Recent advances in ammonia synthesis technologies: Toward future zero carbon emissions

As a carbon-free molecule, ammonia has gained great global interest in being considered a significant future candidate for the transition toward renewable energy. Numerous applications of ammonia as a fuel have been developed for energy generation, heavy transportation, and clean, distributed energy storage. There is a clear global target to achieve a sustainable economy and carbon neutrality. Therefore, most of the research's efforts are concentrated on generating cost-effective renewable energy on a large scale rather than fossil fuels. However, storage and transportation are still roadblocks for these technologies, for example, hydrogen technologies. Ammonia could be replaced as a viable fuel for a clean and sustainable future of global energy. More efforts from governments and scientists can lead to making ammonia a clean energy vector in most energy applications. In this review, ammonia synthesis was assessed, including conventional Haber–Bosch technology. Current hydrogen technologies as the key parameters for ammonia generation are also evaluated. The role of ammonia as a hydrogen-based fuel and generation roadmap are discussed for future utilization of energy mix. Further, ammonia generation processes are addressed in depth, including blue and green ammonia generation. A survey of ammonia synthesis catalytic materials was conducted and the role of catalyst materials in ammonia generation was compared, which showed that the Ru-based catalyst generated the maximum ammonia after 20 h of starting experiment. An end-use plan for using ammonia as a clean energy fuel in vehicles, marines, gas turbines as well as fuel cells, is briefly discussed to recognize the potential applications of ammonia use. The practical and future end-use vision of energy sources is proposed to achieve great benefits at low carbon emissions and costs. This review can provide prospective knowledge of large-scale aspects and environmental considerations of ammonia. Herein, we conclude that ammonia will become the “clean energy carrier link” that will achieve the global energy and economy sustainability targets.     

Solar energy in India: Strategies, policies, perspectives and future potential

Renewable energy sources and technologies have potential to provide solutions to the longstanding energy problems being faced by the developing countries like India. Solar energy can be an important part of India's plan not only to add new capacity but also to increase energy security, address environmental concerns, and lead the massive market for renewable energy. Solar thermal electricity (STE) also known as concentrating solar power (CSP) are emerging renewable energy technologies and can be developed as future potential option for electricity generation in India. In this paper, efforts have been made to summarize the availability, current status, strategies, perspectives, promotion policies, major achievements and future potential of solar energy options in India.     

分布式供能技术的发展现状与展望

在能源结构调整中，分布式供能技术引起了世界能源界的广泛关注，在国家大电站和电网能基本保证供电的情况下，分布式供能和中央电站供能的结合，对于保障国家供应和经济的发展将发挥重要作用。对分布式供能、分布式电力、分布式能源资源的概念进行了详细的说明，指出分布式供能技术就是以一些小型发电设备技术进步为依托，以靠近用户侧建立小型电站为主，并结合热电（冷）联产等应用拓展为前提的整体供能系统。对于该技术发展的经济和社会动力进行了分析说明，对分布式供能技术的特点、应用领域、涉及的主要技术内容和具体特性进行了介绍，最后对其发展前景进行了展望。     

Concentrating solar power:Current status and perspective

太阳能热发电是将太阳能转化为热能,通过热功转化过程发电的技术.太阳能热发电站具有发电功率相对平稳可控,运行方式灵活,可进行热电并供等优势,同时具有非常好的环境效益.太阳能热发电规模化发展后,近期能够作为调峰电源为风力发电,光伏发电等间歇性电源提供辅助服务.随着未来技术的优化提升,由大型太阳能热发电站组成的太阳能热发电厂有可能承担电力系统基础负荷.目前,全球太阳能热发电产业正在兴起,装机容量逐年增加,然而,我国在太阳能热发电关键技术研究上明显落后于先进国家,太阳能热发电产业发展速度明显滞后;另外,我国也没有发布明确的太阳能热发电产业激励政策,这直接导致了一批项目迟迟不能落地.     

Techno-economic comparison of energy storage systems for island autonomous electrical networks

The oil-dependent electricity generation situation met in the Aegean Archipelago Islands is in great deal determined by increased rates of fuel consumption and analogous electricity production costs, this being also the case for other island autonomous electrical networks worldwide. Meanwhile, the contribution of renewable energy sources (RES) to the constant increase recorded in both the Aegean islands’ annual electricity generation and the corresponding peak load demand is very limited. To compensate the unfavorable situation encountered, the implementation of energy storage systems (ESS) that can both utilize the excess/rejected energy produced from RES plants and improve the operation of existing thermal power units is recommended. In the present study, a techno-economic comparison of various RES-ESS configurations supported by the supplementary or back-up use of existing thermal units is undertaken. From the results obtained, the shift of direction from the existing oil-dependent status to a RES-based alternative in collaboration with certain storage technologies entails – apart from the clear environmental benefits – financial advantages as well.     

