Sources of Energy
Since the invention of the steam engine, humans have relied more and more on nonrenewable sources of energy, especially coal, petroleum, and natural gas; the reserves of which are limited. To a lesser extent, they have made use of renewable resources, such as water power from rivers to produce electricity, which nevertheless comes at a cost to the environment. Thus, one of the greatest challenges of today is how to obtain energy in an economical, safe, and clean way from renewable sources. Besides the importance of availability, the impact that sources of energy produce on the environment counts a great deal. The nonrenewable sources of energy coal, petroleum, and natural gas make up eighty-one percent of the world’s production of energy. Their consumption on such a massive scale contributes to the greenhouse effect.
Industrial Plant in the Daylight
Gasoline or diesel with added alcohol (ethanol) produced from crops such as corn appears more and more promising as solutions to the problems posed by the eventual exhaustion of the Earth’s coal and petroleum reserves, as well as the high cost of fossil fuels on the global markets. However, this type of energy presents new challenges. One item of environmental concern is the possibility that massive exploitation of biofuels could lead to the replacement of jungles and woodlands with single crop plantations meant only for the production of raw plant materials. Ethanol is the alcohol in the medicine cabinets of our homes. It can be used in its pure form as fuel or combined with gasoline in different proportions. Two common mixtures are E10 and E85, which have 10 percent and 85 percent ethanol, respectively. 70 percent of the world’s ethanol production is accounted for by Brazil and the United States. In Brazil, ethanol is made from sugarcane, and in the USA, it is made from corn.
The Anaerobic Lagoon at the Cal Poly Dairy 25KW Power Plant to the Right Using the Biogas Created
To achieve the breakdown of the nucleus, the neutrons must collide at a specific speed, which is governed by a moderating substance, such as water, heavy water, or graphite. The purpose of nuclear fission is to create very hot steam to operate turbines and electrical generators. The high temperatures are achieved by using nuclear energy from the reactor. Although this technology has been used for half a century, it continues to be at the center of debate because of the risks it poses to the environment and health and because of the vast amounts of highly toxic waste it creates.
Aerial view of Hoover Dam Showing Four Intake Towers which Gradually Funnel Water Towards the Powerhouse
Once the circuit is closed, there is a constant flow of electrons (electric current) from the negative terminal to the positive one. The current is maintained as long as the Sun illuminates the cell.
Another use of sunlight is as a source for heating water as well as for heating homes. In this case, solar collectors are used; unlike photovoltaic cells, the solar collectors do not produce electric energy. The collectors work using the greenhouse effect: It absorbs the heat from the sun and then prevents this heat from being lost. In doing so, it warms a pipe, through which the fluid (water or gas) flows, which in turn heats a water tank. The water from the tank is ready for domestic use of heating.
The by-products of the process are water and heat, the reaction continues as long as fuel is supplied. Among the advantages of hydrogen-based energy are its very low pollution level and its inexhaustibility (it can be recycled and reused.) Disadvantages include the complications inherent in handling pure hydrogen, its costs, and the wide-scale conversion that would be necessary for petroleum-fueled engines and systems.