Annual performance of solar tower aided coal-ﬁred power generation system Yong Zhu a, b , Rongrong Zhai a, * , Jiawei Qi a , Yongping Yang a , M.A. Reyes-Belmonte b , Manuel Romero b , Qin Yan c a School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China b IMDEA Energy Institute, Ramon de la Sagra 3, 28935 M ostoles, Spain c China Datang Corporation Renewable Power Co., Limited, Beijing 100053, China article info Article history: Received 27 June 2016 Received in revised form 14 October 2016 Accepted 6 November 2016 Available online xxx Keywords: Annual thermodynamic characteristics Solar tower aided power generation Solar multiple Thermal energy storage Solar contribution abstract Solar tower aided coal-ﬁred power generation system (STCG) is able to provide high solar utilization efﬁciency with low coal consumption rate. This paper compares performances of a solar tower aided coal-ﬁred power plant, a solar tower power plant and a coal-ﬁred power plant under different operative conditions. The comparison includes various solar multiple and thermal energy storage size. According to solar radiation resource and grid power dispatching demand, STCG, solar tower power generation system (STG) and coal-ﬁred power generation system (CPG) work under off-design conditions all the year around. Results show that STCG has higher solar utilization efﬁciency than STG and lower coal con- sumption rate and CO 2 emission rate than CPG. In addition, solar-to-electricity exergy efﬁciency of STCG is at least 1.83% higher than that of STG. Compared to CPG, the 1000 MWe STCG can reduce coal con- sumption by 2.0  10 5 t/y, with the saving ratio being 10.4%. The annual average coal consumption rate of STCG is 27.3 g/kWh lower than that of CPG. In addition, the annual average CO 2 emission rate of STCG is reduced by 10.1% compared with that of CPG. Solar tower aided coal-ﬁred power generation can facilitate energy conservation and emission reduction of STG and CPG. © 2016 Published by Elsevier Ltd. 1. Introduction Coal-ﬁred power plants are the most usual way of power gen- eration in China's electricity market. By the end of 2013, electricity generated by coal accounted for 74% of the total [1]. In recent years, over-exploitation of fossil fuels has led to serious environmental pollution and global warming issues [2]. Therefore, it is important to optimize power sector structure, accelerate innovation in energy technology, increase the proportion of renewable energy in power generation, and enhance the utilization efﬁciency of fossil fuels [3]. In addition, it is also one of the requirements of China's “13th Five Year Plan” [4]. Compared with wind power and photovoltaics, solar thermal combined with thermal storage can generate electricity steadily under variable solar radiation conditions. As a result, solar thermal power generation is the most promising technology for non-fossil energy utilization [5e7]. It is in accordance with the requirements of Chinese National Energy Administration “To vigorously develop solar energy, continue to promote the con- struction of solar thermal power generation demonstration pro- jects, and explore new technologies and models of solar thermal power generation” [8]. In China, solar thermal power generation is still in an early stage of development, and the high initial invest- ment of solar thermal power plants is a major barrier to the deployment of this technology [9]. The integration of solar thermal energy with coal-ﬁred power plant can lead to higher utilization efﬁciency of solar thermal energy and lower CO 2 emission because of the high parameters (high temperature and pressures) and large capacity of CPG. In addition, by sharing the power block system with the coal-ﬁred power plant [10], the initial investment of a solar thermal power plant can also be reduced. Large-scale coal- ﬁred power plants featuring large capacity and high-performance working operative conditions (temperature and pressure) can run under variable loads. These characteristics can be used to alleviate the impacts on power generation system by variable solar radiation and further mitigate the negative effect on grid, which is in line with the current electricity market in China. Many researchers have conducted deep studies on solar aided * Corresponding author. E-mail address: zhairongrong@gmail.com (R. Zhai). Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy http://dx.doi.org/10.1016/j.energy.2016.11.023 0360-5442/© 2016 Published by Elsevier Ltd. Energy xxx (2016) 1e13 Please cite this article in press as: Zhu Y, et al., Annual performance of solar tower aided coal-ﬁred power generation system, Energy (2016), http://dx.doi.org/10.1016/j.energy.2016.11.023