Direct conversion of the tremendous and ubiquitous low-grade thermal energy into electricity by thermogalvanic cells is a promising strategy for energy harvesting. The environment is one of the richest and renewable low-grade thermal source. However, critical challenges remain for all-day electricity generation from environmental thermal energy due to the low frequency and small amplitude of temperature fluctuations in the environment. In this work, we report a tandem device consisting of a polypyrrole (PPy) broadband absorber/radiator, thermogalvanic cell, and thermal storage material (Cu foam/PEG1000) that integrates multiple functions of heating, cooling, and recycling of thermal energy. The thermogalvanic cell enables continuous utilization of environmental thermal energy at both daytime and nighttime, yielding maximum outputs as high as 0.6 W m-2 and 53 mW m-2, respectively. As demonstrated outdoors by a large-scale prototype module, this design offers a feasible and promising approach to all-day electricity generation from environmental thermal energy.
At present, China is the world's largest energy consuming country and industrial manufacturing country, especially industrial enterprises are the main energy consumers. The steel industry occupies an important position in China's national economy, and has the characteristics of high energy consumption, high pollution and high emissions. Therefore, based on the perspective of energy management, this paper selects 54 large-scale steel companies from China Iron and Steel Association from 2009 to 2017 as a sample, and applies the SBM super-efficiency model that includes undesired output and the differences-in-differences (DID) method to explore the impact of companies implementing energy management systems on corporate performance. The empirical results show that: the implementation of energy management system has a positive impact on enterprise performance. Moreover, the impact of energy management system on economic performance is greater than that on environmental performance. Through the analysis of regional heterogeneity and ownership heterogeneity, it is further found that the implementation of energy management system in eastern region enterprises and stateowned enterprises has a more obvious impact on enterprise performance. The results of this paper can encourage those managers who want to apply energy management system in enterprises to achieve sustainable development, so as to improve the efficiency and results of energy management.
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