Preliminnary Study On Fast And Efficient Solar Heat Storage With Biogas

As a clean, environmentally friendly green energy, the large-scale development and utilization of renewable energy has become an important way to solve the 21st century to solve the energy shortage, environmental pollution, the greenhouse effect and other issues caused by fossil fuels. Among them, The promotion and application of the solar collection and biogas technology attract much attention. However, the large-scale use of solar thermal energy is still subject to some limitations:the solar radiation energy density Earth receiving is low, the intermittent solar radiation and its fluctuation with day and night, seasons and climate, it's difficult to store solar energy. Meanwhile, the traditional biogas technology also subject to day and night, seasons, climates and other factors. The phenomenon of low gas production rate, less gas production and no gas production in winter of the conventional digesters is widespread.To compensate for the lack of the solar collection and biogas technology, we combine these two techniques with each other's advantages. A new method of fast and efficient solar heat storage with biogas was put forward. An experimental study on the device was carried out in Lanzhou. Analysised its thermal performance, economic and environmental benefits, we obtained the following results:1. The device of effective volume 4 m3 can produce biogas 2.4 m3 per day in winter. Its volume gas production rate archived 0.6m3/(m3·d). The fermentation time was about 30 days. The gas production rate will increase substantial in the warm season. The device can supply energy stably and efficiently throughout the year;2. The collaboration of heating, heat transfer and temperature control part is good. The device can archive constant temperature fermentation;3. In winter, the solar heat storage efficiency was up to 0.65. It transformed the low-grade (energy grade,0.074) unstable solar energy and biomass energy (energy grade,0.419) to the high-grade stable biogas chemical energy (energy grade, 0.830)and achieved significantly improve on the energy grade;4. Using the method of dynamic economic to appraise the entire system. The project's financial net present value NPV (i=10%) was￥6794.35, internal rate of return IRR was 26.46%, the internal returns ratio was 1.50, the dynamic investment recovery period was 5.2 years;5. Device has a good ecological benefit and social benefit. Protection of forest area per year can be 0.44 ha..Coal burning replaced as the standard, the annual emissions of carbon dioxide and sulfur dioxide can be 1.30t and 0.026t per year; Compared with the conventional digester, the annual emissions of carbon dioxide and sulfur dioxide can be 1.03t and 0.021t per year. It also can play an important role in improving living quality of farmers, labor-saving, promoting science, optimizing the industrial structure and other aspects.The innovation of this topic is:A new method of fast and efficient solar heat storage with biogas was put forward. The energy conversion efficiency and upgrade principle of energy grade was initial quantitative theoretical revealed in the process of transforming.The findings have important academic values and good social and economic benefits. It presents a new low-temperature solar thermal energy storage mode, the solar collector-gas chemical energy storage, which achieved the efficient conversation of low-grade unstable solar heat and low-grade biomass energy to the high-grade stable high-energy-density biogas energy. It breaks out the limits of the day and night, seasons, weather and other factors theoretically and technically, expands the applications of traditional solar collector system and anaerobic fermentation technology, achieves high efficiency and low cost development of solar heat and biomass energy. In the strong support from national policy, these finding can be used broadly in biogas power generation, municipal solid waste resource use, wastewater treatment, large-scale anaerobic treatment of livestock manure and organic wastewater anaerobic treatment in wine sugar industry and other industrial areas. Moreover, the results of these studies have positive effects on meeting rural energy needs using rural energy, promoting the building of socialist new countryside, China's energy structure adjustment, the development of renewable energy and alternative fuel technologies. It can save energy significantly,reduce environmental releases, and have good social benefits.