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Renewable Energy

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 0.35x24x365 = 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.

                                                 

About the Author

What volume of water should be added to 600.mL of ethanol?

In order to have a solution that at 95.0 degrees Celsius
[For ethanol Kb=1.22 degrees Celsius/m,density=0.789 g.cm^3, boiling point=78.4 degrees Celsius]

Any help is appreciated I would really appreciate an explanation

_____bp and molality

dT = (95.0 - 78.4) C = (1.22 C/molal) * ?? molal

Solve for ?? molal = mole solute/kg solvent

ml water = (18 g /mole) * (1 ml/g) * (?? mole / kg solvent) * (0.600 liter * 0.789 kg/liter) = ??

Plug and SOLVE (around 140 ml)

Basic mathematics is a prerequisite to chemistry – I just try to help you with the methodology of solving the problem.

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BOILING POINT 120 CAPS $59.99 A Powerful And Advanced Fat Loss Accelerator! Description: Developed by a world-renowned team of exercise scientists and sports nutritionists, Boiling Point is a powerful and advanced fat loss formula! Recognizing that everyone is different and that many different factors are involved in weight loss, our scientific experts formulated Boiling Point to promote fat loss in no fewer than four different ways: by enhancing the breakdown of existing body fat by preventing the formation of new body fat by controlling appetite and by stimulating massive increases in metabolic rate (calorie burning) for hours on end. Never in the history of the supplement industry has so much technology been crammed into a two-capsule dose!We believe the secret of a successful formula is keeping things simple. Compare the synephrine, yohimbine, and caffeine contents of Boiling Point to the current best-selling fat loss formulas on the market. You?ll find that Boiling Point has higher quantities of each of these primary active ingredients (i.e., the horsepower behind the formula) than anyone else. The inclusion of LipoLean�, a proprietary thermogenic powerhouse that combines raspberry extract (Razberi-K� ), green tea extract (Catethin), and tyramine, takes Boiling Point to an entirely new level of effectiveness. Finally, to make sure all of these ingredients are fully absorbed and utilized by the body, Boiling Point has added a huge dose of Bioperine�, a patented extract of black pepper which has been scientifically proven to enhance the bioavailability of numerous vitamins, minerals, amino acids and antioxidants. Make no mistake, this is a cadre of powerful ingredients, all of which are included at mind-blowing dosages that easily eclipse all competitors on the market! Supplement Facts: Serving Size2Capsules Servings Per Container60 Amount Per Serving % Daily Value LipoLean� Proprietary Blend 400mg * Catethin� Green Tea Extract (60% EGCG), Razberi-K�(99% Raspberry Ketone), Tyramine Caffeine Anhydrous 300mg * Synephrine HCL 25mg * Black Pepper Extract 10mg * Yohimbine HCL 5mg * * Daily Value not established Ingredients: Gelatin, Silicon Dioxide, Vegetable Magnesium Stearate Directions: As a dietary supplement, take 1-2 capsules of Boiling Point� with 8 oz. of water before breakfast or morning workout, andanother 1-2 capsules 6-8 hours later. Do not exceed 4 capsules in any 24-hour period. Do not take within 6 hours of bedtime. If you haven't used this supplement previously, begin by takin 1 capsule twice per day for 5 days to assess your individual tolerance. For best results, use Boiling Point� for at least 30 days in conjunction with a healthy, calorie-reduced diet and regular exercise program. Improper use of this product will not improve results and is not advised. Individual results may vary.Warnings: Keep out of the reach of children. Not intended for persons under the age of 18, women who are pregnant or nursing, or the elderly. Do not use this produc

