Archive for February, 2010
Renewable energy
Renewable energy sources worldwide at the end of 2006.
Renewable energy is energy generated from natural resources—such as sunlight, wind, rain, tides, and geothermal heat — which are renewable (naturally replenished). In 2006, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass, such as wood-burning.Hydroelectricity was the next largest renewable source, providing 3% (15% of global electricity generaiton), followed by solar hot water /heating, which contributed 1.3%. Modern technologies, such as geothermal energy, wind power, solar power and ocean energy together provided some 0.8% of final energy consumption.
Climate change concerns coupled with high oil prices, peak oil and increasing government support are driving increasing renewable energy legislation, incentives and commercialization.European Union leaders reached an agreement in principle in March 2007 that 20 percent of their nations’ energy should be produced from renewable fuels by 2020, as part of its drive to cut emissions of carbon dioxide, blamed in part for global warming. Investment capital flowing into renewable energy climbed from $80 billion in 2005 to a record $100 billion in 2006.
In responce to the G8’s call on the IEA for “guidance on how to achieve a clean, clever and competitive energy future”, the IEA reported that the replacement of current technology with renewable energy could help reduce CO2 emmisions by 50% by 2050, which they claim is of crucial importance because current policies are not sustainable.
Wind power is growing at the rate of 30 percent annually, with a worldwide installed capacity of over 100 GW, and is widely used in several European countries and the United States. The manufacturing output of the photovoltaics industry reached more than 2,000 MW in 2006, and photovoltaic (PV) power stations are particularly popular in Germany. Solar thermal power stations operate in the USA and Spain, and the largest of these is the 354 MW SEGS power plant in the Mojave Desert. The world’s largest geothermal power installation is The Gevsers in California, with a rated capacity of 750 MW. Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18 percent of the country’s automotive fuel. Ethanol fuel is also widely available in the USA.
While there are many large-scale renewable energy projects and production, renewable technologies are also suited to small off-grid applications, sometimes in rural and remote areas, where energy is often crucial in human development. Kenya has the world’s highest household solar ownership rate with roughly 30,000 small (20–100 watt) solar power systems sold per year.
Some renewable energy technologies are criticised for being intermittent or unsightly, yet the market is growing for many forms of renewable energy.
Main renewable energy technologies
Three energy sources
The majority of renewable energy technologies are directly or indirectly powered by the sun. The Earth-Atmosphere system is in equilibrium such that heat radiation into space is equal to incoming solar radiation, the resulting level of energy within the Earth-Atmosphere system can roughly be described as the Earth’s “climate.” The hydrosphere (water) absorbs a major fraction of the incoming radiation. Most radiation is absorbed at low latitudes around the equator, but this energy is dissipated around the globe in the form of winds and ocean currents. Wave motion may play a role in the process of transferring mechanical energy between the atmosphere and the ocean through wind stress. Solar energy is also responsible for the distribution of precipitation which is tapped by hydroelectric projects, and for the growth of plants used to create biofuels.
Renewable energy flows involve natural phenomena such as sunlight, wind, tides and geothermal heat, as the International Energy Agency explains:
“Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.”
Each of these sources has unique characteristics which influence how and where they are used.
Wind power
Vestas V80 wind turbines
Airflows can be used to run wind turbines. Modern wind turbines range from around 600 kW to 5 MW of rated power, although turbines with rated output of 1.5–3 MW have become the most common for commercial use; the power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically. Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms.
Since wind speed is not constant, a wind farm’s annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favourable sites. For example, a 1 megawatt turbine with a capacity factor of 35% will not produce 8,760 megawatt-hours in a year, but only 0.35×24x365 = 3,066 MWh, averaging to 0.35 MW. Online data is available for some locations and the capacity factor can be calculated from the yearly output.
Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand. This could require large amounts of land to be used for wind turbines, particularly in areas of higher wind resources. Offshore resources experience mean wind speeds of ~90% greater than that of land, so offshore resources could contribute substantially more energy. This number could also increase with higher altitude ground-based or airborne wind turbines.
Wind power is renewable and produces no greenhouse gases during operation, such as carbon dioxdie and methane.
Water power
Energy in water (in the form of kinetic energy, temperature differences or salinity gradients) can be harnessed and used. Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy.
One of 3 PELAMIS P-750 Ocean Wave Power engines in the harbour of Peniche/ Portugal.
There are many forms of water energy:
· Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams. Examples are the Grand Coulee Dam in Washington State and the Akosombo Dam in Ghana.
· Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as a Remote Area Power Supply (RAPS). There are many of these installations around the world, including several delivering around 50 kW in the Solomon Islands.
· Damless hydro systems derive kinetic energy from rivers and oceans without using a dam.
· Ocean energy describes all the technologies to harness energy from the ocean and the sea:
o Marine current power. Similar to tidal stream power, uses the kinetic energy of marine currents
o Ocean thermal energy conversion (OTEC) uses the temperature difference between the warmer surface of the ocean and the colder lower recesses. To this end, it employs a cyclic heat engine. OTEC has not been field-tested on a large scale.
o Tidal power captures energy from the tides. Two different principles for generating energy from the tides are used at the moment:
o Tidal motion in the vertical direction — Tides come in, raise water levels in a basin, and tides roll out. Around low tide, the water in the basin is discharged through a turbine, exploiting the stored potential energy.
o Tidal motion in the horizontal direction — Or tidal stream power. Using tidal stream generators, like wind turbines but then in a tidal stream. Due to the high density of water, about eight-hundred times the density of air, tidal currents can have a lot of kinetic energy. Several commercial prototypes have been build, and more are in development.
· Wave power uses the energy in waves. Wave power machines usually take the form of floating or neutrally buoyant structures which move relative to one another or to a fixed point. Wave power has now reached commercialization.
· Saline gradient power, or osmotic power, is the energy retrieved from the difference in the salt concentration between seawater and river water. Reverse electrodialysis (RED), and Pressure retarded osmosis (PRO) is in research and testing phase.
