In the past 40 years, the development of solar power has been a significant innovation in the area of energy production. Solar power has become a revolutionary alternative to conventional power sources like coal and hydropower without the negative environmental consequences. From nearly nonexistent in 1974 to ubiquitous in 2015, photovoltaic solar panels are becoming an increasingly prominent way to harness the energy of the sun.
Throughout history, many energy sources have been proposed and developed each with its advantages and consequences. The most economically viable energy sources often consume readily available resources at the expense of the environment. Coal is possibly most plentiful fossil fuel available, and has thus maintained the majority share of energy production in spite of the destruction of landscapes for mining and air quality from combustion. Hydropower taps the power of the sun using the hydrologic cycle and produces no harmful emissions, yet dams block the migration of fish and large reservoirs submerge entire habitats.
Solar power takes the lead when both energy cost and environmental consequences are taken into consideration. Solar installations can tap the most plentiful resource energy from the sun while utilizing unoccupied desert or roof space. The only drawback is the relatively high initial investment required for residential solar systems.
Although photovoltaic solar energy generation in becoming increasingly prominent in developed countries, the initial investment is often a limiting factor for less developed countries and communities in need of electricity. I would improve upon solar technology by examining a lowcost alternative form of solar electricity generation. This system would utilize thermal energy captured from the sun to generate electricity by creating a thermal gradient across a Peltier module. Although this may sound complex, the underlying principles are relatively simple, and the majority of required materials are readily available at low cost.
Although generation of electricity from radiant energy has been successfully achieved in large scale desert installations, where huge reflectors focus sunlight onto a single point to boil water and run steam generator, residential radiant energy collection has largely been relegated to heating water for household use. My idea aims to provide a low cost alternative to small scale photovoltaic solar panels for use in economically disadvantaged areas.
When a hose full of water is left out in the sun, the water accumulates thermal energy by absorbing radiant energy from the sun. This principle is commonly utilized by solar water heating systems, which utilize a black hose or special collector to maximize radiant energy absorption. My system would include a black hose installed on a roof in a pattern that would allow for maximum coverage while utilizing convection to create a current to circulate water through the hose in a closed loop. Instead of using the heat collected by the tube to heat water or space, the heated water will flow through a water block fixed to one side of a Peltier module. The other side of the Peltier module will be attached to a heatsink that radiates heat from that side into the atmosphere. The Peltier module acts as a thermoelectric generator that utilizes the difference in temperature between the water block and the heatsink to generate an electric current. When water in the tube heats up to above the temperature of the air, the Peltier chip will create an electric current that could be harnessed to power lights or other small appliances.
In addition to developing this system, I would also analyze the efficiency of this system in different configurations. The system may be enhanced by utilizing a more effective heat sink, such as a nearby stream or underground water tank. Using water as a heat sink would be particularly effective in regions where the air temperature is significantly warmer than the water temperature during the day. Maximizing the temperature difference between the hot and cold sides would maximize the electrical generation. Modifying the solar collector may also increase the efficiency of the system.
While this system may not be as efficient at converting solar energy into electricity as photovoltaic solar panels, the cost of black tubing and a Peltier module would be much less expensive. If successful, this system would set the stage for continued development lowcost alternative energy sources, and into increasing the efficiency of Peltier chip technology. Further development of this approach to solar electricity generation may provide a cost effective small scale energy solution for parts of the developing world, or remote locations, that are in need of low cost electricity.
Submitted by Jonathan Bush, who will be attending Arizona State University at the Polytechnic Campus beginning Fall 2015.