Comparing electricity,heat and biogas storages’ impacts on renewable energy integration

Increasing penetration of fluctuating energy sources for electricity generation, heating, cooling and transportation increase the need for flexibility of the energy system to accommodate the fluctuations of these energy sources. Controlling production, controlling demand and utilising storage options are the three general categories of measures that may be applied for ensuring balance between production and demand, however with fluctuating energy sources, options are limited, and flexible demand has also demonstrated limited perspective. This article takes its point of departure in an all-inclusive 100% renewable energy scenario developed for the Danish city Aalborg based on wind power, bio-resources and low-temperature geothermal heat. The article investigates the system impact of different types of energy storage systems including district heating storage, biogas storage and electricity storage. The system is modelled in the energy systems analyses model energyPRO with a view to investigating how the different storages marginally affect the amount of wind power that may be integrated applying the different storage options and the associated economic costs. Results show the largest system impact but also most costly potential are in the form of electricity storages.     

Sustainable electricity generation fuel mix analysis using an integration of multicriteria decision-making and system dynamic approach

To achieve a national energy access target of 90% urban and 51% rural by 2035, combat climate change, and diversify the energy sector in the country, the Zambian government is planning to integrate other renewable energy resources (RESs) such as wind, solar, biomass, and geothermal into the existing hydro generation–based power system. However, to achieve such targets, it is essential for the government to identify suitable combination of the RESs (electricity generation fuel mix) that can provide the greatest sustainability benefit to the country. In this paper, a multicriteria decision-making framework based on analytic hierarchy process and system dynamics techniques is proposed to evaluate and identify the best electricity generation fuel mix for Zambia. The renewable energy generation technologies considered include wind, solar photovoltaic, biomass, and hydropower. The criteria used are categorized as technical, economic, environmental, social, and political. The proposed approach was applied to rank the electricity generation fuel mix based on nine sustainability aspects: land use, CO₂ emissions, job creation, policy promotion affordability, subsidy cost, air pollution reduction, RES electricity production, RES cumulative capacity, and RES initial capital cost. The results indicate that based on availability of RESs and sustainability aspects, in overall, the best future electricity generation mix option for Zambia is scenario with higher hydropower (40%) penetration, wind (30%), solar (20%), and lower biomass (10%) penetration in the overall electricity generation fuel mix, which is mainly due to environmental issues and availability of primary energy resources. The results further indicate that solar ranks first in most of the scenarios even after the penetration weights of RES are adjusted in the sensitivity analysis. The wind was ranked second in most of the scenarios followed by hydropower and last was biomass. These developed electricity generation fuel mix pathways would enable the country meeting the future electricity generation needs target at minimized environmental and social impacts by 2035. Therefore, this study is essential to assist in policy and decision making including planning at strategic level for sustainable energy diversification.     

Turkey's Renewable Energy Facilities in the Near Future

In this work, renewable energy facilities of Turkey were investigated. Electricity is mainly produced by thermal power plants, consuming coal, lignite, natural gas, fuel oil and geothermal energy, and hydro power plants in Turkey. Turkey has no large oil and gas reserves. The main indigenous energy resources are lignite, hydro and biomass. Turkey has to adopt new, long-term energy strategies to reduce the share of fossil fuels in primary energy consumption. For these reasons, the development and use of renewable energy sources and technologies are increasingly becoming vital for sustainable economic development of Turkey. The most significant developments in renewable production are observed hydropower and geothermal energy production. Renewable electricity facilities mainly include electricity from biomass, hydropower, geothermal, and wind and solar energy sources. Biomass cogeneration is a promising method for production bioelectricity.     

Potential of geothermal energy in the Kingdom of Saudi Arabia

The Kingdom of Saudi Arabia has rich geothermal energy resources. In Saudi Arabia, the studies on geothermal resources exploration were started in 1980. Saudi Arabia is among the most geothermally active countries in the Middle East. The geothermal power plants are not yet installed in Saudi Arabia. Some direct-use low-grade geothermal applications are already installed in the five last years. Some refreshment and swimming pools are already constructed in the Bani Malik-Jizan area. Geothermal energy can be utilized in various forms such as direct use, electricity generation, space heating, heat pumps, greenhouse heating, and industrial usage. The Kingdom of Saudi Arabia government has plans to become completely powered by difference forms of renewable energy such as solid waste, solar, geothermal, and wind.     

