Low-Cost Distributed Solar-Thermal-Electric Power Generation

低成本分布式太阳能热电发电我们讨论了一种基于太阳能集热器(STC)和自由活塞式斯特林发动机相结合的低成本分布式太阳能热电发电技术的技术和经济可行性。太阳能集热器将由低浓度的非成像聚光器和带有光谱选择性涂层的吸收器组成。斯特林引擎通过集成发电的方式将中温热转化为电能。由于其转换效率相对较低，所提出的系统可以是一种成本低廉的太阳能光伏(PV)组件，如项目描述中所讨论的。系统被设想在集热温度在125摄氏度至150摄氏度的范围内运行，这与使用低浓度非成像接收器的固定式太阳能集热器的使用是一致的。因此，该系统避免了基于高聚光比聚光器的跟踪集热器的成本和维护问题。我们认为，太阳能电力技术的成本效率应该以单位美元的输出功率来衡量，而不是以效率或其他技术价值来衡量。这种观点反映了这样的观察：世界上无论是城市还是农村地区都有巨大的未开发的定位机会。对光伏的研究一直集中在提高效率上，因为硅片的固有成本并没有显著降低。然而，所提出的太阳能-热电系统是用低成本材料制造的。集热器是用玻璃、铝、铜和绝缘材料建造的而发动机和发电机主要是钢、铝、铜和塑料。在大批量制造中，建议的系统的成本将由其散装材料的重量决定。这项关于太阳能-热电系统的研究涉及在系统成本和材料成本之间寻找更具成本效益的平衡。通过使用可再生分布的能源来影响能源独立和分流对我们的社会的未来是至关重要的。在项目描述中，我们假设建议的技术将花费大约1美元每瓦的峰值输出功率。因此，这项技术将至少比光伏技术的成本提高五倍。使用所提出的技术，基于在不大的十年寿命内平均每天只运行四个小时，对能源成本的简单估计表明，成本约为0.066美元/千瓦时。尽管不等于最低的电力成本，但考虑到其本身的额外优势，这无疑是一种使该技术非常有价值的能源成本。同样，这是一种分布式可再生能源，其可用性与高峰需求时间相当匹配。此外，该技术非常适合以类似于光伏发电的方式进行分布式部署对于那些不存在或过于昂贵的公用事业基础设施的偏远地区，以及作为光伏发电替代方案的住宅和商业地点，这将是有价值的。PI一直积极将研究整合到新的和现有的班级中，并计划将这一点与拟议的工作结合起来。PI还积极寻求将贫困的学生群体纳入他的项目。加州大学伯克利分校主办了加州大学伯克利分校工程研究暑期本科生计划，Http://www.coe.berkeley.edu/cues/superb/index.html)program是面向未被充分代表的少数族裔学生的。PI计划在暑期积极招募学生参加拟议的项目。智力价值通过寻求最小化成本/输出功率比来实现使可再生能源成为可能的直接战略。我们分析了包括太阳能集热器和低温斯特林发动机的集成系统的成本。提出了新颖的多相自由活塞式斯特林机械设计，并对其设计和评估进行了严格的分析。讨论了一种没有机械连接，只有三个运动部件的斯特林机器。这是一种本质上允许长时间免维护和极低摩擦损失的设计。

Low-Cost Distributed Solar-Thermal-Electric Power GenerationWe discuss the technical and economic feasibility of a low-cost distributed solar-thermal-electricpower generation technology based on the use of a solar thermal collector (STC)in conjunction witha free-piston Stirling engine.The solar thermal collector is to be comprised of low-concentrationnonimaging concentrators and absorbers with spectrally selective coatings.The Stirling engineconverts moderate temperature heat to electricity by way of integrated electric generation.In spiteof its relatively low conversion e .ciency,the proposed system can be a cost-e .ective alternative tosolar photovoltaic (PV)modules,as discussed in the project description.The system is conceived to operate with collector temperatures in the range of 125 .C to 150 .C,which is consistent with the use of stationary solar thermal collectors employing low-concentrationnonimaging re .ectors.Thus,the system avoids the costs and maintenance issues associated withtracking collectors based on high concentration ratio concentrators.We take the view that cost e .ectiveness of solar electric technologies should be judged byoutput power per dollar rather than by e .ciency or other technical merits.This view re .ects theobservation that there are vast untapped siting opportunities in both urban and rural regions ofthe world.Research into photovoltaics has been focused on improving e .ciency because therehas been no signi .cant decrease in the inherent cost of silicon wafer area.However,the proposedsolar-thermal-electric system is designed for fabrication out of low-cost materials.A collector isbuilt of glass,aluminum,copper,and insulation,while engines and generators are primarily steel,aluminum,copper,and plastics.In high-volume manufacturing,the cost of the proposed systemwill be determined by the weight of its bulk materials.This study of solar-thermal-electric systemsinvolves searching for a more cost-e .ective balance between system e .ciency and materials cost.Broader Impacts Energy independence and diversi .cation through the use of renewable dis-tributed sources is essential for the future of our society.In the project description,we make a casethat the proposed technology will cost on the order of $1 per Watt of peak output power.As such,this technology would represent at least a .ve-fold improvement over photovoltaic technology interms of cost.A simple estimate of energy cost using the proposed technology based on an averageof only four hours per day of operation over a modest ten year lifetime indicates a cost of about$0.066/kW-hr.Although not equal to the lowest costs for electricity,this is certainly an energycost that makes the technology very valuable when considering the additional advantages of itsnature.Namely,this is a distributed renewable energy source with an availability that is fairly wellmatched to peak demand times.Further,this technology is well suited to distributed deploymentin an analogous manner to that of photovoltaic generation.As such,it will be valuable for remotesites where utility infrastructure is non-existent or too costly as well as for residential and businesssites as an alternative to photovoltaics.The PI has been active in integrating research into new and existing classes,and plans to con-tinue this in conjunction with the proposed work.The PI also actively seeks to include underrep-resented student groups in his projects.UC Berkeley hosts the SUPERB (Summer UndergraduateProgram in Engineering Research at Berkeley,http://www.coe.berkeley.edu/cues/superb/index.html)program which targets underrepresented and minority students.The PI plans to actively recruitin the SUPERB program for students to participate in the proposed project during the summerperiods.Intellectual Merit A direct strategy for enabling a renewable energy source by seeking to min-imize the cost-to-output-power ratio is outlined.We analyze the cost of an integrated systemincluding a solar thermal collector and a low-temperature Stirling engine.Novel multi-phase free-piston Stirling machine designs are proposed along with rigorous analysis techniques for their designand evaluation.Speci .cally,a Stirling machine with no mechanical linkages and only three movingparts is discussed.This is a design that inherently permits for a long maintenance-free lifetime andfor very low frictional losses.1