Solar Stirling engine has advantages over CSP technology
which also collects the sun’s heat. Most CSP systems need
water, which is tough in desert regions, while Stirling engines
need nothing other than cleaning the mirrors . In DSE
systems, if one engine goes down, it has negligible effect on overall production. But in tower CSP technology, which doesn’t generate electricity until the whole system is complete. Tower CSP technology has less efficiency as compared to the DSE.
Comparison With Solar Thermoelectricity
According to the University of Pacific one thermoelectric module is capable of producing 14 watts of electrical power and its cost is approximately $100. The efficiency of TEG is 5-8% which is very low as compare to the DSE. Although its size is smaller than Stirling engine. TEG is made of Bismuth telluride which is toxic and expensive.
Comparison With Parabolic Trough Table
The efficiency of the Parabolic trough is 14-20%
which is very less as compare to DSE.
Parabolic trough is shown in figure .
Advantages of Stirling Engine.
Sterling engine is almost impossible to blast. You do not have to generate steam in a high pressure boiler. And inside the cylinder there are no explosions needed to run the pistons like in an internal combustion engine. There are no ignitions because you require only one kind of gas and no valve train because there are no valves. This was a big advantage to the steam engines in the days when Sterling invented his engine
because it was much less dangerous to work next to a Sterling Engine than to a common steam engine.
Inside the pistons can be used air, He, N2 or H and you don’t have to refill it because it uses always the same body of gas. The external combustion process can be designed as a continuous process, so the most types of emissions can be condensed. If heat is available from a renewable energy source they produce no emissions. They run very silent and they don’t need any air supply.
They can be constructed to run very silent and practically without any vibration. They can operate with a small temperature difference, e.g. with the heat of hand or from a cup of hot coffee. They can be used as small engines for work which desires only low power.
Comparison Between Solar Dish Stirling Engine And Other Solar Techniques
The Pakistan residential house uses 220 AC voltage electricity but PV cells produce direct current (DC) voltage. Therefore we have required a DC to AC inverter which convert the DC voltage into AC voltage which is usable for the house. But the sterling engine can produce electricity at 220 VAC directly and also at 50 HZ. Therefore output can be fed directly to the power grid. Multijunction PV cells that have higher energy transferring efficiency as compared to silicon PV cells, are usually made of poisonous material like cadmium tellur
From our results and comparisons we conclude that solar Stirling system is more efficient than other solar techniques. Its efficiency is about 32 percent. Life span of Stirling engine is 25 years. It can operate on any heat source other than sun so we can use it for generation purpose 24 hours which make it more reliable. Its maintenance cost is very low. We also conclude that capital cost of solar Stirling system is high but the source of energy is free till the universe ends. It is most efficient renewable energy technique as compare to other renewable energy techniques like (PV system, TEG, CSP tower).
The Technique Dish Stirling engine System is ecofriendly and has more efficiency than other renewable techniques. Due to this it must be more installed in near future. To overcome energy crisis in Pakistan we have to employ such renewable techniques. It could be more efficient by using parabolic mirror.