Boiling Point(1992) (DVD) $5.93 A U.S. Treasury (Wesley Snipes – DEMOLITION MAN, BLADE) agent is on the trail of a group of murdererous counterfeiters headed by Dennis Hopper (SPEED, APOCALYPSE NOW). He must bring them to justice and gain revenge for the slaying of his partner. Cast List: Dennis Hopper , Wesley Snipes , Viggo Mortensen , Dan Hedaya , Lolita Davidovich Produced: 1992 Running Time: 89 min Dennis Hopper (Texas Chainsaw Massacre 2, Blue Velvet, Apocalypse. Now)is Rudolph Red Diamond, a convicted criminal, a scam artist who always has a trick up his sleeve, who always looking for that one last, big job. Viggo Mortensen (The Lord Of The Rings Trilogy, A History Of Violence, Corlito's Way) is Ronnie, his sidekick, a low down, psychotic hoodlum searching for an easy buck. Things are tough on the streets for Rudolph and Ronnie and these small time crooks are about to get some big time trouble when a counterfeiting scam goes horribly wrong and thick, hot headed Ronnie ends up shooting and killing an undercover cop. Wesley Snipes (Blade Trilogy, Money Train, White Men Can't Jump) is Jimmy Mercer, a cop on the edge, a cop who has seven days before he's transferred and seven days to wreak revenge on the scum that killed his partner. Things are heating up and they're about to reach boiling point.

Brandon Wright - Boiling Point [Digipak] $12.81 Disc 1:Free ManDriftOdd Man OutBoiling PointHere`s That Rainy DayCastawayInterstate Love SongYou`re My Everything

Boiling Point - Road to Hell $9.9 Presente nel Pacchetto Essential : scarica più di 60 giochi a 9,90€ al mese - La strada per l'inferno. Tu sei Saul Mayers, un ex legionario e ha proprio un bel caratteraccio! Ti stavi tranquillamente godendo la vita da pensionato a Parigi, quando un giorno vieni informato che tua figlia, una giornalista, è stata rapita nella giungla colombiana. E' ora di riprendere servizio e andare a liberarla! Arrivato in Sud America, avrai 625 km quadrati da esplorare senza mai caricare nuove mappe, in totale libertà. La foresta è lussureggiante ma anche piena di pericoli. Potrai anche interagire con la popolazione locale per proseguire e ottenere informazioni utili. Ma considera sempre con attenzione ogni mossa e valuta le possibili conseguenze.

Boiling Point (Unabridged) $18.99 A long-dormant volcano in Chile fuses the destinies of two microbiologists, a celebrity scientist, and a Nobel Prize-winner....

Boiling Point - Import $14.44 Description not provided.

Boiling Point #3 $4.99 The girls' cooking service is up and running! The only problem is that business is too good! They have more customers than they can handle. Will their dreams of a successful business go up in smoke?

Degrassi: Boiling Point Soundtrack $13.85 Disc 1:BallsBelieve - MoneenOne of Those Pregnant TeenagersMr. Perfect - Jessica TylerConcert of the CenturyDon`t Say Love [Ralph Sall Edit] - All Too MuchStranger To Me - Hannah GeorgasI`m a Young AdultGood Times, The - RoyalchordGirlfriend Label, TheHand To Hold - AdalineThat is Pandemic!Whitehorse - Jessica Tyler/Raymond AblackScream At the Top of Your LungsCarjack My Heart - Dance MovieJust a Girl - Jessica TylerLast Night Was Epic!Paisley Jacket - The Dead HandSammy Decter - Eve And The OceanBig Changes

Boiling Point (Paperback) $7.91 As a Nobel Prize-winning scientist prepares to launch his diabolical plan by causing 56 volcanoes around the world to erupt, a celebrity scientist and two microbiologists must race against time to save humanity from an uncertain future. Original.

Boiling Point Understanding Men And Anger $13.99 "Being a man in the twenty-first century isn't easy. In fact, trying to live up to a masculine ideal that may be nothing more than myth has left many men frustrated and angry. Often unable to express their emotions, these men appear buttoned-up until a seemingly minor setback unleashes a torrent of rage that can destroy personal and professional relationships.Does this sound familiar?The mistakes of other drivers fill him with road rage Setbacks at work send him into a tailspin Unmet expectations in his relationship leave him seething Holidays and other occasions are filled with tension instead of joySuppressed anger, when it finally boils over, scalds everyone involved-including loved ones, co-workers, and even strangers.Christian counselors David Stoop and Stephen Arterburn offer solutions in this trade paper version of The Angry Man. They show what happens when men's deep-rooted anger starts to ruin relationships, jobs, and health, and they help sufferers find their way back from the brink. Men will find the help they need to reimagine a positive image of their masculinity; their loved ones will find advice on reaching a man at his boiling point."