· Deep lake water cooling, although not technically an energy generation method, can save a lot of energy in summer. It uses submerged pipes as a heat sink for climate control systems. Lake-bottom water is a year-round local constant of about 4 °C.
Solar energy use
Monocrystalline solar cell
In this context, “solar energy” refers to energy that is collected from sunlight. Solar energy can be applied in many ways, including to:
• Generate electricity by heating trapped air which rotates turbines in a Solar updraft tower.
• Generate electricity in geosynchronous orbit using solar power satellites.
• Generate electricity using photovoltaic solar cells.
• Generate electricity using concentrated solar power.
• Generate hydrogen using photoelectrochemical cells.
• Heat and cool air through use of solar chimneys.
• Heat buildings, directly, through passive solar building design.
• Heat foodstuffs, through solar ovens.
• Heat water or air for domestic hot water and space heating needs using solar-thermal panels.
• Solar air conditioning
Biofuel
Plants use photosynthesis to grow and produce biomass. Also known as biomatter, biomass can be used directly as fuel or to produce liquid biofuel. Agriculturally produced biomass fuels, such as biodiesel, ethanol and bagasse (often a by-product of sugar cane cultivation) can be burned in internal combustion engines or boilers. Typically biofuel is burned to release its stored chemical energy. Research into more efficient methods of converting biofuels and other fuels into electricity utilizing fuel cells is an area of very active work.
Liquid biofuel
Information on pump, California.
Liquid biofuel is usually either a bioalcohol such as ethanol fuel or a bio-oil such as biodiesel and straight vegetable oil. Biodiesel can be used in modern diesel vehicles with little or no modification to the engine and can be made from waste and virgin vegetable and animal oil and fats (lipids). Virgin vegetable oils can be used in modified diesel engines. In fact the Diesel engine was originally designed to run on vegetable oil rather than fossil fuel. A major benefit of biodiesel is lower emissions. The use of biodiesel reduces emission of carbon monoxide and other hydrocarbons by 20 to 40%.
In some areas corn, cornstalks, sugarbeets, sugar cane, and switchgrasses are grown specifically to produce ethanol (also known as grain alcohol) a liquid which can be used in internal combustion engines and fuel cells. Ethanol is being phased into the current energy infrastructure. E85 is a fuel composed of 85% ethanol and 15% gasoline that is sold to consumers. Biobutanol is being developed as an alternative to bioethanol. There is growing international criticism about biofuels from food crops with respect to issues such as food security, environmental impacts (deforestation) and energy balance.
Solid biomass
Sugar cane residue can be used as a biofuel
Solid biomass is mostly commonly usually used directly as a combustible fuel, producing 10-20 MJ/kg of heat.
Its forms and sources include wood fuel, the biogenic portion of municipal solid waste, or the unused portion of field crops. Field crops may or may not be grown intentionally as an energy crop, and the remaining plant byproduct used as a fuel. Most types of biomass contain energy. Even cow manure still contains two-thirds of the original energy consumed by the cow. Energy harvesting via a bioreactor is a cost-effective solution to the waste disposal issues faced by the dairy farmer, and can produce enough biogas to run a farm.
With current technology, it is not ideally suited for use as a transportation fuel. Most transportation vehicles require power sources with high power density, such as that provided by internal combustion engines. These engines generally require clean burning fuels, which are generally in liquid form, and to a lesser extent, compressed gaseous phase. Liquids are more portable because they have high energy density, and they can be pumped, which makes handling easier. This is why most transportation fuels are liquids.
Non-transportation applications can usually tolerate the low power-density of external combustion engines, that can run directly on less-expensive solid biomass fuel, for combined heat and power. One type of biomass is wood, which has been used for millennia in varying quantities, and more recently is finding increased use. Two billion people currently cook every day, and heat their homes in the winter by burning biomass, which is a major contributor to man-made climate change global warming. The black soot that is being carried from Asia to polar ice caps is causing them to melt faster in the summer. In the 19th century, wood-fired steam engines were common, contributing significantly to industrial revolution unhealthy air pollution. Coal is a form of biomass that has been compressed over millennia to produce a non-renewable, highly-polluting fossil fuel.
Wood and its byproducts can now be converted through process such as gasification into biofuels such as woodgas, biogas, methanol or ethanol fuel; although further development may be required to make these methods affordable and practical. Sugar cane residue, wheat chaff, com cobs and other plant matter can be, and are, burned quite successfully. The net carbon dioxide emissions that are added to the atmosphere by this process are only from the fossil fuel that was consumed to plant, fertilize, harvest and transport the biomass.
Processes to harvest biomass from short-rotation poplars and willows, and perennial grasses such as switchgrass, phalaris, and miscanthus, require less frequent cultivation and less nitrogen than from typical annual crops. Pelletizing miscanthus and burning it to generate electricity is being studied and may be economically viable.
Biogas
Biogas can easily be produced from current waste streams, such as: paper production, sugar production, sewage, animal waste and so forth. These various waste streams have to be slurried together and allowed to naturally ferment, producing methane gas. This can be done by converting current sewage plants into biogas plants. When a biogas plant has extracted all the methane it can, the remains are sometimes better suitable as fertilizer than the original biomass.
Alternatively biogas can be produced via advanced waste processing systems such as mechanical biological treatment. These systems recover the recyclable elements of household waste and process the biodegradable fraction in anaerobic digesters.
Renewable natural gas is a biogas which has been upgraded to a quality similar to natural gas. By upgrading the quality to that of natural gas, it becomes possible to distribute the gas to the mass market via gas grid.
