Techno-Economic Analysis of Parabolic Trough Collectors : A case study for two industrial parks in Zhejiang, China

Abstract: Transitioning the industrial sector’s energy system to renewable sources is crucial to reduce climate change. There is no exception for China, currently having the highest absolute levels of greenhouse gas (GHG) emissions in the world. The industrial sector accounts for about two thirds of the national energy consumption and coal is the country’s most important energy source. The integration of alternative energy sources such as solar can help transitioning the country’s energy system. By presenting a techno-economic analysis, this thesis gives an indication for profitability and in what extent there is a potential to cover the steam demand with a decentralized solar heat technology for two industries, fish and textile, in the Zhejiang province in eastern China. The used solar technology is a system with parabolic trough collectors (PTCs) with an integrated gas fired boiler. The PTC-system is compared with a coal-fired centralized supplier. The analyzed factors were roof area, solar irradiation, solar fraction, cost for steam from the centralized suppliers and cost of coal and natural gas. The maximum CO2 reduction is found to be dependent on the potential installation area. The greater area installed, the larger is the capacity and thus also the CO2 savings. The share of total steam demand covered by solar is directly proportional to the demand in relation to the installed solar capacity. The fish industry, having the lowest steam demand in relation to the roof area, is found to be able to save the largest relative proportion of CO2 emissions. Different scenarios are presented, modifying the fuel cost and fuel type for the PTC-system’s boiler, adjusting the steam cost from the centralized suppliers and using two different solar fractions of 35% and 50%. The CO2 savings depends on what fuel is being used and the solar fraction. Larger CO2 reductions are possible with a gas fired boiler compared to a coal fired one. But using a coal fired boiler makes it more economically profitable, matching the low coal price used for the centralized supplier. The scenario with most CO2 reductions is attained when using a high solar fraction of 50% and a natural gas fired boiler. The annual CO2 savings is then ranging from 15 tons per year for the company having the lowest steam capacity, up to 2090 tons/year for the company with one of the highest. Another significant factor is the companies’ seasonal activity. For the company having the least amount of active days per year (84 out of 365 days), the PTC-system is unprofitable whichever scenario. However, fuel costs for the boiler is found to be one of the most significant factors for the outcome determining if the investigated PTC-system is profitable or not. For all of the companies, there was only one that could provide all its steam demand with the PTC-system. This indicates that other energy sources need to be integrated to provide the steam demand of the enterprises with a renewable energy system.