Energy Development

Energy Options Fossil Energy

The literature contains several publications that present a description of the energy sources that are available or are expected to be available during the 21st century. Energy options known today include fossil fuels, nuclear energy, solar energy, renewable energy and alternative sources. These energy options are briefly described in the chapters that follow. Fossil fuels are sources of energy that were formed by the death, decay, and transformation, or diagenesis, of life. The term diagenesis...

Solar Power Tower

Solar Elec Power Tower

Figure 4-8 is a sketch of a solar power tower with a heliostat field. The heliostat field is a field of large, Sun-tracking mirrors called heliostats arranged in rings around a central receiver tower. The heliostats concentrate sunlight on a receiver at the top of the tower. The solar energy heats a fluid inside the receiver. Figure 4-9 is a sketch of the geometry of the Sun-tracking mirrors relative to the central receiving station. The heliostats must be able to rotate to optimize the...

Roof Overhang

Sunlight that strikes the surface of an object and causes an increase in temperature of the object is an example of direct solar heat. Direct solar heating can cause an increase in temperature of the interior of buildings with windows. The windows that allow in the most sunlight are facing south in the northern hemisphere and facing north in the southern hemisphere. Figure 4-4 illustrates two seasonal cases. The figure shows that the maximum height of the Sun in the sky varies from season to...

Household Circuits

Households are among the most common consumers of electricity in the modern world. Electricity is delivered as alternating current to a typical house in the United States using either a two-wire line, or a three-wire line. The potential difference, or root mean square voltage, between the two wires in the two-wire line in the United States is 120 volts, and is 240 volts in many parts of Europe. One of the wires in the two-wire line is connected to a ground at the transformer and the other wire...

Forecasts Schollnberger Energy

Forecasts of the 21st century energy mix show that a range of scenarios is possible. The forecast discussed here is based on W.E. Schollnberger's forecasts, which were designed to predict the contribution of a variety of energy sources to the 21st century energy portfolio. Schollnberger's forecast is worth studying because it uses more than one scenario to project energy consumption for the entire 21st century. Schollnberger considered the following three forecast scenarios A. Another Century...

Renewable Energy And The Environment

The environmental impact of some clean energy sources is Hydroelectric facilities, notably dams, can flood vast areas of land. The flooded areas can displace people and wildlife, and impact the ecosystems of adjacent areas with consequences that may be difficult to predict. Dams can change the composition of river water downstream of the dam and can deprive land areas of a supply of silt for agricultural purposes. A dam on a river can prevent the upstream migration of certain species of fish,...

Brief History Of Energy Consumption

Emergence Agriculture Circa 5000

We decide how much electricity we will use to heat or cool our homes. We decide how far we will drive every day and the type of vehicle we will drive. Those of us in democracies choose leaders who create budgets that can support new energy initiatives or maintain a military capable of defending energy supply lines. Each of these decisions and many others impact the global consumption of energy and the demand for available natural resources. The purpose of...

Solar Heat Collectors

Infrared Collector

Solar heat collectors capture sunlight and transform radiant energy into heat energy. Figure 4-6 is a diagram of a solar heat collector. Sunlight enters the collector through a window made of a material like glass or plastic. The window is designed to take advantage of the observation that sunlight is electromagnetic radiation with a distribution of frequencies. The window in a solar heat collector is transparent to incident solar radiation and opaque to infrared radiation. The heat absorber...

Biomass Conversion

Biomass, particularly biological waste, appears to be a plentiful source of methane. A simple methane digester that converts biological feed such as dung to methane is shown in Figure 6-5. The screw agitator mixes the liquid slurry containing the feed. The mixing action facilitates the release of methane from the decaying biomass as a biomass conversion process. Methane trapped by the metal dome is recovered through the gas outlet. containing the feed. The mixing action facilitates the release...

Point to Ponder Are synfuels desirable alternative energy sources

Like biomass and fossil fuels, synfuels provide energy by generating heat using combustion. Once again the combustion process produces carbon dioxide as a byproduct. Carbon dioxide is a greenhouse gas and sequestration becomes an issue. Sequestration is the capture and storing of greenhouse gases. For example, we can geologically sequester carbon dioxide by injecting it into a geologic formation such as a coal seam or an abandoned oil field. Unlike biomass, coal gasification and gas-to-liquid...

