Zaragoza University is doing a lot of work on the Stirling Dish.

 

                                     

This is is a heat engine powered by a temperature gradient generated by the sun it links a heat engine, such as a Stirling cycle engine, with a solar dish collector in order to produce electricity..This apparatus consists of a large dish aimed at the sun to reflect the rays into the focus point, which is located at the center of the dish. Solar energy is then collected in the form of heat to fuel a Stirling cycle engine,  which operates by letting heat flow from a hot source to a cold sink in order to do work. The work output of the Stirling cycle is then used to drive a generator and create electric power. Moreover, in Meijer’s solar-powered engine, it is important that the dish always be pointed directly at the sun so that no shadows would be present in the solar dish collector, hence optimizing heat collection. This is where he ran into some issues because, in order for the apparatus to have a complete range of motion, lubrication and rotational systems would be necessary and may compromise structural stability.

A second type of solar-powered Stirling engine was patented by NASA on August 3, 1976 which employed the use of solar energy in order to freely pump water from a river, lake, or stream. The purpose of this apparatus is to “provide a low-cost, low-technology pump having particular utility in irrigation systems employed in underdeveloped arid regions of the earth…[using] the basic principles of the Stirling heat engine 

Recently, a company called Sunvention Solar Energy created a device very similar to what NASA came up with in 1976 that can pump 100,000 gallons per day purely off of solar energy and usage of the Stirling cycle costing only US$1,250 This apparatus, much like the others, uses a large solar dish to collect heat from the sun creating a high temperature source and also employs the low temperature water it collects from a nearby stream as its low temperature source allowing for a great range in temperature which in turn allows for more work to be done The work done in Sunvention’s apparatus is used to pump the water into nearby crop fields allowing for a “low-cost, low-technology pump having particular utility in irrigation systems employed in underdeveloped arid regions of the earth”. 

 

How Solar Energy Works

 

Solar energy

You should be able to outline how solar energy is used to generate electricity and to produce hot water.

Solar cells

Solar cells are devices that convert light energy directly into electrical energy. You may have seen small solar cells in calculators. Larger arrays of solar cells are used to power road signs in remote areas, and even larger arrays are used to power satellites in orbit around Earth.

Solar panels

Solar panels do not generate electricity, but rather they heat up water. They are often located on the roofs of buildings where they can receive heat energy from the sun. The diagram outlines how they work.

Cold water is pumped up to the solar panel, there it heats up and is transferred to a storage tank.

A pump pushes cold water from the storage tank through pipes in the solar panel. The water is heated by heat energy from the sun and returns to the tank. In some systems, a conventional boiler may be used to increase the temperature of the water.

 

Advantages

Solar energy is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced.

Disadvantages

• Solar cells are expensive and inefficient, so the cost of their electricity is high.
• Solar panels may only produce very hot water in very sunny climates, and in cooler areas may need to be supplemented with a conventional boiler.
• Although warm water can be produced even on cloudy days, neither solar cells nor solar panels work at night.