Grid integrated renewable DG systems: A review of power quality challenges and state-of-the-art mitigation techniques

Increased energy demands due to rapid industrialization, environmental concerns with fossil fuel–based generation, diminishing fossil energy resources, transmission network congestion, and technical performance deterioration are the motivations behind the integration of small renewable distributed generation (DG) units and turning the existing power systems into a restructured one. Optimizing the technical benefits offered by DG placement is a well-known challenge for distribution network operators (DNOs) for both fossil and renewable energy resource–based DGs, but renewable DG systems have several power quality (PQ) challenges associated additionally. Power quality is a very significant characteristic of renewable DG systems because today's loads are more sensitive to PQ disturbances and penetration of renewable energy as well as nonlinear loads is proliferating in distribution power networks. So the need for innovative power quality improvement (PQI) techniques becomes inevitable due to ongoing reformation in traditional distribution networks by the integration of renewable energy. This article presents a comprehensive analysis of power quality challenges with grid integration of renewable DG systems and current research status of associated mitigation techniques. Firstly, this paper puts emphasis on theoretically illustrating all the crucial power quality challenges associated with grid integration of renewable energy, and secondly, a thorough survey, of all PQI techniques introduced till date, is elaborated along with highlighting the opportunities for future research. Furthermore, all the crucial power quality issues, the impact of high penetration of renewable energy and mitigation techniques on power quality, are demonstrated also by simulating a grid integrated PV-based DG system in MATLAB/Simulink. This article is believed to be very beneficial for academics as well as industry professionals to understand existing PQ challenges, PQI techniques, and future research directions for renewable energy technologies.     

Modelling of heat transfer and fluid flow in the hot section of gas turbines used in power generation: A comprehensive survey

Power generation is one of the major industries or businesses globally. Although, at present, a major attention has been paid towards the sustainable energy technologies, both gas and steam turbines are still heavily used in the power generation sector worldwide. Usually, gas turbines are used to drive an electrical power generator in simple systems, or they are used in combined cycle plants together with steam turbines. This paper presents a comprehensive review on modelling of heat transfer and fluid flow in hot section of gas turbines used in the power generation sector. Visibly, heat transfer and fluid flow characteristics directly affect the thermal efficiency and the overall performance of the gas turbines. Hence, existing models relating to heat transfer and fluid flow inside gas turbines are discussed in detail. Primarily, methods relating to the first principle modelling, empirical modelling, and finite element modelling are reviewed comprehensively, and then, a discussion is provided together with a comparison among models in terms of their advantages and disadvantages. Moreover, some existing issues such as the environmental impact are discussed which still remain as challenges to the power generation industry together with some of the possible future directions for improvements.     

Status and perspectives of fossil power generation

According to forecasts made by the World Energy Conference and other organizations, fossil fuels such as coal, oil and natural gas will be, in the foreseeable future, our main source for power generation. It is, therefore, very important to use these non-renewable resources with great care and utilize them only in highly efficient plants. This not only conserves our limited reserves but also cuts emissions, thus protecting life, the environment and climatic stability. Technology development will be in particularly high demand during periods of rising fuel prices. To be properly positioned, the electricity markets as well as the available energy conversion technologies and their future development perspectives must be monitored [Power Plant Concepts for Fossil Fuels, VDI-Berichte Nr. 1029, 1993, S. 3; Comparative evaluation of power plants with regard to technical, ecological and economical aspects, in: ASME TURBO EXPO 2001, New Orleans]. An overview is given in the following of state-of-the-art and future power generation technologies, and their development potential, as well as environmental and economic considerations.     

Renewable energy resources and technologies applicable to Ireland

The energy consumed in Ireland is primarily achieved by the combustion of fossil fuels. Ireland's only indigenous fossil fuel is peat; all other fossil fuels are imported. As fossil fuels continually become more expensive, their use as an energy source also has a negative impact on the environment. Ireland's energy consumption can be separated into three divisions: transportation, electricity generation and heat energy. Ireland however has a vast range of high quality renewable energy resources. Ireland has set a target that 33% of its electricity will be generated from renewable sources by 2020 [I. Government. Delivering a Sustainable Energy Future for Ireland; 2007.]. The use of biomass, wind and ocean energy technologies is expected to play a major part in meeting this target. The use of renewable energy technologies will assist sustainable development as well as being a solution to several energy related environmental problems. This paper presents the current state of renewable energy technologies and potential resources available in Ireland. Considering Ireland's present energy state, a future energy mix is proposed.     

