Representation of variable renewable energy sources in TIMER,an aggregated energy system simulation model

The power system is expected to play an important role in climate change mitigation. Variable renewable energy (VRE) sources, such as wind and solar power, are currently showing rapid growth rates in power systems worldwide, and could also be important in future mitigation strategies. It is therefore important that the electricity sector and the integration of VRE are correctly represented in energy models. This paper presents an improved methodology for representing the electricity sector in the long-term energy simulation model TIMER using a heuristic approach to find cost optimal paths given system requirements and scenario assumptions. Regional residual load duration curves have been included to simulate curtailments, storage use, backup requirements and system load factor decline as the VRE share increases. The results show that for the USA and Western Europe at lower VRE penetration levels, backup costs form the major VRE cost markup. When solar power supplies more than 30% of the electricity demand, the costs of storage and energy curtailments become increasingly important. Storage and curtailments have less influence on wind power cost markups in these regions, as wind power supply is better correlated with electricity demand. Mitigation scenarios show an increasing VRE share in the electricity mix implying also increasing contribution of VRE for peak and mid load capacity. In the current scenarios, this can be achieved by at the same time installing less capital intensive gas fired power plants. Sensitivity analysis showed that greenhouse gas emissions from the electricity sector in the updated model are particularly sensitive to the availability of carbon capture and storage (CCS) and nuclear power and the costs of VRE.     

Utilization of cross-regional interconnector and pumped hydro energy storage for further introduction of solar PV in Japan

The amount of solar PV installed capacity has steadily increased to 44.5 GW at the end of FY2017, since the introduction of the Feed in Tariff (FiT) to Japan in 2012. On the other hand, since the first curtailment of solar PV was conducted on October 13th, 2018 in the Kyushu area, the curtailment has been frequently executed including wind power after that. In this study, cross-regional interconnector and pumped hydro energy storage (PHES) are focused on mitigating curtailment.In Japan, there are 9 electric power areas which connected each other by cross-regional interconnectors. According to the historical operation, cross-regional interconnectors were secured as emergency flexible measures, but after the implicit auction was started from October 2018, it is used on merit order. Regarding a PHES in Japan, they have been built with nuclear power plants for several decades. Because the output of nuclear power generation is constant, so the PHES is used to absorb the surplus at nighttime when the demand declines. All nuclear power plants in Japan have been shut down after the accident at the Fukushima Daiichi Nuclear Power Plant following the Great East Japan Earthquake that occurred on March 11th, 2011. There are several nuclear power plants that have been restarted (9 reactors, as of August 2019).In this study, the amount of curtailment for solar PV in the Kyushu area is sent to the Chugoku area using the cross-regional interconnector (Kanmon line). Then, the PHES in the Chugoku area is pumping with low price. Because the spot price in the market is low when the curtailment is executed. After that, the PHES is generating at night with high price when the solar PV is not generating. It makes a profit by the deference for the cost of pumping and the revenue of generating by the PHES. As a calculation result, for one week from May 2nd to 8th, 2019, a profit becomes 152.2 million JPY (about 1.22 million EUR). For this purpose, it is necessary to raise the operation capacity of the cross-regional interconnector up to the rated capacity with the frequency control function of solar PV instead of the capacity to keep frequency in the event of an accident. This will allow the further introduction of solar PV in Japan.     

A reduced-form approach for representing the impacts of wind and solar PV deployment on the structure and operation of the electricity system

In many climate change mitigation scenarios, integrated assessment models of the energy and climate systems rely heavily on renewable energy technologies with variable and uncertain generation, such as wind and solar PV, to achieve substantial decarbonization of the electricity sector. However, these models often include very little temporal resolution and thus have difficulty in representing the integration costs that arise from mismatches between electricity supply and demand. The global integrated assessment model, MESSAGE, has been updated to explicitly model the trade-offs between variable renewable energy (VRE) deployment and its impacts on the electricity system, including the implications for electricity curtailment, backup capacity, and system flexibility. These impacts have been parameterized using a reduced-form approach, which allows VRE integration impacts to be quantified on a regional basis. In addition, thermoelectric technologies were updated to include two modes of operation, baseload and flexible, to better account for the cost, efficiency, and availability penalties associated with flexible operation. In this paper, the modeling approach used in MESSAGE is explained and the implications for VRE deployment in mitigation scenarios are assessed. Three important stylized facts associated with integrating high VRE shares are successfully reproduced by our modeling approach: (1) the significant reduction in the utilization of non-VRE power plants; (2) the diminishing role for traditional baseload generators, such as nuclear and coal, and the transition to more flexible technologies; and (3) the importance of electricity storage and hydrogen electrolysis in facilitating the deployment of VRE.     

