alternative energy sources and technologies process design and operation pdf

Alternative Energy Sources And Technologies Process Design And Operation Pdf

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Alternative Energy

Steven Winter Associates, Inc. While the large majority of energy used in the United States still comes from fossil fuels see EIA for example , there is also tremendous growth in alternative and renewable energy technologies. In this context, alternative energy refers to energy not derived from traditional fossil fuel sources coal, natural gas, petroleum through conventional processes.

Renewable energy is a subset of alternative energy; according to the National Renewable Energy Laboratory NREL , "Renewable energy resources—such as wind and solar energy-are constantly replenished and will never run out. Both market and regulatory forces are driving increased adoption of renewable energy. To stimulate development of new renewable energy projects, Executive Order requires federal agencies to explore on-site renewable energy generation at their facilities. Many states around the nation have implemented renewable portfolio standards RPS mandating a minimum fraction of renewably generated energy in all electricity sold.

In conjunction with regulatory requirements for renewable energy, costs of fossil fuels remain rather high and costs of some renewable and alternative energy technologies are coming down. This article focuses on several such energy sources, with a primary focus on electricity generation. The practical use of these systems varies with the specific technology, application, location, cost of energy, and other factors.

While many of the technologies are becoming more cost-effective , alternative energy generation is not a substitute for reliable energy efficiency strategies. Implementing efficiency strategies first is still the best approach to meet most energy goals. For centuries, people have harnessed energy in the wind—historically this has been used as mechanical energy for milling or water pumping.

Wind-powered water pumps are still used in remote areas of the U. In modern wind turbines , kinetic energy in the wind is converted to rotational energy and then to electrical energy. This electricity is then conditioned and—in most cases—sent into the utility grid. In some parts of the country, wind energy has become cost-competitive with conventional sources of electricity generation.

There are a growing number of wind generators available with capacities ranging from a few hundred watts powering small off-grid homes, sailboats, etc. Wind generators are certainly most effective in areas with consistent, high-speed winds. Trees, buildings, and topography can slow winds down tremendously.

In the United States, the best wind resources are generally near the coasts off-shore or on the Plains. DOE, NREL, and others have developed wind resource maps for the country and some states have developed more detailed maps. Proper location of wind turbines is critical. Because there can be wide variations in wind speed over small distances, best practices often call for monitoring wind resources at a site or several potential sites for a year or more.

With smaller generators several kilowatts , turbines should typically be mounted 30—50 feet above the next highest object in a foot radius trees, buildings, etc. Larger generators are centered feet or more off the ground where wind speeds are higher and less turbulent. Because most electric energy is used in buildings, many people have explored mounting wind turbines on top of buildings. This is often not a viable strategy because of the weight, vibrations, torque, and noise of the generators.

To get access to higher wind speeds, generators should be positioned well above nearby buildings. There are some wind generator products, however, specifically designed for mounting on buildings.

They are usually small typically Watts or less and are still subject to wind speed and turbulence limitations. While small, building-mounted turbines can be appealing to designers, larger turbines located far above buildings and other obstructions are much more effective with respect to electricity generation. Biomass power generation typically refers to the combustion of plant material to power turbines which—in turn—generate electricity. The term biofuel generally refers to a fuel derived from plant material biomass that can be used in lieu of conventional fossil fuels.

The oldest use of biomass energy is burning wood to keep warm. This is still quite common in homes today, and there are also more advanced boiler systems that burn wood to heat water for use in homes or larger buildings. Some of these devices are designed to burn wood pellets rather than larger pieces of wood. Wood pellets are small less than one inch pieces of processed biomass from a variety of sources wood chips, sawdust, waste from wood processing, etc.

Pellet-burning appliances typically have hoppers that feed the fuel to the firebox at a controlled rate—making pellet burning easier to control than some other types of biomass appliances.

GOV Energy Saver pages. On larger scales, many timber and agricultural industries burn wood and agricultural waste to obtain useful heat—the heat can be used directly or used to power turbines to generate electricity. When the biomass fuel is inexpensive—especially when it is a waste product—such power generation can be very cost-effective.

As with burning of fossil fuels, burning biomass releases carbon dioxide and other pollutants. Because the carbon in biomass has quite recently been absorbed from the atmosphere, if the biomass resource is managed sustainably there may be little net-emissions of carbon dioxide. This closed carbon cycle, however, does not necessarily include any energy needed to cultivate, harvest, and process the biomass.