Multi-stage stochastic optimization framework for power generation system planning integrating hybrid uncertainty modelling

In this paper, a multi-stage stochastic optimization (MSO) method is proposed for determining the medium to long term power generation mix under uncertain energy demand, fuel prices (coal, natural gas and oil) and, capital cost of renewable energy technologies. The uncertainty of future demand and capital cost reduction is modelled by means of a scenario tree configuration, whereas the uncertainty of fuel prices is approached through Monte Carlo simulation. Global environmental concerns have rendered essential not only the satisfaction of the energy demand at the least cost but also the mitigation of the environmental impact of the power generation system. As such, renewable energy penetration, CO_2,eq mitigation targets, and fuel diversity are imposed through a set of constraints to align the power generation mix in accordance to the sustainability targets. The model is, then, applied to the Indonesian power generation system context and results are derived for three cases: Least Cost option, Policy Compliance option and Green Energy Policy option. The resulting optimum power generation mixes, discounted total cost, carbon emissions and renewable share are discussed for the planning horizon between 2016 and 2030.     

External costs of electricity generation options in Lithuania

This article deals with external cost of electricity generation in Lithuania. The external costs of electricity generation are the most important environmental criteria shaping decisions within the electricity system. External costs of electricity generation were calculated based on ExternE methodology for Lithuania during EU (European Union) Framework 6 project Cost Assessment for Sustainable Energy Systems (CASES). The article presents the methodology and results of external costs of electricity generation in Lithuania. The assessment of external costs provided that future energy policy should be oriented towards the renewable energy generation technologies having the lowest external costs. External costs for electricity generation technologies were analysed in terms of external costs categories, electricity generation technologies life cycle stages and time frame 2010–2030.     

The diffusion of renewable electricity in the presence of climate policy and technology learning: The case of Sweden

The overall objective of this paper is to analyze the impact of climate policy and technology learning on future investments in the Swedish power sector. Methodologically we assess the lifetime engineering costs of different power generation technologies in Sweden, and analyze the impact of carbon pricing on the competitive cost position of these technologies under varying rate-of-return requirements. We also argue that technological learning in the Swedish power sector – not the least in the case of wind power – is strongly related to the presence of international learning and R&D spillovers, and for this reason capacity expansions abroad have important influences of the future cost of power generation in Sweden. The results suggest that renewable power will benefit from existing EU climate policy measures, but overall additional policy instruments (e.g., green certificate schemes) are also needed to stimulate the diffusion of renewable power. Moreover, under a recent European Commission scenario and using estimated learning rates for wind power and the combined cycle gas turbine (CCGT), wind power gains considerable competitive ground due to international technology learning impacts. These latter results are, however, very sensitive to the assumed learning-by-doing rates for wind power and CCGT, respectively.     

Flywheel array energy storage system

飞轮储能系统将能量储存在高速旋转的飞轮转子中,具有高功率密度,无环境污染,使用寿命长,运行温度范围广,充放电次数无限制等优点,已获得了广泛的应用.将多台模块化的飞轮储能单元并联起来组成飞轮阵列储能系统,是获得大容量,高功率储能的解决方案.文章首先论述了飞轮阵列储能系统的国内外发展现状与要解决的关键问题, 然后详细给出了飞轮阵列储能系统的设计方法,并联拓扑结构与控制策略.随着飞轮储能单元并联技术的逐渐成熟,飞轮阵列储能系统应用领域将逐步扩展到电力系统调频,间歇式可再生能源发电等领域,并将在提高电网对可再生能源的接纳能力等方面发挥重要作用.     

Assessment of biofuels supporting policies using the BioTrans model

The introduction of advanced, 2nd generation biofuels is a difficult to forecast process. Policies may impact the timing of their introduction and the future biofuels mix. The least-cost optimization model BioTrans supports policy analyses on these issues. It includes costs for all parts of the supply chain, and endogenous learning for all biofuels technologies, including cost reductions through scale. BioTrans shows that there are significant lock-in effects favouring traditional biofuels, and that the optimal biofuels mix by 2030 is path dependent. The model captures important barriers for the introduction of emerging technologies, thereby providing valuable quantitative information that can be used in analyses of biofuels supporting policies. It is shown that biodiesel from oil crops will remain a cost effective way of producing biofuels in the medium term at moderate target levels. Aiming solely at least-cost biofuel production is in conflict with a longer term portfolio approach on biofuels, and the desire to come to biofuels with the lowest greenhouse gas emissions. Lowering the targets because of environmental constraints delays the development of 2nd generation biofuels, unless additional policy measures (such as specific sub targets for these fuels) are implemented.     