Techno-economic review of existing and new pumped hydro energy storage plant

There has been a renewed commercial and technical interest in pumped hydro energy storage (PHES) recently with the advent of increased variable renewable energy generation and the development of liberalized electricity markets. During the next 8 years over 7 GW of PHES capacity will be added to the European network while projects are also planned in the USA and Japan. This paper provides a review of existing and proposed PHES plant and discusses the technical and economic drivers for these developments. Current trends for new PHES development generally show that developers operating in liberalized markets are tending to repower, enhance projects or build ‘pump-back’ PHES rather than traditional ‘pure pumped storage’. Capital costs per kW for proposed PHES in the review region range between €470/kW and €2170/kW, however these costs are highly site and project specific. An emergence has also been observed in recent PHES developments of the use of variable speed technology. This technology, while incurring slightly higher capital costs, offers a greater range of operational flexibility and efficiency over conventional PHES. This paper has primarily been prompted by a lack of detailed information on PHES facilities worldwide and reviews current developments in the context of market and generation mix changes. The most recent large scale review of PHES faculties was undertaken by the American Society of Civil Engineers Hydro Power Task Committee on Pumped Storage in 1996. In the absence of data in the literature on new PHES plant development, this review draws primarily on publicly available information from utilities, government bodies and electricity regulators. In the same context this study is limited to a review region of the European Union, Japan and the United States as information on developments outside these areas is difficult to procure. This paper also gives a review of locations and proposed timelines for new PHES development and provides a thorough up-to-date overview of the development trends of this technology.     

A review on the pattern of electricity generation and emission in Indonesia from 1987 to 2009

The level of energy demand plays a fundamental role in today's society. It is a vital input in supporting the physical and social development of a country, as well as national economic growth. Looking at the energy demand scenario in present time, the global energy consumption is likely to grow faster than the population growth across the world. Like any other energy sectors, electricity demand has significantly increased in Indonesia over the past years. Currently, there are six types of power plants in the country. The main sources of electrical energy are generated using the gas turbines, steam turbines, combined cycles, geothermal, diesel engine and hydro-powers. Most of Indonesia's power plants are using fossil fuel for electricity generation. Substantial growth in domestic energy demand, however, would be a major challenge for Indonesia's energy supply sector in the future. Over the past decade, thermal power plants generated about 86.69% of electricity and about 13.31% was generated by renewable energy such as hydro-power and geothermal in 2009. The purpose of this study is to chronicle and show a clear view of 23 years trend of Indonesia's electricity generation industry. Furthermore, the capacity of power generation installed and electricity generation from 1987 to 2009 has been gathered for this study. The total pollutant emissions and emission per unit electricity generation for each type of power plants have been also calculated using emission factors. Also, the pattern of electricity generation and emission has been presented. The results show that the implementation and contribution of combined cycle power plants should be increased together with renewable energy and natural gas which are recommended to reduce greenhouse gas emission.     

Asian international grid connection and potentiality of DC superconducting power transmission

In 2011, a large scale earthquake and tsunami hit the northeastern coast of Japan, and nuclear plants were damaged to a large extent. Before the Tsunami, 54 nuclear plants were operated, however presently, only three nuclear plants are in operation. Therefore, Japan is suffering from high price of electricity and low supply reliability. In generation mix, nuclear plants generate only one percent and 87 percent of electricity is generated by fossil energy. This is not preferable for Japan from the viewpoints of energy security and stable electricity supply. Therefore, it is mandatory to increase sustainable energy and to decrease consumption of fossil fuel. International grid connection and the Global Energy Interconnection will be one of countermeasures against these problems existing in Japan. In this paper, international grid connection initiatives proposed in Asia are described and features and issues of electric power grids in Japan are discussed to implement the international grid connection. As the key technology for implementing the international grid connection, the present status of DC superconducting power transmission lines and power converters for long-distance power transmission lines are presented. In conclusion, conditions and legal frameworks for realizing the international grid connection are described.     