The Hydrogen Economy

The historical trend toward decarbonization reflects the contention by many energy forecasters that hydrogen will be the fuel of choice in the future. These forecasters believe that power plants and motor vehicles will run on hydrogen. The economies that emerge will depend on hydrogen and are called hydrogen economies. The concept of a hydrogen economy is not new. The use of hydrogen as a significant fuel source driving a national economy was first explored in the middle of the 20th century as...

Electric Power Generation

The first commercial-scale electric power plants were hydroelectric plants. The primary energy source, or the energy that is used to operate an electricity-generating power plant, is flowing water for a hydroelectric plant. Today, most electricity is generated by one of the following primary energy sources coal, natural gas, oil, or nuclear. Table 8-2 presents the consumption of primary energy in the year 1999 as a percentage of total primary energy consumption in the world for a selection of...

Waves and Tides

The oceans are another solar-powered source of energy. The mechanical energy associated with waves and tides, and thermal energy associated with temperature gradients in the ocean can be used to drive electric generators. We consider each of these energy sources in this section. In our discussion of hydropower, we saw that water can generate power when it moves from a high potential energy state to a low potential energy state, like water flowing over a waterfall. If the moving water is an...

Active Solar Energy

Active Solar Energy

Active solar energy refers to the design and construction of systems that collect and convert solar energy into other forms of energy such as heat and electrical energy. Active solar energy technologies are typically mechanical systems through a material. Metals have relatively high thermal conductivities. Heat Flow through Wall Figure 4-5. Thermal Conductivity of an Insulated Wall that are used to collect and concentrate solar energy. We will discuss solar heat collectors and a solar power...

Point to Ponder Why arent solar power plants more popular in sunny deserted areas

One of the major advantages of solar power plants is that the energy is free. There are, however, several issues to consider that impact cost and social acceptability. The free energy from the Sun has to be collected and transformed into commercially useful energy. Solar power plants to date cover the area of several football fields and produce approximately 1 of the power associated with a fossil fuel fired power plant. This means that solar power plants will cover relatively large areas and...

Steam Generated Power

Ore is rock that contains metals such as copper, tin, iron, and uranium. Heat from fire frees the metal atoms and allows them to be collected in a purified state. Copper and tin were the first metals smelted and could be combined to form bronze. Heat and water were combined to generate steam and steam engines were developed to convert thermal energy to mechanical energy. Early steam engines drove a piston that was placed between condensing steam and air, as...

Energy Options Solar Energy

Renewable energy is energy obtained from sources at a rate that is less than or equal to the rate at which the source is replenished. In the case of solar energy, we can only use the energy that is provided by the Sun. Since the remaining lifetime of the Sun is measured in millions of years, many people consider solar energy an inexhaustible supply of energy. In fact, solar energy from the Sun is finite, but should be available for use by many generations of people. Solar energy is therefore...

Photovoltaics

Photovoltaics is an application of the photoelectric effect. We can describe photovoltaics as the use of light to generate electrical current. We can make a photovoltaic cell, or photocell, by placing two semi-conductors in contact with each other. Light shining on the photocell expels electrons that can travel from one semi-conductor to the other. Photocells are not sources of energy and they do not store energy. Photocells transform sunlight into electrical energy. When sunlight is removed,...

History of Nuclear Power

Physicist Leo Szilard conceived of a neutron chain reaction in 1934. Szilard knew that neutrons could interact with radioactive materials to create more neutrons. If the density of the radioactive material and the number of neutrons were large enough, a chain reaction could occur. Szilard thought of two applications of the neutron chain reaction a peaceful harnessing of the reaction for the production of consumable energy and an uncontrolled release of energy (an explosion) for military...

Hydrogen An Energy Carrier

Hydrogen is found almost everywhere on the surface of the Earth as a component of water (Figure 7-1). It has many commercial uses, including ammonia production for use in fertilizers, methanol production, hydrochloric acid production, and use as a rocket fuel. Liquid hydrogen is used in cryogenics and superconductivity. Hydrogen is important to us because it can be used as a fuel. Hydrogen can be used as a fuel for a modified internal combustion engine or in a fuel cell. Fuel cells are...