Geothermal energy
Krafla Geothermal Station in northeast Iceland
Geothermal energy is energy obtained by tapping the heat of the earth itself, usually from kilometers deep into the Earth’s crust. It is expensive to build a power station but operating costs are low resulting in low energy costs for suitable sites. Ultimately, this energy derives from heat in the Earth’s core. The government of Iceland states: “It should be stressed that the geothermal resource is not strictly renewable in the same sense as the hydro resource.” It estimates that Iceland’s geothermal energy could provide 1700 MW for over 100 years, compared to the current production of 140 MW. Radioactive elements in the earth’s crust continuously decay, replenishing the heat. The International Energy Agency classifies geothermal power as renewable.
Three types of power plants are used to generate power from geothermal energy: dry steam, flash, and binary. Dry steam plants take steam out of fractures in the ground and use it to directly drive a turbine that spins a generator. Flash plants take hot water, usually at temperatures over 200 °C, out of the ground, and allows it to boil as it rises to the surface then separates the steam phase in steam/water separators and then runs the steam through a turbine. In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine. The condensed steam and remaining geothermal fluid from all three types of plants are injected back into the hot rock to pick up more heat.
The geothermal energy from the core of the Earth is closer to the surface in some areas than in others. Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. Such geothermal power sources exist in certain geologically unstable parts of the world such as Chile, Iceland, New Zealand, United States, the Philippines and Italy. The two most prominent areas for this in the United States are in the Yellowstone basin and in northern California. Iceland produced 170 MW geothermal power and heated 86% of all houses in the year 2000 through geothermal energy. Some 8000 MW of capacity is operational in total.
There is also the potential to generate geothermal energy from hot dry rocks. Holes at least 3 km deep are drilled into the earth. Some of these holes pump water into the earth, while other holes pump hot water out. The heat resource consists of hot underground radiogenic granite rocks, which heat up when there is enough sediment between the rock and the earths surface. Several companies in Australia are exploring this technology.
Renewable energy commercialization
Costs
Source 2001 energy costs Potential future energy cost
Electricity
Wind 4–8 ¢/kWh 3–10 ¢/kWh
Solar photovoltaic 25–160 ¢/kWh 5–25 ¢/kWh
Solar thermal 12–34 ¢/kWh 4–20 ¢/kWh
Large hydropower 2–10 ¢/kWh 2–10 ¢/kWh
Small hydropower 2–12 ¢/kWh 2–10 ¢/kWh
Geothermal 2–10 ¢/kWh 1–8 ¢/kWh
Biomass 3–12 ¢/kWh 4–10 ¢/kWh
Coal (comparison) 4 ¢/kWh
Heat
Geothermal Heat 0.5–5 ¢/kWh 0.5–5 ¢/kWh
Biomass — heat 1–6 ¢/kWh 1–5 ¢/kWh
Low Temp Solar Heat 2–25 ¢/kWh 2–10 ¢/kWh
All costs are in 2001 US$-cent per kilowatt-hour.
New generation of solar thermal plants
The 11 megawatt PS10 solar power tower in Spain produces electricity from the sun using 624 large movable mirrors called heliostats.
Aerial view of one of the SEGS plants.
Since 2004 there has been renewed interest in solar thermal power stations and two plants were completed during 2006/2007: the 64 MW Nevada Solar One and the 11 MW PS10 solar power tower in Spain. Three 50 MW trough plants were under construction in Spain at the end of 2007 with 10 additional 50 MW plants planned. In the United States, utilities in California and Florida have announced plans (or contracted for) at least eight new projects totaling more than 2,000 MW.
In developing countries, three world bank projects for integrated CSP/combined-cycle gas-turbine power plants in Egypt, Mexico, and Morocco were approved during 2006/2007.
There are several solar thermal power plant in the Mojave Desert which supply power to the electricity grid. Solar Energy Generating Systems (SEGS) is the name given to nine solar power plants in the Mojave Desert which were built in the 1980s. These plants have a combined capacity of 354 MW making them the largest solar power installation in the world.
World’s largest photovoltaic power plants
Several large photovoltaic power plants have been completed in Spain in 2008: the Parque Fotovoltaico Olmedilla de Alarcon (60 MW), Parque Solar Merida/Don Alvaro (30 MW), Planta solar Fuente Alamo (26 MW), Planta fotovoltaica de Lucainena de las Torres (23.2 MW), Parque Fotovoltaico Abertura Solar (23.1 MW), Parque Solar Hoya de Los Vincentes (23 MW), the Solarpark Calveron (21 MW), and the Planta Solar La Magascona (20 MW).
First Solar 40 MW PV Array installed by JUWI Group in Waldpolenz, Germany
Waldpolenz Solar Park, which will be the world’s largest thin-flim photovoltaic (PV) power system, is being built at a former military air base to the east of Leipzig in Germany. The power plant will be a 40-megawatt solar power system using state-of-the-art thin film technology, and should be finished by the end of 2009. 550,000 First Solar thin-film modules will be used, which will supply 40,000 MWh of electricity per year.
Topaz Solar Farm is a proposed 550 MW solar photovoltaic power plant which is to be built northwest of California Valley in the USA at a cost of over $1 billion. Built on 9.5 square miles (25 km2) of ranchland, the project would utilize thin-film PV panels designed and manufactured by OptiSolar in Hayward and Sacramento. The project would deliver approximately 1,100 gigawatt-hours (GWh) annually of renewable energy. The project is expected to begin construction in 2010, begin power delivery in 2011, and be fully operational by 2013.
High Plains Ranch is a proposed 250 MW solar photovoltaic power plant which is to be built by Sun Power in the Carrizo Plain, northwest of California Valley.
However, when it comes to renewable energy systems and PV, it is not just large systems that matter. Building-Integrated Photovoltaics or “onsite” PV systems have the advantage of being matched to end use energy needs in terms of scale. So the energy is supplied close to where it is needed.
Environmental and social considerations
While most renewable energy sources do not produce pollution directly, the materials, industrial processes, and construction equipment used to create them may generate waste and pollution. Some renewable energy systems actually create environmental problems. For instance, older wind turbines can be hazardous to flying birds.
