North-East Asian Super Grid for 100% renewable energy supply: Optimal mix of energy technologies for electricity, gas and heat supply options
Introduction
Fast economic growth in the North-East Asian region provoked an extensive rise in electricity demand, based mainly on fossil fuel utilization, in the last decades [1]. Increasing ecological and social problems are caused by the fossil fuel based energy system, including increased anthropogenic pressure on nature in general [2] and an ongoing destruction of ecosystems all around the world [3]. This anthropogenic pressure leads in particular to climate change [4], which will have a dramatic negative impact on the economy on a global scale, as concluded by Stern [5]. Harmful and costly consequences of coal-based air pollution [6] have to be further taken into account for the full societal cost of energy supply. These issues drive the idea for a renewable energy (RE) based system development up to 100% RE [7] and the discussion of its competitiveness on a global scale [8] and in a rather distributed manner [9]. It is feasible that RE based systems can decrease the anthropological footprint [10] in particular since the most important RE technologies show a continued strong growth and the large majority of countries in the world have introduced respective policies [11].
Scenarios of energy systems based on very high shares of RE had been already discussed for several countries and regions. Connolly and Mathiesen [12] showed for the case of Ireland in an hourly modeling that 100% RE is technically feasible and economic affordable. Henning and Palzer [13] discussed that a 100% RE system for the sectors electricity and heat is technically doable and the cost are comparable to the current energy system, also based on hourly resolution. Thellufsen and Lund [14] pointed out that energy efficiency measures in the electricity and heat sector can even generate positive synergies for 100% RE for the example of Denmark. Critz et al. [15] emphasized that demand response measures help to integrate a high penetration of renewables into the existing system and that it can reduce the overall cost for the case of Hawaii. Huber et al. [16] found on the case of the ASEAN region that a well balanced mix of renewable resources and a geographic integration of a larger region is required for balancing high shares of RE.
Komoto et al. [17] proposed very large scale solar photovoltaic power plants for North-East Asia pointing out that excellent renewable resources of a large unpopulated region, such as the Gobi desert, can be utilized for a very large region by applying a Super Grid approach. The availability of various types of RE resources in Asian regions, including solar, wind and hydro resources, enables that very promising vision of building a Super Grid connecting different regional energy resources to reach synergy effects and realise a 100% RE electricity supply [18]. The idea of a global Super Grid for power supply was already discussed some years ago [19], and attracted new attention by the RE-based Gobitec [20], the Gobi Super Grid project initiating a deeper cooperation of North-East Asian countries [21] and the North-East Asian Super Grid initiative as highlighted from the Korean perspective [22] influenced by the EU-MENA sustainable energy system analyses [23] and the Desertec Foundation vision of utilizing RE sources in North Africa and Middle East for the region, but also for exports to Europe [24]. However, an economical assessment and energy system optimization of the North-East Asian Super Grid have never been done before, and the economic and technical feasibility of such a project was questionable. An RE-based electrical supply system can become a major step toward a 100% renewable energy supply. Bridging technologies such as power-to-heat and heat storage [25] will convert electricity generation losses and electricity curtailment into valuable heat for residential and industrial needs. Power-to-Gas (PtG) technology based on water electrolysis, CO2 from air, and methanation reactors will provide renewable synthetic natural gas supply for a 100% renewable energy system as introduced in the field of energy system analyses by Sterner [26], finally also used for chemicals, fertilizers, other industries, transportation and other non-power sectors [27]. However, as discussed earlier, a cost competitive 100% RE system can only be reached in case of an optimal design and wise utilization of all available RE resources in order to reach a maximum synergy between various resources, in particular for the key pillars solar photovoltaic and wind energy [28], but also in combination with the major energy storage technologies [9] and in interconnecting different regions. In this work the design of a centralized regional energy system is discussed, where each sub-regional system is optimized to match regional RE conditions, electricity and gas demand with regards to other regional parameters. Grid interconnections reduce regional independence, however that dependence is limited in its impact by accounting for respective grid losses and grid costs. Finally, an optimized energy system is the result of balancing regional conditions and energy demands, impacts of prosumers, and other configurations such as electricity exchange with neighbouring regions. This work is based on results obtained earlier [29] but presents a more comprehensive model, taking into account more technologies, a broader energy demand and the impact of prosumers.
Section snippets
Materials and methods
The model for optimizing the energy system structure is composed of a set of power generation and storage technologies, respective installed capacities and different operation modes of these technologies. Energy system models can be divided into market and regulatory models. An example of an agent based market model can be found in [30]. In such an approach the final structure of the system and the operation modes depend on the market rules applied to the agents. However, the resulting system
Region subdivision and grid structure
The North-East Asian region is divided into 13 sub-regions: Mongolia, East and West Japan (with respect to 50/60 Hz AC grids utilization), South Korea, North Korea, China divided into eight sub-regions by State Grid Corporation of China [38]: Northeast, North, East, Central, South, Northwest China, Tibet and Uygur regions.
In this paper, five scenarios of energy system development options are discussed:
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region-wide energy systems, in which all the regions are independent (no HVDC grid
Main findings on the optimized energy system structure and costs
For all scenarios optimized electrical energy system configurations are derived and characterized by optimized installed capacities of RE electricity generation, storage and transmission for every modeled technology, leading to respective hourly electricity generation, storage charging and discharging, electricity export, import and curtailment. In Table 12 the average financial results of the different scenarios according to (4.1), (4.2), (4.3), (4.4), (4.5), (4.6), (4.7), (4.8), (4.9), (4.10)
Discussion
The installation of a HVDC transmission grid enables a significant decrease in cost of electricity in the RE-based system. The total levelized cost of electricity in the region decreased from 80.9 €/MW h for the region-wide open trade scenario to 71.5 €/MW h for the country-wide open trade scenario and 69.4 €/MW h for the area-wide open trade scenario. The total annualized cost of the system decreased from 799 b€ to 683 b€. The difference in total region electricity prices between country-wide and
Conclusion
Existing RE technologies can generate enough energy to cover all electricity demand for the year 2030 on a significantly lower price level of 69.4 €/MW hel, compared to non-renewable options. A further improved energy system robustness increases the cost by 23% to 85.6 €/MW hel, still lower in cost then non-renewable options. It is also possible to cover the gas demand of the industrial and transportation sectors with PtG technology, although for a gas price which is substantially higher than
Acknowledgements
The authors gratefully acknowledge the public financing of Tekes, the Finnish Funding Agency for Innovation, for the ‘Neo-Carbon Energy’ project under the number 40101/14. The authors would like to thank Michael Child for proofreading. Thanks to the anonymous reviewers for their valuable comments.
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