Agilent Qualitative Boiling Point Calibration Sample 320 $168 The Agilent Qualitative Boiling Point Calibration Sample 320 Contains: Mixture of the following components, approximate concentrations % weight/weight: 6.9% n-pentane, 4.8% 2-methyl pentane, 3.6% n-hexane, 3.7% 2,4-dimethyl pentane, 3.

Degrassi: Boiling Point / Tv O.s.t. $14.99 Verve:001531302

Boiling Point : People in a Changing Climate $45.44 No Synopsis Available

Boiling Point Weight Loss 120 Caps $59.99 Boiling Point Weight LossImage yourself lean, shapely, and toned. Imagine having the type of figure you have always wanted chiseled, ripped abs -shredded vascular physique. Now imagine a supplement that can help you achieve all this and more. Nearly every diet supplement claims they will do this for you. They claim to be the most advanced, most powerful, and fat loss miracle we have been looking for and some for the ultimate weight loss solution. It helps control appetite allowing you lose your overall calorie intake throughout the day .

The Freezing-Point, Boiling-Point, And Conductivity Methods $25.79 No Synopsis Available

Boiling Point 120ct by Star Chem Labs Quick Fat Burner $59.99 Boiling Point Fat Burner! Boiling Point Amazing Fat Burner by Star Chem Labs here at Supplementstogo.com. What is Boiling Point by Star Chem Labs? Developed by a world-renowned team of exercise scientists and sports nutritionists, Boiling Point is the most powerful and most advanced fat loss formula on the market! Recognizing that everyone is different and that many different factors are involved in weight loss, our scientific experts formulated Boiling Point to promote rapid, dramatic fat loss in no fewer than four different ways: by enhancing the breakdown of existing body fat by preventing the formation of new body fat by controlling appetite and by stimulating massive increases in metabolic rate (calorie burning) for hours on end. Never in the history of the supplement industry has so much technology been crammed into a two-capsule dose! What makes Boiling Point better than other weight loss products We believe the secret of a successful formula is keeping things simple. Compare the synephrine, yohimbine, and caffeine contents of Boiling Point to the current best-selling fat loss formulas on the market. You’ll find that Boiling Point has higher quantities of each of these primary active ingredients (i.e., the horsepower behind the formula) than anyone else. The inclusion of LipoLean, a proprietary thermogenic powerhouse that combines raspberry extract (Razberi-K ), green tea extract (Catethin), and tyramine, takes Boiling Point to an entirely new level of effectiveness. Finally, to make sure all of these ingredients are fully absorbed and utilized by the body, Boiling Point has added a huge dose of Bioperine, a patented extract of black pepper which has been scientifically proven to enhance the bioavailability of numerous vitamins, minerals, amino acids and antioxidants. Make no mistake, this cadre of powerful ingredients, all of which are included at mind-blowing dosages that easily eclipse all competitors on the market, means that stubborn love handles, nasty lower back fat, and flabby thighs are an absolute thing of the past! Do I need to worry about side effects? There are no known side effects from using Boiling point (except rapid, dramatic fat loss). That said, remember that everyone responds differently to certain diets and training programs, it is important to thorougtly read the label warnings. Also, it is always a good idea to check with a knowledgeable physician before using any dietary supplement.

Skechers Women's Keepsakes-Boiling Point Mid-Calf Boot $49.99 The weather may be frigid but you'll step out hotter than ever in Skechers Keepsakes–Boiling Point boot. Its soft, microfiber upper is accented with a duo of logoed wooden buttons, and its fluffy faux-fur lining wraps your foot and ankle in cozy comfort.

Agilent Qualitative Boiling Point Calibration Sample 1, 6/pk $187.74 The Agilent Qualitative Boiling Point Calibration Sample 1 Contains: n-pentane, n-hexane, n-heptane, octane, nonane, decane, n-undecane, n-dodecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-eisosane, n-tetracosane, n-octacosane, n-dotriacontane, n-hexatricontane, n-tetracontane.