Land area required
Another environmental issue, particularly with biomass and biofuels, is the large amount of land required to harvest energy, which otherwise could be used for other purposes or left as undeveloped land. However, it should be pointed out that these fuels may reduce the need for harvesting non-renewable energy sources, such as vast strip-mined areas and slag mountains for coal, safety zones around nuclear plants, and hundreds of square miles being strip-mined for oil sands. These responses, however, do not account for the extremely high biodiversity and endemism of land used for ethanol crops, particularly sugar cane.
In the U.S., crops grown for biofuels are the most land- and water-intensive of the renewable energy sources. In 2005, about 12% of the nation’s corn crop (covering 11 million acres (45,000 km²) of farmland) was used to produce four billion gallons of ethanol—which equates to about 2% of annual U.S. gasoline consumption. For biofuels to make a much larger contribution to the energy economy, the industry will have to accelerate the development of new feedstocks, agricultural practices, and technologies that are more land and water efficient. Already, the efficiency of biofuels production has increased significantly and there are new methods to boost biofuel production.
Hydroelectric dams
The major advantage of hydroelectric systems is the elimination of the cost of fuel. Other advantages include longer life than fuel-fired generation, low operating costs, and the provision of facilities for water sports. Operation of pumped-storage plants improves the daily load factor of the generation system. Overall, hydroelectric power can be far less expensive than electricity generated from fossil fuels or nuclear energy, and areas with abundant hydroelectric power attract industry.
However, there are several major disadvantages of hydroelectric systems. These include: dislocation of people living where the reservoirs are planned, release of significant amounts of carbon dioxide at construction and flooding of the reservoir, disruption of aquatic ecosystems and birdlife, adverse impacts on the river environment, potential risks of sabotage and terrorism, and in rare cases catastrophic failure of the dam wall.
Hydroelectric power is now more difficult to site in developed nations because most major sites within these nations are either already being exploited or may be unavailable for other reasons such as environmental considerations.
Wind farms
Wind power is one of the most environmentally friendly sources of renewable energy
A wind farm, when installed on agricultural land, has one of the lowest environmental impacts of all energy sources:
• It occupies less land area per kilowatt-hour (kWh) of electricity generated than any other energy conversion system, apart from rooftop solar energy, and is compatible with grazing and crops.
• It generates the energy used in its construction in just 3 months of operation, yet its operational lifetime is 20–25 years.
• Greenhouse gas emissions and air pollution produced by its construction are tiny and declining. There are no emissions or pollution produced by its operation.
• In substituting for base-load coal power, wind power produces a net decrease in greenhouse gas emissions and air pollution, and a net increase in biodiversity.
• Modern wind turbines are almost silent and rotate so slowly (in terms of revolutions per minute) that they are rarely a hazard to birds.
Studies of birds and offshore wind farms in Europe have found that there are very few bird collisions. Several offshore wind sites in Europe have been in areas heavily used by seabirds. Improvements in wind turbine design, including a much slower rate of rotation of the blades and a smooth tower base instead of perchable lattice towers, have helped reduce bird mortality at wind farms around the world. However older smaller wind turbines may be hazardous to flying birds. Birds are severely impacted by fossil fuel energy; examples include birds dying from exposure to oil spills, habitat loss from acid rain and mountaintop removal coal mining, and mercury poisoning.
Other issues
Sustainability
Renewable energy sources are generally sustainable in the sense that they cannot “run out” as well as in the sense that their environmental and social impacts are generally more benign than those of fossil. However, both biomass and geothermal energy require wise management if they are to be used in a sustainable manner. For all of the other renewables, almost any realistic rate of use would be unlikely to approach their rate of replenishment by nature.
Transmission
If renewable and distribution generation were to become widespread, electric power transmission and electricity distribution systems might no longer be the main distributors of electrical energy but would operate to balance the electricity needs of local communities. Those with surplus energy would sell to areas needing “top ups”. That is, network operation would require a shift from ‘passive management’ — where generators are hooked up and the system is operated to get electricity ‘downstream’ to the consumer — to ‘active management’, wherein generators are spread across a network and inputs and outputs need to be constantly monitored to ensure proper balancing occurs within the system. Some governments and regulators are moving to address this, though much remains to be done. One potential solution is the increased use of active management of electricity transmission and distribution networks. This will require significant changes in the way that such networks are operated.
However, on a smaller scale, use of renewable energy produced on site reduces burdens on electricity distribution systems. Current systems, while rarely economically efficient, have shown that an average household with an appropriately-sized solar panel array and energy storage system needs electricity from outside sources for only a few hours per week. By matching electricity supply to end-use needs, advocates of renewable energy and the soft energy path believe electricity systems will become smaller and easier to manage, rather than the opposite.
Controversy over nuclear power as a renewable energy source
In 1983, physicist Bernard Cohen proposed that uranium is effectively inexhaustible, and could therefore be considered a renewable source of energy. He claims that fast breeder reactors, fueled by uranium extracted from seawater, could supply energy at least as long as the sun’s expected remaining lifespan of five billion years. Nuclear energy has also been referred to as “renewable” by the politicians George W. Bush, Charlie Crist, and David Sainsbury.
Inclusion under the “renewable energy” classification could render nuclear power projects eligible for development aid under various jurisdictions. However, it has not been established that nuclear energy is inexhaustible, and issues such as peak uranium and uranium depletion are ongoing debates. No legislative body has yet included nuclear energy under any legal definition of “renewable energy sources” for provision of development support. Similarly, statutory and scientific definitions of renewable energies usually exclude nuclear energy. Commonly sourced definitions of renewable energy sources often omit or explicitly exclude nuclear energy sources as examples.Nuclear fission is not regarded as renewable by the U.S. DOE on the website “What is Energy?”
There are also environmental concerns over nuclear power, including the dangerous environmental hazards of nuclear waste and concerns that development of new plants cannot happen quickly enough to reduce CO2 emissions, such that nuclear energy is neither efficient nor effective in cutting CO2 emissions.
