Given society's ever increasing energy consumption, there is a resultant high demand for energy. Since the earth's natural energy reserves are becoming depleted and prices of oil and natural gas are relatively high, there is a demand for new sources of energy.
There have been attempts to convert existing forms of energy into forms of energy that can be used to satisfy our energy needs. Many of these processes harness energy sources that are replenished by natural processes. These energy sources are referred to as renewable energy sources. An example is solar energy where energy from the sun in the form of heat energy and light energy is converted into electrical energy. However, sunlight is a weak energy source compared to traditional energy sources such as fossil fuels. It is very difficult to harness sunlight efficiently for conversion into useful forms of energy. It is particularly difficult to use sunlight effectively for home energy needs. Energy requirements are usually highest when it is dark and cold. This is precisely when solar energy is least effective. Solar energy becomes much more useful when we change it to another form. Sunlight can be converted to electricity by photovoltaic cells. However, this conversion is inefficient and high in cost. Also, some types of photovoltaic solar cells contain mercury that is highly toxic.
Other renewable energy sources have the drawback of being environmentally unfriendly. For example, wind power plants can damage local animal populations. Also, hydroelectric dams can cause problems such as the creation of large reservoirs. This can upset the ecological balance of the surrounding environment. This has the consequences of disrupting local animal populations and their migration patterns. Dams also affect fish populations.
It would therefore be desirable to be able to harness existing forms of energy in an effective and environmentally friendly manner. It has been recognized that it would be desirable to convert naturally occurring heat sources into useable forms of energy. There have been a number of attempts to convert low-level heat sources into mechanical energy. These methods employ the principle of expansion and contraction of a working fluid, utilizing a heat source to add and remove heat from the working fluid. These methods have the drawback of failing to obtain a sufficient concentration of heat to activate the process in an efficient manner. Such methods to date have failed to produce an economically viable energy generation process.
U.S. Pat. No. 4,134,265 provides an example of such a prior art process. This patent discloses a method for developing gas pressure to drive an engine. The method involves the use of a plurality of separate containers in a closed circuit. The tanks communicate with heat exchangers that are arranged in combination with certain controls to create pressure variations on a given volume of gas by varying the gas temperatures. The tanks are used in pairs with the gas in one tank being cooled while the other gas in the other tank is heated to develop a pressure differential therebetween. Controlled communication between the tanks produces flow to one of the tanks with an increase in mass of gas therein and followed by a second development of gas differential pressure. The gas is released for communication with a piston to produce a work stroke.
U.S. Pat. No. 3,995,429 provides another example of a prior art process that fails to produce an economically viable energy generation system. The patent discloses a system of generating electric power derived from the energy of the sun, the atmosphere, the ground or the heat stored in ground water, whichever provides the greatest temperature differential with another adjacent source of energy. The apparatus generates a fluid vapour pressure for the operation of a vapour engine and includes at least three heat sources. One of the sources is a solar absorber for absorbing the heat from the sun. A second source is a heat exchanger which dissipates the heat of the fluid to the atmosphere. A third source is a radiator positioned in the ground water. A fourth source for transforming ground or geothermal heat to the fluid also for transferring the heat of the ground water to the fluid is provided. Other well-known heat sources may be substituted where available. Valve connecting means are operated to connect any two of the four heat sources in a closed cycle system for the transfer of heat from one source to another. Pumping means are provided for forcing fluid through the system to a source where the fluid is vaporized. A transducer such as a turbine or piston engine connected to the heat source vaporizes the fluid that produces the mechanical power.
There have been attempts to harness naturally occurring temperature gradients. An example is Ocean Thermal Energy Conversion. A significant amount of financial resources have been invested in pilot plants to harness the surface heat of the world's oceans by making use of temperature gradients between the warm surface and cold depths. This has not yielded an economically viable method for energy production.
There is therefore a need for an apparatus and method for converting thermal energy into mechanical and electrical energy in an environmentally friendly efficient, and economically viable manner. There is a need for such an apparatus and method that can utilize a very low temperature differential to produce energy efficiently.