Global Renewable Energy Resources

Renewable energy sources (RES) supply 14% of the total world energy demand. RES are biomass, hydropower, geothermal, solar, wind, and marine energies. The renewables are the primary, domestic and clean or inexhaustible energy resources. The percentage share of biomass was 62.1% of total renewable energy sources in 1995. Large-scale hydropower supplies 20 percent of global electricity. Wind power in coastal and other windy regions is promising as well.     

Current utilization and future prospects of emerging renewable energy applications in Canada

Canada has vast renewable energy resources due to its extensive geography and traditionally they have played an important role, particularly prior to the turn of the 20th century. Public interest in new renewable energy technologies (RETs) emerged and grew during the oil shocks of the 1970s and early 1980s. Even though many Canadian provinces had been deriving most of their electricity from hydroelectric power, the first oil crises of the 1970s ignited a strong interest in all forms of renewable energy. Though Canada has huge prospects for low-impact RETs, it is falling behind most industrialized nations in the expansion of these technologies due to a lack of supporting market structures and the absence of appropriate government policies and initiatives. This review focuses on only applications of low-impact emerging RETs that refer to wind, solar, small hydro, geothermal, marine and modern biomass energy. Today, these technologies are mostly in the dissemination, demonstration and early stage of commercialization phase in Canada and currently they contribute less than 1% of the total primary energy consumption. It is evident from the past experience of Europe and Japan that environmentally benign RETs can contribute significantly toward Canada’s Kyoto target of reducing greenhouse gas emissions by displacing the use of conventional fossil fuels, and help Canada take an essential step toward a sustainable energy future. In this paper, the current energy utilization scenario of Canada has been analyzed and an array of emerging RET applications has been presented under the category of: (i) green power technologies; (ii) green heat technologies; and (iii) green fuel technologies.     

The role of renewable and sustainable energy in the energy mix of Malaysia: a review

Energy consumption has risen in Malaysia because of developing strategies and increasing rate of population. Depletion of fossil fuel resources, fluctuation in the crude oil prices, and emersion of new environmental problems due to greenhouse gasses effects of fossil fuel combustion have convinced governments to invest in development of power generation based on renewable and sustainable energy (RSE) resources. Recently, power generation from RSE resources has been taken into account in the energy mix of every country to supply the annual electricity demand. In this paper, the scenario of the energy mix of Malaysia and the role of RSE resources in power generation are studied. Major RSE sources, namely biomass and biogas, hydro‐electricity, solar energy, and wind energy, are discussed, focusing more toward the electrical energy demand for electrification. It is found that power generation based on biomass and biogas utilization, solar power generation, and hydropower has enough spaces for more development in Malaysia. Moreover, minihydropower and wind power generation could be effective for rural regions of Malaysia. Copyright © 2014 John Wiley & Sons, Ltd.     

Intermittent renewable energy: The only future source of hydrogen?

In this paper we assess the feasibility of various future energy production pathways for hydrogen. We argue that neither nuclear energy, nor coal gasification with carbon collection and storage can provide sufficient climate-neutral energy to be probable routes to a hydrogen future. Their contributions are likely to be too little and too late to be of much help. Hydroelectricity, geothermal and biomass energy can all provide base-load power, but even combined have limited potential, and are not always climate-neutral in operation. On the other hand, the high-potential renewable energy (RE) sources, particularly wind and direct solar energy, are intermittent. Further, wind resources are poorly matched to the existing distribution of world population. Wind power's high potential compared with present electricity demand, high return on energy invested, intermittency, and mismatch with load centres all favour hydrogen conversion and transmission to load centres.     

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.     