ADVANTAGES AND DISADVANTAGES OF RENEWABLE ENERGY:
There are many energy sources today that are extremely limited in supply. Some of these sources include oil, natural gas, and coal. It is a matter of time before they will be exhausted.
Estimates are that they can only meet our energy demands for another fifty to seventy years. So in an effort to find alternative forms of energy, the world has turned to renewable energy sources as the solution. There are many advantages and disadvantages to this.
Renewable energy sources consist of solar, hydro, wind, geothermal, ocean and biomass. The most common advantage of each is that they are renewable and cannot be depleted. They are a clean energy, as they don’t pollute the air, and they don’t contribute to global warming or greenhouse effects. Since their sources are natural the cost of operations is reduced and they also require less maintenance on their plants. A common disadvantage to all is that it is difficult to produce the large quantities of electricity their counterpart the fossil fuels are able to. Since they are also new technologies, the cost of initiating them is high.
Solar energy makes use of the sun’s energy. It is advantageous because the systems can fit into existing buildings and it does not affect land use. But since the area of the collectors is large, more materials are required. Solar radiation is also controlled by geography. And it is limited to daytime hours and non-cloudy days.
Wind energy uses the power of the wind to produce electricity. Although it is the largest job producer, it is reliant on strong winds. Wind turbines are large and, although you can use the area under them for farming, many consider them unattractive looking. They are also very noisy to operate. In addition, they threaten the wild bird population.
Hydroelectric energy uses water to produce power. This is the most reliable of all the renewable energy sources. On the down side, it affects ecology and causes downstream problems. The decay of vegetation along the riverbed can cause the buildup of methane. Methane is a contributing gas to greenhouse effect. Dams can also alter the natural river flow and affect wildlife. Colder, oxygen poor water can be released into the river, killing fish. And the release of water from the dam can cause flooding.
Geothermal energy uses steam from the Earth’s ground to generate power. It uses smaller land areas than other power plants. They can run 24 hours per day, every day of the year. Disadvantages are that it is very site specific and, along with the heat from the Earth, it can also bring up toxic chemicals when obtaining the steam. Drilling geothermal reservoirs and finding them can be an expensive task.
Biomass electricity is produced through the energies from wood, agricultural and municipal waste. It helps save on landfill waste but transportation can be expensive and ecological diversity of land may be affected. In addition, its process needs to be made simpler.
Ocean energy is a clean and abundant energy form. It does, however, have high costs. Ocean thermal energy also requires close to a forty degree Fahrenheit difference in water temperature year round. In addition, construction and laying pipes can cause damage to the ecosystem.
There are many advantages to the use of renewable energy sources. There are also some disadvantages. The fact is energy demands will continue to increase. Through research and development, as well as, new technologies, the hope is many of the disadvantages of renewable sources of energy can be eliminated and we can successfully incorporate it into our power supplies.
N.Sankari
http://www.articlesbase.com/electronics-articles/renewable-energy-707358.html
The key to buying sunglasses in today’s world should consist of two major considerations: health issues and fashion. Purchasing new sunglasses for reasons that don’t pacify both of those issues is like throwing money out of the window, since you will not use those sunglasses as much as you should, or would if they met both criteria. Trust me on this. In today’s world, even celebrities, newscasters, and sportscasters choose sunglasses based on both of these criteria.
From a health perspective, you need to get sunglasses that are healthy. That means that the tint and the polarized glass must not trade the distortion of color and decreased contrast for less visual clarity. To be useful as well as functional, good sunglasses need to shield your eyes from the brightness via shading or reduced contrast, but must not overly reduce visual clarity in the process, this is not an equal tradeoff.
From another health perspective, it has been known for many years that consistent exposure to the sun’s UV rays can be harmful. Your sunglasses should protect you from those UV rays via the polarized lenses, as well as a more recently discovered danger known as HEVL or High Energy Visible Light.
Both of these issues are particularly important for people who depend on visual clarity to do what they must do or need to do, perhaps as part of their job or as a part of a recreational activity. Think about the airline pilot whose eyes may be in sunlight for the entire duration of a flight. Think about the truck driver who may be driving west late in the day, and looking into the sun for the majority of his travels. Think about the recreational skier or snow-boarder who is addition to the normal hazards of sunlight is also faced with the additional hazard of “snow blindness” where the bright sunlight is reflected off the white snow that he is surrounded by. All of these types of people know how important it is to adequately protect your eyes, and this importance is not decreased even if you do not spend as much time in sunlight as they do.
Studies have also shown that when you are using your eyes constantly as part of a concentrated effort to what you are doing, such as when driving in heavy traffic or skiing, it takes a tremendous amount of energy from your body to keep processing the massive amounts of information that your eyes are sending to your brain. For this reason also, good sunglasses will allow your eyes to do their job better without using more energy that you need to.
From a fashion standpoint, choosing sunglasses that are “good for you” does not mean that the sunglasses need to look like the glasses equivalent of orthopedic shoes, not at all. Sunglasses that meet the protection and health criteria above are readily available from the major fashion sunglasses and designer sunglasses manufacturers, including designers such as Oakley, Serengetti, RayBan, Maui Jim, Wiley, Bolle and more. In fact, some of the higher-end choices you have in these designer sunglasses also have additional features such as built-in Bluetooth so that you can use your MP3 player or your cell phone without taking off your sunglasses.
Finally, make sure the sunglasses are comfortable. With all the choices you have available to you, comfort needs to be a major part of the equation, and it not an area where you need to scrimp or sacrifice.
Jon Arnold
http://www.articlesbase.com/health-articles/choosing-designer-sunglasses-that-still-protect-you-87865.html
You feel like you’re a square peg in a round hole at the office. You see yourself as a fashion icon or someone who knows the latest trends in clothing, make up and accessories and who dresses and acts in like manner. You have used your knowledge to help out your fashion-challenged friends and family members, turning them from dowdy ducks into graceful swans through the right clothes, the correct make-up and a few lessons in proper bearing, walk and projection.