Review of Japan's power generation scenarios in light of the Fukushima nuclear accident

Following on from the Fukushima Daiichi nuclear power plant accident, the Japanese government is now in the throes of reviewing its power policy. Under continuing policies of economic revival and greenhouse gas reduction, it is crucial to consider scenarios for the country to realize reliable, low‐carbon, and economic electricity systems in the future. On the other hand, the social acceptance of nuclear power will affect the final political decision significantly. Therefore, in the present study, proposed power generation scenarios in Japan in light of the Fukushima accident were reviewed comprehensively from economic, environmental, technological, resource, security, and social perspectives. The review concludes that in Japan, (i) renewable energy mainly solar and wind needs to be developed as fast as possible subject to various constraints, (ii) more gas power plants will be used to absorb the fluctuations of intermittent renewable energy and supply electricity gap, (iii) nuclear power will be reduced in the future, but a 0% nuclear power scenario by 2030 is unlikely to be a reasonable choice on most measures and (iv) the effective communication with the public is vital important. Copyright © 2014 John Wiley & Sons, Ltd.     

Renewable electricity in Sweden: an analysis of policy and regulations

This study aims to analyse the developments in renewable energy policy making in Sweden. It assesses the energy policy context, changes in the choice of policy instruments, and provides explanations behind policy successes and failures. Swedish renewable energy policy has been developing in a context of uncertainty around nuclear issues. While there has been made a political decision to replace nuclear power with renewables, there is a lack of consensus about the pace of phasing out nuclear power due to perceived negative impacts on industrial competitiveness. Such uncertainty had an effect in the formulation of renewable energy policy. Biomass and wind power are the main options for renewable electricity production. Throughout 1990s, the combined effect of different policy instruments has stimulated the growth of these two renewable sources. Yet, both biomass and wind power are still a minor contributor in the total electricity generation. Lack of strong government commitment due to uncertainty around nuclear issues is a crucial factor. Short-term subsidies have been preferred rather than open-ended subsidy mechanisms, causing intervals without subsidies and interruption to development. Other factors are such as lack of incentives from the major electricity companies and administrative obstacles. The taxation system has been successful in fostering an expansion of biomass for heating but hindered a similar development in the electricity sector. The quota system adopted in 2003 is expected to create high demand on biomass but does not favour wind power. The renewable energy aims are unlikely to be changed. Yet, the future development of renewable energy policies especially for high-cost technologies will again depend strongly on nuclear policies, which are still unstable and might affect the pace of renewable energy development.     

Investigating the need of nuclear power plants for sustainable energy in Iran

Over the decades, the consumption of all types of energy such as electricity increased rapidly in Iran. Therefore, the government decided to redevelop its nuclear program to meet the rising electricity demand and decrease consumption of fossil fuels. In this paper, the effect of this policy in four major aspects of energy sustainability in the country, including energy price, environmental issues, energy demand and energy security have been verified. To investigate the relative cost of electricity generated in each alternative generator, the simple levelized electricity cost was selected as a method. The results show that electricity cost in fossil fuel power plants presumably will be cheaper than nuclear. Although the usage of nuclear reactor to generate power is capable of decreasing hazardous emissions into the environment, there are many other effective policies and technologies that can be implemented. Energy demand growth in the country is very high; neither nuclear nor fossil fuel cannot currently cope with the growth. So, the only solution is rationalizing energy demand by price amendment and encouraging energy efficiency. The major threats of energy security in Iran are high energy consumption growth and economic dependency on crude oil export. Though nuclear energy including its fuel cycle is Iran's assured right, constructing more nuclear power plants will not resolve the energy sustainability problems. In fact, it may be the catalyst for deterioration since it will divert capital and other finite resources from top priority and economic projects such as energy efficiency, high technology development and energy resources management.     