Wind Turbine

Modern wind turbines are classified as either horizontal axis turbines or vertical axis turbines. A vertical axis turbine has blades that rotate around a vertical axis and its visual appearance has been likened to an eggbeater. A horizontal axis turbine has blades that rotate around a horizontal axis (see Figure 5-1). Horizontal axis turbines are the most common turbines in use today. A typical horizontal axis turbine consists of a rotor with two or more blades attached to a machine cabin set...

Point to Ponder Can we put the nuclear genie back in the bottle

Some historians argue that nuclear weapons were not needed to end World War II and that the world would be better off if nuclear energy had never been developed. Today, a nation with a nuclear weapons arsenal must be concerned about the security of every weapon in its arsenal. Even one nuclear weapon can be a weapon of mass destruction. In addition, many nations are seeking to acquire nuclear technology, which increases the risk of nuclear weapons proliferation. Now that the world knows about...

Nuclear Winter

One of the more controversial issues associated with the climatic effects of nuclear fallout is the concept of nuclear winter. Nuclear winter is the prediction of significant climatic temperature declines resulting from an increase of atmospheric particulates following the detonation of many nuclear weapons in the atmosphere. The temperature decline would generate wintry conditions, hence the phrase nuclear winter. In the nuclear winter scenario, the temperature of the atmosphere is expected to...

Point to Ponder What are some current uses of photovoltaics

There are many applications of photovoltaics. They include solar powered calculators, solar powered camping equipment, solar powered satellites, the International Space Station, and solar powered cars. A solar powered traffic system for helping enforce speed limit laws is shown in Figure 4-11. Figure 4-11. Solar Powered Traffic Control, Golden, Colorado Figure 4-11. Solar Powered Traffic Control, Golden, Colorado

Source of Solar Energy

Solar energy is energy emitted by a star. Figure 4-1 shows the anatomy of a star. Energy emitted by a star is generated by nuclear fusion. The fusion process occurs in the core, or center, of the star. Energy released by the fusion process propagates away from the core by radiating from one atom to another in the radiation zone of the star. As the energy moves away from the core and passes through the radiation zone, it reaches the part of the star where energy continues its journey towards the...

Availability of Nuclear Fuel

The most abundant fuel for nuclear fission is uranium. Uranium exists in the crust of the Earth as the mineral uraninite. Uraninite is commonly called pitchblende and is a uranium oxide (U3O8). It is found in veins in granites and other igneous rocks. It is possible to find uranium in sedimentary rocks. In this case, scientists believe that uraninite was precipitated in sedimentary rocks after being transported from igneous rocks by the flow of water containing dissolved uraninite. Uranium is...

Point to Ponder Can distributed generation increase the usefulness of wind and solar energy

We have noted previously that energy from wind and sunshine is not always produced when it is needed. The Sun does not shine on a particular spot on the surface of the Earth all day long, but the Sun does shine all the time. We can use sunlight 24 hours per day if we can collect sunlight at different locations around the globe. Similarly, the wind does not usually blow all the time at a particular location, but wind is always blowing somewhere. Distributed generation can be used to harvest both...

Geothermal Heat Pump

A geothermal heat pump uses energy near the surface of the Earth to heat and cool buildings. The temperature of the upper three meters (10 feet) of the Earth's crust remains in the relatively constant range of 10 Centigrade to 16 Centigrade. A geothermal heat pump for a building consists of ductwork in the building connected through a heat exchanger to pipes buried in the shallow ground nearby. The building can be heated during the winter by pumping water through the geothermal heat pump. The...

Energy Options Nuclear Energy

Nuclear energy is presently provided by nuclear fission. Nuclear fission is the process in which a large, unstable nucleus splits into two smaller fragments. It depends on a finite supply of fissionable material. Nuclear fusion is the combination, or fusing, of two small nuclei into a single larger nucleus. Many scientists expect nuclear energy to be provided by nuclear fusion sometime during the 21st century. Fusion reactions are the source of energy supplied by the Sun. Attempts to harness...