A renewable energy system in Frederikshavn using low-temperature geothermal energy for district heating

The Danish city Frederikshavn is aiming at becoming a 100% renewable energy city. The city has a number of energy resources including a potential for off-shore wind power, waste and low-temperature geothermal energy usable as heat source for heat pumps producing district heating.     

Heat planning for fossil-fuel-free district heating areas with extensive end-use heat savings: A case study of the Copenhagen district heating area in Denmark

The Danish government plans to make the Danish energy system to be completely free of fossil fuels by 2050 and that by 2035 the energy supply for buildings and electricity should be entirely based on renewable energy sources. To become independent from fossil fuels, it is necessary to reduce the energy consumption of the existing building stock, increase energy efficiency, and convert the present heat supply from fossil fuels to renewable energy sources. District heating is a sustainable way of providing space heating and domestic hot water to buildings in densely populated areas. This paper is a theoretical investigation of the district heating system in the Copenhagen area, in which heat conservation is related to the heat supply in buildings from an economic perspective. Supplying the existing building stock from low-temperature energy resources, e.g. geothermal heat, might lead to oversized heating plants that are too expensive to build in comparison with the potential energy savings in buildings. Long-term strategies for the existing building stock must ensure that costs are minimized and that investments in energy savings and new heating capacity are optimized and carried out at the right time.     

地热资源的开发利用及可持续发展

地热资源作为一种新型能源矿产,具有分布广泛、易于开发等特点,其利用方式主要有地热发电和地热直接利用两种.我国具有良好的地热资源条件,主要为中低温地热资源.据计算,我国12个主要沉积盆地的地热可开采资源量为7500×1018J,相当于2560×108t标煤.当前,我国地热资源利用方式主要以供暖、洗浴、种植等直接利用为主;地热发电发展缓慢,主要分布在西藏;利用热泵技术开发地热资源得到了快速发展;油区地热资源的开发利用也取得了良好的经济和社会效益.但同时我国地热资源产业也面临着一些问题,包括大部分地区尚未开展地热资源勘查评价,影响了地热资源规划的制订及地热产业的发展;防腐、防垢技术还需要进一步加强研究;地热回灌率普遍过低;增强型地热系统研究有待加强等.为了促进地热资源的可持续发展,建议在加大地热资源勘查力度的同时,应以浅层地温能和热水型地热资源为主,发挥热泵技术的优势,开展地热资源的综合利用及梯级利用;重视和加快油气区地热资源的利用;在西藏等适宜地区加大高温地热能发电利用;集中全国优势技术力量,在一两个有利区域开展增强型地热系统技术探索;此外,走回灌开发道路是地热资源开发利用的必然选择.     

Means to reduce CO2-emissions in the Chinese electricity system, with special consideration to wind energy

This paper analyses the technical possibilities which exist to avoid a large increase of carbon dioxide emissions produced by electricity generation in China.The paper evaluates different technical means such as wind energy, solar energy (thermal and Pl), hydro energy, tidal energy, geothermal energy and biomass for electricity production in China. The potential of each power source is estimated. In a final scenario, the influence of these technical means on the CO₂ reduction in the year 2020 will be predicted.     

高寒地区百分百可再生能源住宅的可行性分析

充分利用高寒地区自然资源的优势，将地源热泵技术与被动式太阳房技术，太阳能光电转换技术，几力发电等技术综合利用，对利用百分之百可再生能源满足民用会计室采暖，日常生活用能的可能性进行理论分析和论证，结果表明，高寒地区住宅用能源实现百分百可再生能源是完全可能的。     

Status and outlook of China's free-carbon electricity

Global warming, increased energy demand, and tremendous air pollution are forcing China to revise its energy structure of electricity generation dominated by coal (80% of total electricity) towards low-carbon electricity. Vigorous development of carbon-free energy resources of electricity is a practical way towards low-carbon electricity in China. In this paper, we shall outline renewable power generation (hydropower, wind power, solar energy, biomass energy, nuclear power, ocean energy and geothermal) together with nuclear power for China, present a reserves assessment, the current status, and barriers for further development, and finish with an outlook towards the future. In our view, China has plenty of free-carbon energy resources to revolutionize its electricity structure and redirect it towards low-carbon electricity systems. Needed are the effective energy policies to get to the way.     