However, you’re working in an office where the majority dress as if they were stuck in the fifties.
You decide it’s time to look for more suitable employment, perhaps in a company where the dress code is much more suited to your style. You can also be more adventurous by eschewing your boring office job for a career in image consulting.
The Up-and-Coming World of Image Consulting
There is a multitude of fashion- and image-challenged people and companies out there. “Power suits” may be in vogue, but most people do not even know what it means. Watching shows like Extreme Makeover, Project Runway or Queer Eye for the Straight Guy does not automatically make one a good dresser.
This is the reason why image consulting is fast becoming a major business in the country today. Image, in today’s visually-conscious environment, is everything. Those who are out of step quickly find themselves left behind and unsure of how to catch up.
At the same time, people (and companies) realize that image isn’t a matter of fashion or physical appearance alone. People form impressions on how someone looks and behaves – vocal communications (how a person speaks, his grammar, vocabulary, diction), non-verbal cues (handshakes, posture, eye contact), and etiquette – from how a person dines to how he handles a cell phone during meetings.
There are a lot of people who need help in crafting an image: women who want a new look, job-seekers who want to create a favorable first impression, corporate executives and their spouses, lawyers and their clients, cancer survivors, singles seeking a partner, and so on.
The field is wide open, and if you have the skills and abilities, you may just be in a position to establish your own image consulting business.
Skills, Abilities and First Steps
If you’re someone with a strong visual sense and excellent communications skills plus a large dose of diplomacy and tact in your genetic make-up, you have the basic tools that you need.
Diplomacy and tact are a definite requirement. Bear in mind that you are only ‘advising’ someone on what to wear, say or do. Most people resist change; you must be able to guide your clients onto the proper path without antagonizing them.
Fashion sense is of course important. You need to be able to advise your clients on what to wear, what not to wear, what make-up and accessories go with what for a wide range of occasions: corporate meetings, casual Fridays, dinner with the boss, conventions and the like.
Start small and gain experience as you go. Offer free makeovers to friends, family members and office mates. Learn how to deal with people and, at the same time, start making contacts – hair stylists, makeup artists, nutritionists and personal trainers, voice coaches and the like. Not only can they advise you on the current trends; you can refer clients to them for things that you are not capable of handling. They can reciprocate the favor by referring people to you.
Bear in mind the need to establish your reputation and abilities. Take ‘before’ and ‘after’ shots of your initial clients (friends, family members, office mates) so you’ll have an image consulting portfolio to show off to prospective clients who may soon become your paying clients.
Most importantly, bear in mind that your first client is yourself. You cannot become a credible image consultant unless you project that image yourself. Start with yourself, gain experience through friends and family, get your name and reputation out there and soon enough, you’ll be run off your feet dealing with paying clients.
Steven French
http://www.articlesbase.com/careers-articles/getting-into-the-business-of-image-consulting-119477.html
Cell phones give off radiation. Here’s a demonstration with a meter so you can actually see the EMFs. Here we demonstrate a solution to prevent radiation from getting to you brain. A patented hollow-tube airtube, sound tube headset that works!
Duration : 0:3:46
When you want to text or picture message with other phones, you can use your Sidekick or hiptop Danger-powered device. Here’s how.
Duration : 0:1:46
Scientists speak out on mobile phone, cancer link
http://www.bevolution.org – free download of brainwave model
Mobile Phones Radiation – what are the real health risks and facts? Is it safe or not? That is the question.
Professor Olle Johansson of the Karolinska Institute in Sweden has researched for 30 years in the electromagnetic radiation field (EMR/EMF).
Download the videolist and his CV in pdf at www.bevolution.dk
This interview in 15 parts can change your life when you really pay attention and are aware – your world view will probably transform during the 15 video parts.
This is an interview with the world known scientist assoc. professor Olle Johansson from the famous Karolinska Institute in Stockholm in Sweden and
professor at The Royal Institute of Technology in Stockholm too.
The question being discussed is about mobile Phone Radiation: Is it safe or is it not?
Independent researcher in consciousness (energy, frequency and vibration) Morten Julius from Denmark is interviewing the honourable Olle Johansson.
The Human Project has produced this interview and you can download documents and get to know more at
www.bevolution.dk
Thank you for sharing with all you know and wish the best.
Stay tuned and enjoy!
Duration : 0:9:59
http://www.emfnews.org
cell phone radiation is becoming a popular topic among many when it comes to health. Many once believed that the idea of radiation being emitted from these products was just an urban myth. However, after many years of scientific research, it has been established that these telecommunication devices do, in fact, emit some level of danger – with electromagnetic radiation. This happens because in order for a user of these devices to receive a signal to make a receive calls, radio signals must be present. These are transmitted using radio-frequency energy. This form of energy is a type of radiation that is considered to be “electromagnetic”. Here, you will learn about cell Phone Radiation and how you can avoid the risk with the Blue Tube Headset.
www.emfnews.org/qlinks.html
When I first learned of the complications that cell phones could potentially pose to individuals, I started conducting research on ways that I could protect myself, as well as my friends and loved ones from this danger without completely eliminating these convenient devices from our lives altogether. It is then I discovered what is referred to as the “airtube headset”. While this was considered to be an effective remedy for many years, eventually I ran across a new product that was referred to as the “Blue Tube Headset”. This device was more structurally sound and seemed to provide a higher shield level from exposure to dangerous energy levels emitted from cell phones. The team that designed this piece actually worked for over a decade to ensure:
1. The product was durable and could be used for an extended amount of time without experiencing damage.
2. It was created with the concept of the airtube headset in mind, but it actually filtered transmissions away from the head and the ear canal.
3. In addition to this, the quality of sound was very clear.
www.emfnews.org/headset.html
Duration : 0:0:37
Testosterone hormone is produced by testicles in men. It is responsible for development of male sexual characters like physical strength, muscle mass, body shape, body hair, deep voice, sexual function etc. Erectile dysfunction occurs when testosterone level is reduced. But this is not the only cause for erectile dysfunction.