Boiling Point: Monitoring Cultural Shifts in the 21st Century $18.99 "More than a decade ago a groundbreaking book called The Frog in the Kettle changed what we believe about the evangelical Church and its influence in America. Subsequent books by George Barna have become must reading for church leaders and concerned Christians everywhere. Now Barna takes a fresh look at the Church--where we stand and where we are headed--at the dawn of the new millennium. With revealing statistics from cutting-edge research that illustrate the changing beliefs and attitudes in our society today, this book clearly shows that the Church is at a crucial juncture in history--a time of rapid change in which we must begin to anticipate the world's needs in order to meet them."

Ultimate Fighting Championship, Vol. 54: Boiling Point $16.96 Consisting of eight hard-hitting fights held in 2005 at the MGM Grand in Las Vegas, this event was a momentous occasion. UFC Light Heavyweight Champion Chuck Liddell finally comes face to face with the only opponent who has ever been able to defeat him: Jeremy Horn. A welterweight match-up between Georges St. Pierre and Frank Trigg offers further excitement, while the return of Randy The Natural Couture really gets the crowd going. The UFC debut of the Ultimate Fighter winner Diego Sanchez tops off this thrilling fare.

Chelsea Wall Mount Ethanol Fireplace - by Devco $349.99 This gracefully curved wall mount Chelsea model of the Anywhere Fireplace has a sleek contemporary design that will make a statement in any room. It works with any decor. The dancing flames will create a warm, mellow and luxurious atmosphere. It will create a focal point of distinction in your living room, bedroom, family room, dining room or anywhere you wish to enjoy a fire. Easy to install on the wall and all mounting hardware is included. 25inch W x 19inch H x 5.5inch D. Additional Liquid Bio-Ethanol Fuel for this Chelsea model fireplace available. Reference product code "LF12" for a 12 pack of 1 quart bottle. Color/Finish: Silver

MADISON Indoor/Outdoor Floor Standing Ethanol Fireplace $399.99 The indoor and outdoor Madison model Anywhere Fireplace will give any?áspace?áthat WOW factor. Its grand size?áand clean elegant lines is truly a show?ástopper and focal point as it sits on the floor of your living room, bedroom, patio or porch. No need to?áinstall gas lines or undergo major construction to?áget the ambiance of a large fireplace. It is specially made with an outdoor grade powder coating so you can?áchoose to?áuse it outdoors as well as indoors and the elements will not affect its satin black finish. 28inch W x 14inch H x 23.5inch D.Additional Liquid Bio-Ethanol Fuel for this Madison model fireplace available. Reference product code "LF12" for a 12 pack of 1 quart bottle. Color/Finish: Black

Routes to Cellulosic Ethanol $209 Routes to Cellulosic Ethanol

Passenger 57 / Boiling Point (Wesley Snipes Double Feature) $8.49 This collection gathers two action-packed Wesley Snipes movies.PASSENGER 57: A crackerjack airplane security agent just happens to be sharing a plane ride with a captured airline terrorist. When the terrorist escapes and attempts a mid-flight takeover, only John Cutter can stop him. Cutter finds more ways to hide and attack on the airliner than the terrorists or his band of henchmen ever imagined.BOILING POINT: A lonely Federal Treasury agent battles his own depression as he tracks a fierce and wily con-man through the shimmering streets of LA.

Boiling Point; How Coming Cultural Shifts Will Change Your Life $16.57 No Synopsis Available

The Boiling Heavens $229.99 Trey Ratcliff The Boiling Heavens - Framed Photographic Print

Density $8.99 Density

Ethanol Treatment $11.5 Gold Eagle Ethanol Treatment A new formula designed to prevent corrosion from moisture and ethanol induced water attraction Best ethanol problem fighter with more than four times the fuel system cleaner than regualr Sta-Bil Contains twice the corrosion prevention than Sta-Bil, as well as two non-alcohol water removers Designed for use with every fill up in all 2-4 stroke marine engines running gasoline, gas-oil mixtures, and ethanol blends Can also be used as a safe storage treatment in snowmobiles, motorcycles, motor homes, and all outdoor power equipment including tractors and lawn mowers 8 oz. treats up to 80 gallons and 32 oz. treats up to 320 gallons