Effects of nuclear power plant shutdowns on electricity consumption and greenhouse gas emissions after the Tohoku Earthquake

This study analyzes how the substitution of fossil fuels for nuclear power due to the shutdown of nuclear power plants after the Tohoku Earthquake affects electricity consumption and greenhouse gas emissions in Japan. Results indicate that Japan generated 4.3 million metric tons (or 0.3%, with a 95% confidence interval) of additional CO₂ emissions in 2011 following the earthquake. The increase in CO₂ emissions stemmed from the combined effects of decreased electricity consumption due to energy conservation efforts and the substitution of fossil fuels for nuclear power following the Tohoku Earthquake. Results also show considerable spatial variation in the impacts of the earthquake on net CO₂ emissions. A majority of the prefectures (40 of 47 prefectures, or 85%) were predicted to experience higher CO₂ emissions after the Tohoku Earthquake while the remaining (7 prefectures) were predicted to experience lower CO₂ emissions. Our findings suggest that Japan and countries under similar risks may want to reformulate energy policy by emphasizing utilization of diverse power and energy sources, including more renewable energy production and electricity conservation. The policy reform should also consider spatial variation in the combined effects of reduced reliance on nuclear power and increased CO₂ conversion factors.     

Governmental policy and prospect in electricity production from renewables in Lithuania

In Lithuania, the generation of electricity is based on the nuclear energy and on the fossil fuels. After the decommissioning of Ignalina nuclear power plant in 2009, the Lithuanian Power Plant and other thermal plants will become the major sources of electricity. Consequently, the Lithuanian power sector must focus on the implementation of renewable energy projects, penetration of new technologies and on consideration of the future opportunities for renewables, and Government policy for promoting this kind of energy. Production of electricity from renewable energy is based on hydro, biomass and wind energy resources in Lithuania. Due to the typical climatic condition in Lithuania the solar photovoltaics and geothermal energy are not used for power sector. Moreover, the further development of hydropower plants is limited by environmental restrictions, therefore priority is given to wind energy development and installation of new biomass power plants. According to the requirements set out in the Directive 2001/77/EC of the European Parliament and of the Council of 27 September 2001 on the promotion of electricity produced from renewable energy sources in the internal electricity market [Official Journal L283, 33–40, 27 October 2001], 7% of gross consumption of electricity will be generated from renewable energy by 2010 in Lithuania. The aim of this paper is to show the estimation of the maximum renewable power penetration in the Lithuanian electricity sector and possible environmental impact.     

福岛核危机后日本新能源格局的转变及其影响与启示

日本新能源的发展趋势会对全球的能源变革产生巨大作用。从第一次石油危机至今,日本的新能源无论是总量还是在能源结构中所占的份额都有了质的飞跃,这不仅是因为新能源的技术和设备有了长足进步,更重要的是来自日本政府能源政策的支持,但2011年的福岛核危机将彻底改变日本的能源格局。日本政府宣布将中止核电发展计划,可再生能源将成为下一步能源发展战略的核心。然而日本的规模化可再生能源过程也面临着如何弥补核电站退役后的电力缺口、国土面积狭小、电网网架薄弱以及因电价过高导致的巨额补贴费用等诸多困难。与此同时也给日本带来了新的发展机遇,可再生能源将成为日本经济新的增长点。日本核危机使全球核能遭遇低潮期,而可再生能源将迎来新的发展机遇,这有可能催生第三次产业革命。同时也认识到,能源来源的过于单一化使得能源风险加剧,需要建立健全的、快速的能源应急机制,加大国际间能源合作,突破能源技术壁垒。此次日本核危机促使中国反思自身的核电发展策略。中国具有丰富的可再生能源资源,当前应抓住这一发展机遇,加大产品技术含量,切勿盲目扩大生产规模,同时拓展非主流型可再生能源生产设备市场。政府要把握整体布局,避免出现区域性生产"过度"。     