Causes for low testosterone levels:
Age: The testosterone level in blood start reducing as age advances .Usually it starts between 35 to 45 years of age. Irrespective of age the andropause in men sets in as the testosterone level starts dipping.
Injury to testicles: Testicles are prone to injury as they are suspended outside the abdomen. Injury to both testicles can reduce testosterone production
Infection of testicles: If mumps infection during adolescence or early adult hood involves testicles it may affect testosterone production
Cancer treatments: The treatments for cancers like chemotherapy or radiation therapy may temporarily cause reduction of testosterone levels. But some times it may become permanent.
Diseases : Chronic kidney related diseases, Cirrhosis of liver, Sarcoidosis, chronic illness etc can also cause low testosterone levels .
Medications: Corticosteroid medications and medicines used to treat prostate cancer can cause lowered testosterone level.
Apart from the above mentioned reasons alcoholism, stress, insufficient exercise, obesity and a poor diet which is not rich in nutrients can also cause lowered testosterone levels.
Symptoms of lowered testosterone levels
• Erectile dysfunction
• Obesity
• Osteoporosis
• Infertility
• Low sexual drive
• Fatigue or weakness
• Enlarged male breasts
• Decreased body hair
• Loss of muscle mass
• Depression
• Loss of concentration.
• Mild anemia
Simple natural ways to increase testosterone level
• Increased weight or obesity leads to increased estrogen levels. Increased estrogen lowers testosterone level. Hence try to shed excess fat. Do not fast or skip meals to shred excess fat. Once again poor eating habit reduces testosterone level. Losing 2kgs of weight per month is always ideal.
• Do not take a diet which is very high in protein. Reduce carbohydrates, sugar and oil content in daily diet.
• Regular eating habit prevents frequent fluctuation of hormonal level.
• Exercise regularly.
• Perform sex frequently specially in morning. Frequent sex reduces weight and increases testosterone levels.
• Eat pea nuts, pea nut butter and olive oil.
• Reduce alcohol intake
• Relax and try to distress. Yoga and meditation help to reduce stress level.
Dr Savitha Suri
http://www.articlesbase.com/alternative-medicine-articles/natural-ways-to-increase-testosterone-270325.html
There continues to be a great deal of activity surrounding the update to NFPA 70E scheduled to be published in October 2008. For the proposed 2008 edition of NFPA 70, National Electrical Code® (NEC®), the Technical Correlating Committee (TCC) received 3,668 proposals and 3,206 comments during the revision cycle. For those of us involved in working with energized electrical circuits the outcome of the new standards will likely impact how we do our job. The goal is to increase safety through well thought through practices.
How are Thermographers Addressing the Issue?
Increasing the distance at which inspections of open cabinets are performed.
Most cameras offer telephoto lens that enable the thermographer to stand 2 to 3 times further away from the energized components while maintaining the same resolution. In addition newer high definition cameras will provide the same performance as 320×240 array based cameras at twice the normal standoff.
New Language Being Drafted by NFPA and ASTM
ASTM E-1934
New language is being proposed in the next version of ASTM E-1934, Standard of Examining Electrical Power Distribution Equipment with Infrared Technology. 7.5 – As an alternative, consideration may be given to conducting the examination through “windows” that are transparent to detected infrared radiation or to “ports.” Safety procedures should be modified to accommodate this task. Care must be taken to insure that all equipment can be seen and special lenses may be required.
Did You Know?
Incident energy from an arc flash created with vertical, unterminated conductors in a cabinet (20″ x 20″ x 20″) decreases by the inverse of the distance to the 1.5 power. If the arc has horizontal conductors that point out of the cabinet opening or vertical which terminate into an insulated barrier, the exposure may decrease by a lower exponent, but not enough data has been collected on these conductor configurations. - Tom Neal of Neal Associates
Next Revision of NFPA 70E
The following new language has been submitted to, and is being considered, by the 70E committee: “When access to conduct such inspections of energized equipment is limited by the appropriate use of special windows or small access ports, rather than by gaining access though opening the enclosure door, the limit of the approach, and the required PPE, will be the same as if the enclosure door were left unopened.”
Increased diligence of OSHA
Although it is only referenced in OSHA 29 CFR Part 1910 Subpart S, Appendix A, NFPA 70E is considered by OSHA to be the recognized industry practice for electrical safety.
Role of NFPA
OSHA standards don’t provide details on how to conduct an electrical hazard assessment or how to select PPE. For guidance on compliance, you need to look to national consensus standards. NFPA is one of the foremost consensus standards for electrical safety. It covers employee protection from the electrical hazards of shock, arc flash and arc blasts.
NFPA Compliance Part I – Installation Safety Requirements
Covers safety requirements for the design and installation of electric conductors and equipment. Essential to the proper use of Part I of this standard is the understanding that it is not intended to be applied as a design, installation, modification, or construction standard for an electrical installation or system. Its content has been intentionally limited in comparison to the content of the NEC in order to apply to an electrical installation or system as part of an employee’s workplace. This standard is compatible with corresponding provisions of the NEC, but is not intended to, nor can it, be used in lieu of the NEC.
Part 2 – Safety Related Work Practices
Covers electrical safety related work practices and procedures for employees who work on or near exposed energized electrical conductors or circuit parts. Electrical hazard includes arc flash. Relevant requirements include:
- Power must be proven to be off before performing work.
This includes:
- The safe interruption of the load and opening of the disconnect
- Visual verification/voltage testing to ensure deenergization
- The potential electrical hazard must be identified and documented
- Flash hazard analysis must be performed
- Flash protection boundaries must be determined
- Appropriate steps must be taken to protect persons working near live parts or within the flash protection boundary
- Personal Protective Equipment must be provided, based on the relevant incident energy exposure levels (cal/cm2)
- Only properly qualified persons shall be allowed to perform work
Part 3 – Safety Related Maintenance Requirements
Covers practical safety-related maintenance requirements for electrical equipment and installations in workplaces.