In addition to pollutants, opponents of biomass generation cite potential effects on regional agriculture or forestry. With growing demand for biomass, there may be pressure to harvest resources in less sustainable ways.

As described above, biofuels are fuels derived from biomass that can be used in place of conventional fossil fuels. The two most common biofuels are ethanol and biodiesel. Ethanol is currently used in gasoline mixtures to power many automobiles. Most of this ethanol comes from the fermentation of sugars found in food crops, primarily corn. Federal incentives make this cost-effective, but there is growing concern that using ethanol derived from fermentation of corn sugars is not sustainable; there may be more energy needed to cultivate, harvest, and process the material than is contained in the final fuel produced.

Other ethanol production strategies—using cellulosic material rather than sugars—can derive ethanol from wood chips, leaves, agricultural waste, and similar material.

Biodiesel is made by converting natural oils—usually vegetable oils—into usable fuels. The fuel can be used in many engines or combustion appliances designed for diesel or no.

The appliances typically need no or minor adjustments, though sometimes a blend of biodiesel and petroleum results in best operation. The manufacturing process is well understood and quite environmentally benign. The chief limitation of biodiesel manufacture is a cost-effective , sustainable source of vegetable oils. Waste oils were one of the first targets for biodiesel manufacturers. In some areas, restaurant managers—who used to pay substantial fees to dispose of waste cooking oils—found new consumers who were willing to take waste oil at no charge, or even to pay for the used oil.

While truly sustainable, such waste oil results in a very small volume of biodiesel. Most fuel is generated from virgin vegetable oils, especially oils from soy or rapeseed. Most experts agree that biodiesel manufacture is much less energy-intensive than conventional ethanol production—i. Solar energy systems in buildings include systems that capture heat such as solar water heating systems and passive heating , and systems that convert solar energy into electricity.

The latter is done primarily through photovoltaic PV systems. PV technology has seen dramatic improvements—and cost reductions—since its first applications in the space program in the 's. The heart of PV technology is in the semi-conductors mostly silicon-based used in the PV modules themselves.

The modules convert sunlight to direct current DC energy; the DC energy is typically then converted to alternating current AC energy via inverters. From the inverters, energy is typically fed into a building's electric system or exported to the utility grid. Simple schematic showing the main components of a PV system and how it is typically incorporated into a building—in this case a home.

The amount of electricity that a PV system generates depends upon the amount of sun received and many other installation parameters tilt, orientation, shading, etc. As PV collectors need direct sun, they are often mounted on roofs. While not extremely heavy, structural factors must be taken into account in planning a roof-top installation. Designers need to be aware of mounting requirements, ballast, and wind loads.

Any roof penetrations for mounting or electrical need to be planned for and detailed properly. Panels should face south in the northern hemisphere and shade from trees, other buildings, roof-top equipment, etc. In some cases, PV collectors can be incorporated as part of the roof or building envelope; see the Building-Integrated Photovoltaics page for more information.

While most PV collectors are mounted in stationary positions, some free-standing arrays use devices to track the path of the sun across the sky.

PV modules themselves are very durable and have no moving parts; most warrantees are 20—30 years. Inverters are usually shorter-lived; these warrantees are typically 5—10 years. PV system on a mail processing center in Los Angeles. PVs are one of the most reliable renewable energy technologies, and building integration can be straightforward. Photo Credit: Bill Golove. PVs can also be mounted on the ground or auxiliary structures. In a few locations, these high temperatures reach closer to the surface resulting in volcanic activity, hot springs, geysers, and the opportunity for geothermal electricity generation.

Geothermal plants tap relatively shallow pockets of steam; the steam is used to operate turbines that generate electricity. Clearly, geothermal generation is very location dependent. According to Department of Energy sources, there is approximately 3, MW of geothermal electricity generation capacity in the United States. Researchers say, however, that there is potential for , MW of generation using the latest technologies.

At some locations where the accessible geothermal resources are not at sufficient temperature to generate electricity cost-effectively, the heat can be used directly for industrial processes, space heating, etc. In the United States, nearly all generators—and most potential sites—are located in the western part of the country see map.