Geographic aggregation and wind power output variance in Denmark

At modest penetration, wind power merely substitutes electricity generated typically at thermal power plants. In this case, wind power only provides economic benefits in terms of saved marginal fuel and operation and maintenance costs. At higher penetrations, it becomes increasingly important for the energy system to be able to operate without costly reserve capacity awaiting fluctuations in demand or wind power generation. Existing transmission interconnections have mainly been established in order to assist in reducing the reserve capacity of thermal power systems. While indeed relevant in thermal systems, this is typically even more important in renewable energy-based systems, in which fluctuations to a large extent are uncontrollable. This makes interconnected systems an interesting option for integrating electricity produced from such energy sources. Using a Danish example, this article demonstrates how different demand and wind production variations in different geographical areas assist in evening out fluctuations and reducing imbalances in systems with high penetrations of wind power. By exploiting these variations, the needs for reserve capacity and condensing mode power generation are reduced. However, the article also demonstrates that there are limits to what can be gained on this account.     

Techno – Economic assessment of flexible decarbonized hydrogen and power co-production based on natural gas dry reforming

The need for flexible power plants could increase in the future as variable renewable energy (VRE) share will increase in the power grid. These power plants could balance the increasing strain on electricity grids by renewables. The proposed plant in this paper can adapt to these ramps in electricity demand of the power grid by maintaining a constant feed and producing also high purity hydrogen. Dry methane reforming (DMR) is incorporated into a flexible power plant model and the key performance indicators are calculated from a techno-economic perspective. The net output of the plant is 450 MW with the possibility to lower power production and produce hydrogen, maintaining a high CO₂ capture rate (72%). Two cases are compared to the base case to quantify: (i) energy and cost penalties for CO₂ capture and (ii) advantages of flexible power plant operation. The levelized cost of electricity (LCOE) for the base case is 67 Euro/MWh, the addition of a carbon capture unit increases it to 82 Euro/MWh. In the case of flexible operation, both the LCOE and levelized cost of hydrogen (LCOH) are calculated and the two depend on the cost allocation factor. The LCOE ranges from 65 to 85 Euro/MWh while the LCOH from 0.15 to 0.073 Euro/Nm³. The DMR power plant presented in Cases 1 and 2 present little advantages in today's market conditions however, the flexible plant (Case 3) can be viable option in balancing VRE.     

A review on the pattern of electricity generation and emission in Iran from 1967 to 2008

The electricity consumption growth in Iran requires a rapid development of power plant construction. Like many other countries, most of the power plants in Iran are using fossil fuel. In the past decade, thermal power plants generated about 94% of electricity and about 6% was generated by renewable sources such as hydro-power. This study is to show a clear view of 42 years an evolutionary trend of Iran's electricity generation industry. The capacity of power generation installed and electricity generation from the years 1967 to 2008 has been gathered. The total pollutant emissions and emission per unit electricity generation for each type of power plants have also been calculated using emission factors and the pattern of electricity generation and emission has been presented. The results shown that encouraging of using renewable energy sources and increasing the contribution of the combined cycle as a best type of thermal power plants and use more natural gas is recommended to reduce emission.     

Turkey’s electricity generation problem and nuclear energy policy

Energy is undoubtedly the most key to sustainability of the economic growth of a country. Turkey is today dependent on energy approximately at a rate of 75%. The country is able to meet approximately half of its total electricity demand owing to its own limited resources. Over the past 10 years period, Turkey paid nearly half a trillion dollars for its energy bill. On the other hand, the official reserve assets are equal to 93 billion dollars in the central bank of Turkey in November 2018. New power plants are being installed and planned to decrease the energy dependency in the country, particularly for electricity generation. Of these plants, nuclear energy is currently one of the newest and the most debated issues for the country. Hence, this study mainly focused on the possible outputs of the transiting to nuclear energy such as carbon dioxide emissions, radiation doses, energy demand, economic growths, etc., in the country. Additionally, new shares on electricity generation by the new sources were foreseen with this study after the nuclear plants to be operated in Turkey.     