Part 4 – Safety Requirements for Special Equipment
Covers electrical safety installation requirements and safety-related work practices and procedures for employees who work on or near special electrical equipment such as electrolytic cells.
Preventing Arc Flash Incidents
Step 1. Perform Hazard Assessment and Create Warning Labels
The label is the first step. However, determining the arc-flash levels may change as routine maintenance and repair is performed. The level of arc-flash hazard of any piece of equipment depends on the level of arc-fault current and the time it takes to trip the nearest upstream over current protection device. In most cases, a local utility engineer can determine the fault current levels; however these fault current values may be based on the impedance of the transformer that serves the facility, and additional impedances upstream of the transformer can lower the number. If these additional impedances are not included in the calculations, then the incident energy levels may be under-estimated. Short-circuit current levels in electric utility systems are continuously changing as both electricians and maintenance workers replace over current devices, fuses and panel boards or upgrades are made to the system. Any of theses changes can have an effect on the arc-flash energy level, but may not be noted on the warning label.
Step 2. Provide Protective Clothing
The next step is to ensure that anyone working on equipment that might generate arc flash wear protective clothing, including fire retardant suits, gloves, face shield/goggles and other gear as provided by the standards.
Step 3. Equipment That Limits Exposure
Although no single piece of equipment can completely eliminate arc flash hazards, making it convenient to perform most routine maintenance tasks without directly accessing the equipment can significantly reduce the risk. Providing external plug-ins to equipment inside an enclosure is one approach. Properly designed and insulated panels that are wired to the appropriate equipment inside allows operators to change settings and monitor performance without opening the enclosure. With a traditional disconnect switch inside the main enclosure, live power is still present on the line side of the disconnect switch. Since live power is still being fed upstream to the disconnect switch on the panel, the threat of an arc flash incident remains. Another approach is to develop arc-resistant electrical cabinets designed to contain the arc energy and direct it away from personnel- – they cannot prevent an arc flash. “Arc-resistant” describes equipment designed to control arc flash exposure by extinguishing the arc, by controlling the spread of the arc or by channeling the arc pressure wave away from personnel. Arc-resistant designs represent enhanced safety technology and, therefore, an enhanced level of safety.” The design redirects arc flash energy out relief vents at the top of the unit and away from personnel through an overhead plenum. These products have been successfully tested in accordance with ANSI C37.20.7: IEEE Guide for Testing Medium-Voltage Metal- Enclosed Switchgear for Internal Arcing Faults. During testing, cotton squares (similar to 4.5 oz/yard untreated T-shirt material) are mounted a meter from the MCC. Acceptance criteria require that none of the cotton indicators ignite during or following a test. To redirect the arc exhaust gases, specialized silicone coated, aluminum pressure relief vents on the unit’s roof open to release the pressure. A plenum system above the enclosure channels the superheated gas and vaporized copper and steel to a safe and controlled location.
Standards Organizations and Arc Flash Protection
To protect operators, OSHA and NFPA 70E standards require a “flash protection boundary.” OSHA has adopted the National Fire Protection Association’s “70E Standards for Electric Safety in the Workplace” as an acceptable means of compliance to meet this requirement. Section 1910.333 of Subpart S states: “Safety-related work practices shall be employed to prevent electrical shock or other injuries resulting from either direct or indirect electrical contacts”. Therefore companies should take great lengths to ensure that electrical workers are safe from arc-flash dangers.
References:
Organizations Involved In This Work
NFPA – The National Fire Protection Agency
The mission of the international nonprofit NFPA is to reduce the worldwide burden of fire and other hazards on the quality of life by providing and advocating consensus codes and standards, research, training, and education. NFPA membership totals more than 81,000 individuals from around the world and more than 80 national trade and professional organizations. Established in 1896, NFPA serves as the world’s leading advocate of fire prevention and is an authoritative source on public safety. In fact, NFPA’s 300 codes and standards influence every building, process, service, design, and installation in the United States, as well as many of those used in other countries. NFPA’s focus on true consensus has helped the association’s code-development process earn accreditation from the American National Standards Institute (ANSI).
OSHA – Occupational Safety & Health Administration
OSHA’s mission is to send every worker home whole and healthy every day. Since the agency was established in 1971, workplace fatalities have been cut by 62 percent and occupational injury and illness rates have declined 40 percent. At the same time, U.S. employment has nearly doubled from 56 million workers at 3.5 million worksites to 115 million workers at nearly 7 million sites.
ASTM
ASTM International (Originally known as the American Society for Testing and Materials) is one of the largest voluntary standards development organizations in the world-a trusted source for technical standards for materials, products, systems, and services. Known for their high technical quality and market relevancy, ASTM International standards have an important role in the information infrastructure that guides design, manufacturing and trade in the global economy.
IEEE – IEEE Electrical Safety
A predominant area of standards activity within the IEEE-SA addresses technology and related safety needs for the power and energy industry and subsequent industry applications. A key component to electrical safety is for those working with electrical current and within environments using electrical current to be abreast of standards and regulations that include safety best practices. It is critical for employees to familiarize themselves with these documents and the organizations responsible for developing them. The IEEE, namely via its Color Books Standards for Industrial and Commercial Power Systems and the National Electrical Safety Code, as well as its Power Engineering standards, is a major developer of standards that directly or indirectly address electrical safety within specific applications or environments.
Additional Resource Links
NFPA 70B Recommended Practice for Electrical Equipment Maintenance, 2006 Edition NFPA Journal May/June 2007 Newsletter
Please visit us at www.electrophysics.com/wpnfpaupab
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Electrophysics – IR Cameras for Thermography Professionals
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Josh White
http://www.articlesbase.com/electronics-articles/nfpa-70e-and-its-impact-on-thermographers-686788.html