 and 2050, as stated in the nationally determined contribution (NDC) and in the long-term strategy for decarbonization (LTS) submitted to the UNFCCC in 2020, respectively. While upgrading these targets is needed to realize the global climate goals (2 °C and 1.5 °C), the implications of the target for the period in-between remains unclear. This study assesses the energy and macroeconomic impacts of enhancing the ambition of 2040 and 2050 emission reduction targets in Japan by means of a computable general equilibrium (CGE) model. In addition, we analyze the implications on the speed of energy efficiency improvement and low-carbon energy penetration along with macroeconomic impacts, and the shift from the current LTS goal (80% emissions reduction by 2050) to a full decarbonization one. The study shows that, compared to the current ambition (53% reduction by 2040 compared to 2005), enhancing ambition of the 2040 (63% reduction by 2040 compared to 2005) and 2050 targets (zero emissions by 2050) rises the share of low-carbon energy supply more drastically than the decreases in energy intensity, and increases macroeconomic costs by 19–72%. Moreover, meeting these targets demands accelerating considerably the reductions in carbon intensities through expansion of renewables and CCS beyond historical trends and beyond current efforts towards the 2030s NDC. Enabling larger low-carbon supplies and energy efficiency improvements makes full decarbonization by 2050 possible at costs equivalent to current ambition. Further analyses are needed to clarify at a finer detail the implications of changes in these enablers by sectors, technologies and policies. This kind of analysis offer key insights on the feasibility of Japan’s emission reduction targets for the formulation of new commitments for the next cycle of the Global Stocktake under the Paris Agreement.

PurposeThis study aims to present preliminary results from an integrated evaluation of electricity supply systems for rural areas using renewable energy technologies by means of a multi‐objective decision making methodDesign/methodology/approachGoal programming is applied to obtain the optimal system configuration meeting the electricity demand, based on the location's resource availability and taking diesel generation as the alternative of reference. The performance of the system is evaluated through four attributes: electricity generation costs, employment and two environmental impacts (CO2 emissions and land use). The model is designed for isolated rural area belonging to the non‐interconnected zones of Colombia.FindingsApplication of the method showed that biomass conversion technology has the highest potential and that renewable energy systems offer better performance than diesel generation. Reductions of more than 10 percent in unit electricity costs, land use rates and CO2 emissions can be achieved.Research limitations/implicationsInclusion of additional attributes and sensitivity analysis are matters of future research.Originality/valueThe methodology used in this study is an alternative means to perform evaluation of electricity supply systems integrating several aspects of technology and which is flexible enough so as to enable the inclusion of a wider scope of interests towards energy access targets.

Abstract Decentralized electrification using local resources can reduce regional disparity in rural and remote areas in terms of supply reliability and cost, as well as promote income generation. In this research an optimization energy model is introduced for designing decentralized energy systems using biomass for rural electrification in developing countries. Regional disparity is incorporated disaggregating electricity demand into urban, rural and remote areas. The model has been applied for designing a decentralized system using agricultural waste and forest biomass in a region in Colombia, South America. The resulting design includes biomass technologies in remote areas, reducing supply cost by 30% in this region. Using agricultural waste for electricity generation increases unit costs by 25% and reduces 15% of CO2 emissions compared to the current energy system. Using all biomass to meet current demand lowers the efficiency of the system, resulting in high system costs and emissions reduction. Reduction of disparity in electricity access among regions using local biomass needs to balance the increase in energy system costs and CO2 emissions reduction. For instance, using 30% of available biomass reduces 22% of system CO2 emissions, and provides 121 USD/house/yr and 99 USD/house/yr of additional income in rural and remote areas, respectively. Design of the energy system considering regional disparity shows that fuel transportation costs and efficiencies of biomass conversion technologies have significant impact on system configuration and performance.

National-level climate actions will be vital in achieving global temperature goals in the coming decades. Near-term (2025–2030) plans are laid out in Nationally Determined Contributions; the next step is the submission of long-term strategies for 2050. At present, national scenarios underpinning long-term strategies are poorly coordinated and incompatible across countries, preventing assessment of individual nations’ climate policies. Here we present a systematic and standardized, yet flexible, scenario framework varying 2050 emissions to build long-term national energy and climate mitigation scenarios. Applying the framework to six major Asian countries reveals individual challenges in energy system transformation and investment needs in comparable scenarios. This framework could be a starting point for comprehensive assessments as input to the Global Stocktake over the coming years.