美国核能辩论现状与政策趋向分析

美国国内在是否利用核能发电这个问题上一直存在争议,拥核派和反核派的分歧主要是在核电成本是否高、核能是否安全以及核能是否属于清洁能源等方面。受日本核危机影响,美国核能辩论的重点转向核能安全,主要围绕核电站抵御自然灾害的能力、核废料储存、是否应该新建核电站以及延长现有核电站运营期限等问题展开。由于历次重大核事故后,新建核电站成本势必上升,加之美国各州新建核电站积极性不高,国际大环境也不利于拥核派,同时核能面临化石能源和可再生能源的激烈竞争,因此短期内美国核能开发步伐势必会放慢。但是从长期看,核能仍将是美国能源战略的重点之一,究其原因,发展核能是美国能源安全与经济发展的需要,也是应对气候变化的需要,另外,拥核派的积极游说和公关行动、反核派内部立场出现分化以及日本核危机的长期影响有限等也都是其原因之一。我国是世界上在建核反应堆数量最多的国家,但是围绕核能的公开辩论却很少,这不利于我国核能的开发。核能的辩论过程,也是核能知识普及的过程,只有对核能有深入全面的认识,才能减少对核能非理性的恐惧。我国绝不能因为一次核事故而改变战略方向,而应在吸取教训的基础上,在保证绝对安全的前提下,继续发展核能。     

A multi-model method to assess the value of power-to-gas using excess renewable

Power-to-Gas (P2G) is a process that produces a gas from electricity, which is most commonly hydrogen via electrolysis. While some studies have considered hydrogen as a power-to-power storage vector, it could also be used as a fuel across the energy system, for example for transport or heat generation. Here, two energy models are used to explore the potential contribution of P2G as a cost-effective source of hydrogen, particularly for future energy systems with high variable renewable energy (VRE) in which there are occasional periods when electricity supply exceeds demand. A detailed electricity system model is iterated with a multi-vector energy system model using a soft-linking approach. This iterative approach addresses shortcomings in each model to better understand the optimal capacity of P2G and the potential economic capture rate of excess VRE. The modelling method is applied to Great Britain in 2050 as a case study. A substantial proportion of excess VRE in 2050 can be captured by P2G, and it is economically competitive compared with alternative sources. Moreover, the effectiveness and economic viability of P2G for reducing excess renewable is robust at even very high levels of renewable penetration.     

Three options to calculate the percentage renewable energy: An example for a EU policy debate

The European Commission proposed a renewable energy directive with binding targets for the percentage renewable energy, usually calculated with the primary energy method. This method has the disadvantage that for hydro and wind electricity production is counted, whereas for thermal electricity the higher input to power plants is counted. Therefore, the Commission looked for an alternative: the final energy method. Also this method has disadvantages. Firstly, electricity consumption is weighed equally to fuel consumption for heat and transport, neglecting higher primary energy demand for electricity. Secondly, non-energy consumption of energy commodities is neglected, artificially raising the percentage renewable energy. Therefore, I introduce a simple substitution method, which measures renewable energy by comparison with hypothetical equivalent conventional energy. Calculations for EU-27 show that the method strongly affects the contributions of different sectors (electricity, heat and transport), sources and countries. Concluding, any credible calculation method should reflect the trade off between conventional and renewable primary energy. A simple substitution method fulfills this condition, contrary to the primary and final energy method. Using these biased methods may result in policies that are inefficient in terms of saving conventional fuels and avoiding CO₂ emissions, the main underlying goals of the proposed directive.     

Hydropower for sustainable water and energy development

Turkey has a total gross hydropower potential of 433 GWh/year, but only 125 GWh/year of the total hydroelectric potential of Turkey can be economically used. By the commissioning of new hydropower plants, which are under construction, 36% of the economically usable potential of the country would be tapped. Turkey presently has considerable renewable energy sources. The most important renewable sources are hydropower, biomass, geothermal, solar and wind. Turkey's geographical location has several advantages for extensive use of most of these renewable energy sources. Over the last two decades, global electricity production has more than doubled and electricity demand is rising rapidly around the world as economic development spreads to emerging economies. Not only has electricity demand increased significantly, it is the fastest growing end-use of energy. Therefore, technical, economic and environmental benefits of hydroelectric power make it an important contributor to the future world energy mix, particularly in the developing countries.