The term "geothermal" is also sometimes used to refer to ground source heat pumps GSHPs. When a fuel—fossil-based or otherwise—is converted to electricity, there is also a substantial amount of heat generated. Cogeneration or combined heat and power CHP is a strategy whereby both useful heat and electricity are obtained from processing a fuel. These cogeneration units provide electricity to meet some of the base load in a New York City apartment building.

While the up-front and maintenance costs are significant, the cost of the natural gas used to generate electricity is less than the cost of electricity purchased from the utility.

The concept itself is not new. For nearly as long as people have been burning fuel to generate electricity, people have been looking for ways to utilize the excess heat generated. Newer technologies, combined with higher energy rates, allow smaller-scale, distributed cogeneration to be more cost effective in some buildings or campuses.

Sustainable energy

Steven Winter Associates, Inc. While the large majority of energy used in the United States still comes from fossil fuels see EIA for example , there is also tremendous growth in alternative and renewable energy technologies. In this context, alternative energy refers to energy not derived from traditional fossil fuel sources coal, natural gas, petroleum through conventional processes. Renewable energy is a subset of alternative energy; according to the National Renewable Energy Laboratory NREL , "Renewable energy resources—such as wind and solar energy-are constantly replenished and will never run out. Both market and regulatory forces are driving increased adoption of renewable energy. To stimulate development of new renewable energy projects, Executive Order requires federal agencies to explore on-site renewable energy generation at their facilities. Many states around the nation have implemented renewable portfolio standards RPS mandating a minimum fraction of renewably generated energy in all electricity sold.

The limitation of fossil fuels has challenged scientists and engineers to search for alternative energy resources that can meet future energy demand. Renewable Energy System Design is a valuable reference focusing on engineering, design, and operating principles that engineers can follow in order to successfully design more robust and efficient renewable energy systems. Written by Dr. It explores renewable energy storage devices with an emphasis on batteries and fuel cells and emerging sustainable technologies like biomass, geothermal power, ocean thermal energy conversion, solar thermal, and satellite power. Renewable Energy System Design is a must-have resource that provides engineers and students with a comprehensive yet practical guide to the characteristics, principles of operation, and power potential of the most prevalent renewable energy systems. Engineers, project managers, consultants and students working in and studying Renewable Energy development and implementation.

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For Sustainable Development: Future Trends in Renewable Energy and Enabling Technologies

Energy demand in the world is nowadays growing further out of limits of installable generation capacity. Therefore, future energy demands should be met and improved efficiently and securely. Energy solutions should be supported by utilizing renewable energy sources. At present, the contribution of renewable energy to the world primary energy is not high to meet the primary energy and electricity supplies. Both developed and developing nations will necessarily continue to rely on fossil fuels in the coming decades.

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Sustainable energy is energy produced and used in such a way that it "meets the needs of the present without compromising the ability of future generations to meet their own needs. The energy transition to meet the world's needs for electricity, heating, cooling, and power for transport in a sustainable way is widely considered to be one of the greatest challenges facing humanity in the 21st century. Worldwide, nearly a billion people lack access to electricity , and around 3 billion rely on smoky fuels such as wood, charcoal or animal dung to cook. Air pollution from fossil fuels is estimated to cause 3 million deaths each year, and air pollution from use of dirty cooking fuels is estimated to cause around 4 million deaths each year.

Alternative Energy

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Conventional energy source based on coal, gas, and oil are very much helpful for the improvement in the economy of a country, but on the other hand, some bad impacts of these resources in the environment have bound us to use these resources within some limit and turned our thinking toward the renewable energy resources. The social, environmental, and economical problems can be omitted by use of renewable energy sources, because these resources are considered as environment-friendly, having no or little emission of exhaust and poisonous gases like carbon dioxide, carbon monooxide, sulfur dioxide, etc. Renewable energy is going to be an important source for power generation in near future, because we can use these resources again and again to produce useful energy. Wind power generation is considered as having lowest water consumption, lowest relative greenhouse gas emission, and most favorable social impacts. It is considered as one of the most sustainable renewable energy sources, followed by hydropower, photovoltaic, and then geothermal. As these resources are considered as clean energy resources, they can be helpful for the mitigation of greenhouse effect and global warming effect. Local employment, better health, job opportunities, job creation, consumer choice, improvement of life standard, social bonds creation, income development, demographic impacts, social bonds creation, and community development can be achieved by the proper usage of renewable energy system.

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