Life cycle assessment of geothermal binary power plants using enhanced low-temperature reservoirs

Geothermal binary power plants that use low-temperature heat sources have gained increasing interest in the recent years due to political efforts to reduce greenhouse gas emissions and the consumption of finite energy resources. The construction of such plants requires large amounts of energy and material. Hence, the question arises if geothermal binary power plants are also environmentally promising from a cradle-to-grave point of view. In this context, a comprehensive Life Cycle Analysis (LCA) on geothermal power production from EGS (enhanced geothermal systems) low-temperature reservoirs is performed. The results of the analysis show that the environmental impacts are very much influenced by the geological conditions that can be obtained at a specific site. At sites with (above-) average geological conditions, geothermal binary power generation can significantly contribute to more sustainable power supply. At sites with less favorable conditions, only certain plant designs can make up for the energy and material input to lock up the geothermal reservoir by the provided energy. The main aspects of environmentally sound plants are enhancement of the reservoir productivity, reliable design of the deep wells and an efficient utilization of the geothermal fluid for net power and district heat production.     

低温热能发电的研究现状和发展趋势

低温热能种类繁多,数量巨大,利用这部分能源意义重大。介绍了低温热能发电技术的研究现状和发展趋势。低温热能发电技术主要应用于太阳能热电、工业余热发电、地热发电、生物质能发电、海洋温差发电等方面。现阶段低温热能发电的研究重点有:工质的热物性和环保性能、循环优化研究;提高低温热能发电效率的研究,包括混合工质循环、Kalina循环、回热、氨吸收式动力制冷循环等;基于有限时间热力学的系统最优控制等方面的研究。     

Geothermal‐based hydrogen production using thermochemical and hybrid cycles: A review and analysis

Geothermal‐based hydrogen production, which basically uses geothermal energy for hydrogen production, appears to be an environmentally conscious and sustainable option for the countries with abundant geothermal energy resources. In this study, four potential methods are identified and proposed for geothermal‐based hydrogen production, namely: (i) direct production of hydrogen from the geothermal steam, (ii) through conventional water electrolysis using the electricity generated through geothermal power plant, (iii) by using both geothermal heat and electricity for high temperature steam electrolysis and/or hybrid processes, and (iv) by using the heat available from geothermal resource in thermochemical processes. Nowadays, most researches are focused on high‐temperature electrolysis and thermochemical processes. Here we essentially discuss some potential low‐temperature thermochemical and hybrid cycles for geothermal‐based hydrogen production, due to their wider practicality, and examine them as a sustainable option for hydrogen production using geothermal heat. We also assess their thermodynamic performance through energy and exergy efficiencies. The results show that these cycles have good potential and attractive overall system efficiencies over 50% based on a complete reaction approach. The copper‐chlorine cycle is identified as a highly promising cycle for geothermal‐hydrogen production. Copyright © 2009 John Wiley & Sons, Ltd.     

A methodology for analysis of impacts of grid integration of renewable energy

Present electricity grids are predominantly thermal (coal, gas) and hydro based. Conventional power planning involves hydro-thermal scheduling and merit order dispatch. In the future, modern renewables (hydro, solar and biomass) are likely to have a significant share in the power sector. This paper presents a method to analyse the impacts of renewables in the electricity grid. A load duration curve based approach has been developed. Renewable energy sources have been treated as negative loads to obtain a modified load duration curve from which capacity savings in terms of base and peak load generation can be computed. The methodology is illustrated for solar, wind and biomass power for Tamil Nadu (a state in India). The trade-offs and interaction between renewable sources are analysed. The impacts on capacity savings by varying the wind regime have also been shown. Scenarios for 2021–22 have been constructed to illustrate the methodology proposed. This technique can be useful for power planners for an analysis of renewables in future electricity grids.