Life cycle energy,emissions and cost inventory of power generation technologies in Singapore

Singapore is one of the most industrialised and urbanised economies in South-East Asia. Power supply is an important sub-system in its economy and heavily reliant on imported oil and natural gas. Due to its geographical area, clean/renewable energy sources for power generation are limited. At the same time, in its deregulated electricity market, the adoption of clean/renewable based power generation technology may be hindered by a market pricing mechanism that does not reflect externality costs. For a sustainable power supply, there is a need to change the conventional appraisal techniques. Life cycle assessment (LCA) and life cycle cost analysis (LCCA) are good tools to quantify environmental impacts and economic implications. LCA and LCCA are performed for centralised and distributed power generation technologies in Singapore, namely, oil and Orimulsion-fired steam turbines, natural gas-fired combined cycle plant, solar PV and fuel cell systems. A life cycle energy, emission and cost inventory is established. The results are discussed from the perspectives of fuel security, environmental protection and cost effectiveness of future power generation strategies for Singapore.     

Progress and prospects of innovative coal-fired power plants within the energy internet

The development of electrical engineering and electronic, communications, smart power grid, and ultra-high voltage transmission technologies have driven the energy system revolution to the next generation: the energy internet. Progressive penetration of intermittent renewable energy sources into the energy system has led to unprecedented challenges to the currently wide use of coal-fired power generation technologies. Here, the applications and prospects of advanced coal-fired power generation technologies are analyzed. These technologies can be summarized into three categories: (1) large-scale and higher parameters coal-fired power generation technologies, including 620/650/700 °C ultra-supercritical thermal power and double reheat ultra-supercritical coal-fired power generation technologies; (2) system innovation and specific, high- efficiency thermal cycles, which consist of renewable energy-aided coal-fired power generation technologies, a supercritical CO₂ Brayton cycle for coal-fired power plants, large-scale air-cooling coal-fired power plant technologies, and innovative layouts for waste heat utilization and enhanced energy cascade utilization; (3) coal-fired power generation combined with poly-generation technologies, which are represented by integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) technologies. Concerning the existing coal-fired power units, which are responsible for peak shaving, possible strategies for enhancing flexibility and operational stability are discussed. Furthermore, future trends for coal-fired power plants coupled with cyber-physical system (CPS) technologies are introduced. The development of advanced, coal-fired power generation technologies demonstrates the progress of science and is suitable for the sustainable development of human society.     

Impacts of environmental product legislation on solid oxide fuel cells

Ongoing development of solid oxide fuel cell (SOFC) technology coincides with a rapid increase in legislation aiming to control the environmental impacts of products across their life cycle. A risk-based method is used to explore the potential future impacts of this body of legislation on the technology. Legislation controlling the use of hazardous materials is one area of significance. Under the new European REACH Regulation some nickel compounds, used widely throughout general industry but also in the fabrication of anode structures, may fall under the classification of a substance of very high concern (SVHC) in future, which presents a risk of restrictions being placed on their continued use. This risk must drive the development of alternative anode materials, or requires the SOFC industry to identify a socio-economic argument justifying exemption from any future restrictions. A legislative trend establishing recycling requirements for end-of-life products is also identified as having a potential future impact on the technology. Recycling strategies for SOFC products must be considered, prior to commercialisation. It is proposed that failure to meet these future environmental requirements may be detrimental to the perception of SOFC technology, the demand for which is substantially driven by the environmental benefits offered over incumbent power generation technologies. The consideration of these issues in the design of commercial products will mitigate this risk.     

Hydrogen as fuel: a critical technology?

The potential of hydrogen energy technologies for being recognized as critical technologies (CTs) in the context of sustainable development is briefly discussed in view of the assessment approach and definitions accepted pertaining to CTs by the institutions dedicated to science and technology policy development.The concepts of sustainable development, the relationship between the level of national income and the extent of energy utilisation, CTs in general and national CTs (NCTs) are considered for different types of countries at different stages of economic development.Views of industry and business sectors on CTs and the roles of governments and universities are emphasized. The influence of public acceptance of hydrogen as a fuel is included.It is concluded that in addition to its exceptionally constructive environmental impact at the local, regional and global levels: hydrogen is expected to bring about a substantial change in the present state of affairs by creating a large number of new and diverse technologies, vast employment opportunities in all sectors and by delivering highly efficient and decentralized energy utilisation, free of geopolitical dependence in most cases. In this regard, though hydrogen is considered as a possibility presently, in the near future hydrogen energy technologies will inevitably be recognised as CTs for countries that are consciously adjusting for sustainable development.     

生物质能发电技术分析

在不可再生能源濒临枯竭,环境污染日益加剧的今天,生物质能源替代化石能源利用的研究和开发,已成为国内外学者研究和关注的热点。介绍了国内外生物质能的主要转化利用技术,分析了生物质直接燃烧发电技术和气化发电技术,提出了符合能量梯级利用原则的生物质能发电方式,将是生物质能利用的主要形式。