Corn Ethanol $14.89 "In this book, Ken Glozer provides a factual evaluation of the major claims made by those who have advocated an ethanol policy for the past thirty years and answers a number of important questions. When did the policy start? How did it evolve? Are petrole

Knife, Fire and Boiling Oil $11.16 Knife, Fire and Boiling Oil

Ethanol Molecule $16.99 Ah, glorious ethanol, aka ethyl alcohol. How we love you. We would count the ways, but we can't remember them all. And even if we could, we like to count on our fingers, and we might not have the motor coordination for that right now. So we'll leave the exact number of ways we love you unsaid. But it's a lot. Our artist figured ethanol deserved slightly different treatment than our Caffeine Molecule, Capsaicin Molecule, and Chocolate Molecule designs. The ancient Egyptians may have had 17 different types of beer, but it wasn't until 1808 that Nicolas-Théodore de Saussure determined ethanol's magical chemical formula, hence our established on date for the molecular structure. This is a black, 100% cotton t-shirt. The ethyl alcohol moleculecular structure is emblazoned in white on a red emblem encircled with a golden-yellow edge and flanked by stalks of blessed grain, the fermentation of which presumably led to the alcohol molecular structure shown. Beneath is a banner of the same yellow which reads "Est. 1808 - Saussure."

A Boiling Mud Pool $39.99 A Boiling Mud Pool - Photographic Print

Boiling Mad $34.99 A clasic moster design, this mask gets added "appeal" from the pus-filled growths covering the face. Boiling Mad's fabulous face is further accented with oozing blood and framed by an ominous black hood.

Boiling Maple Sap for Sugar $49.99 Boiling Maple Sap for Sugar - Giclee Print

Plunging a Woman into Boiling Water $49.99 Plunging a Woman into Boiling Water - Giclee Print

Boiling Tea, 1617 $39.99 Ding Yunpeng Boiling Tea, 1617 - Giclee Print

Water Bubbling and Boiling in a Geyser $99.99 Water Bubbling and Boiling in a Geyser - Premium Photographic Print

Tasty Treats Anthology, Volume 3 [Man to Man, Boiling Point, Swan Song, Claiming Kristen] $15.59 No Synopsis Available

Vertigo Bio Ethanol Fireplace $436.99 This fireplace includes five ceramic artificial logs and a slim lighter - all what you need to create a worm, cozy atmosphere in your room without installation, smoke and maintenance. This fireplace uses liquid bio ethanol fuel.Materials: Black powder coated steel, tempered glassFuel required: Liquid bio ethanol fuelType of fuel: Liquid bio ethanol fuelPortableDimensions: 20 inches high x 36 inches wide x 10 inches deep

Ethanol Fuel Conditioner $9.95 Lucas Oil Ethanol Fuel Conditioner Specially developed to prevent corrosion and degradation in ethanol based fuels Protects your motor oil from the harmful side effects of alcohol combustion Cleans and maintains injectors, carburetors and valve seats It can be used in E-10, E-15, E-85, pure alcohol or any alcohol gasoline combination, even pure gasoline For use in 2-stroke and 4-stroke engines

Ethanol Molecule Flask $12.99 Ever since we realized that sugar could be fermented into ethanol, the fun began. One of our earliest organic reactions became one that fueled our parties, our perfumes, our colorings, our medicines, and even our vehicles! But we're most concerned here with its psychoactive properties when a part of a delicious adult beverage. Whether it's a fruity wine cooler with barely any ethanol or high-proof spirits, we bow down to the first human to figure this bit of chemistry out. You are awesome and if you weren't dead, we'd buy you a beer. Remember that your favorite booze is all about the ethanol. This stainless steel flask is adorned with an ethanol molecule to remind you of just that. Please imbibe responsibly, okay? We kinda like having you around. Product Specifications Stainless steel flask adorned with an ethanol molecule Celebrate organic chemistry Isn't life better with - hic! - chemistry? Drink responsibly, okay? Know your limits. # Seriously, we mean it.

Boiling Mud in the Uzon Caldera $39.99 Michael Melford Boiling Mud in the Uzon Caldera - Photographic Print

Boiling Mud Bugs $39.99 Garland R Oldham Boiling Mud Bugs - Giclee Print