Rain Energy

The testing apparatus controlled drop size, frequency, and height, as drops of water fell and impacted a piezoelectric material at the base. Credit: Romain Guigon, et al.

Researchers who study energy harvesting see energy all around us – we just need to find a way to capture that energy. One of the latest energy harvesting techniques is converting the mechanical energy from falling raindrops into electricity that can be used to power sensors and other electronics devices.

Scientists from CEA/Leti-Minatec, an R&D institute in Grenoble, France, specializing in microelectronics, have recently developed a system that recovers the vibration energy from a piezoelectric structure impacted by a falling raindrop. The system works with raindrops ranging in diameter from 1 to 5 mm, and simulations show that it’s possible to recover up to 12 milliwatts from one of the larger “downpour” drops.

“Our work could be considered as a good alternative to power systems in raining outdoor environments where solar energy is difficult to exploit,” Thomas Jager told PhysOrg.com. He explained that the system could be used for both mobile outdoor devices as well as indoor power. “For example, we intend to develop remote sensor nodes in cooling towers, but abandoned sensor networks are also one of the foreseen applications for this type of system.”

As Jager and coauthors Romain Guigon, Jean-Jacques Chaillout, and Ghislain Despesse explain in a recent issue of Smart Materials and Structures, the physics of how a raindrop impacts a surface is not fully understood. However, to build a rain energy harvesting system, the important part is to estimate the recoverable energy during the impact.

When a raindrop impacts a surface, it produces a perfectly inelastic shock. The amount of energy generated by the impact can then be estimated using a mechanical-electric model.

To capture the raindrops’ mechanical energy, the scientists used a PVDF (polyvinylidene fluoride) polymer, a piezoelectric material that converts mechanical energy into electrical energy. When a raindrop impacts the 25-micrometer-thick PVDF, the polymer starts to vibrate. Electrodes embedded in the PVDF are used to recover the electrical charges generated by the vibrations.

The group experimented with raindrops of different sizes, falling heights, and speeds. They found that slow falling raindrops generate the most energy because raindrops falling at high speeds often lose some energy due to splash. By using a micropump to generate and test the properties of raindrops, the researchers demonstrated that, for low drop heights, the electrical energy is proportional to the square of the drop’s mechanical energy, while voltage and mechanical energy are directly proportional.

The largest raindrops caused the largest vibrations on the PVDF, and therefore generated the greatest amount of electrical energy. The researchers demonstrated that their system could generate 1 microwatt of continuous power as a worst-case scenario, while simulations showed that a single large raindrop might generate up to 12 milliwatts of power.

“The recoverable energy depends directly on the size of the piezoelectric membrane, the size of raindrops, and their frequency,” Jager explained. “The available energy per drop varies between 2 µJ from 1 mJ depending on its size.

“The corresponding instantaneous converted power starts from a few µW up to 10 mW for a converter area of a several square centimeters. An interesting figure to keep in mind could also be the available rain power per year in common France regions with a continental climate: almost 1 Wh per square meter per year.”

In the future, the scientists plan to develop a method to store the electrical power to provide a steady current for practical use.

More information: Guigon, Romain, Chaillout, Jean-Jacques, Jager, Thomas, and Despesse Ghislain. “Harvesting raindrop energy: theory” and “Harvesting raindrop energy: experimental study.” Smart Mater. Struct. 17 (2008) 015038-9.
Copyright 2008 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

Wave Energy

Waves are generated by wind passing over the sea surface. As long as the waves propagate slower than the wind speed just above the waves, there is an energy transfer from the wind to the waves. Both air pressure differences between the upwind and the lee side of a wave crest, as well as friction on the water surface by the wind shear stress causes the growth of the waves.[4]

Wave height is determined by wind speed, the duration of time the wind has been blowing, fetch (the distance over which the wind excites the waves) and by the depth and topography of the seafloor (which can focus or disperse the energy of the waves). A given wind speed has a matching practical limit over which time or distance will not produce larger waves. This limit is called a "fully developed sea."

In general, larger waves are more powerful but wave power is also determined by wave speed, wavelength, and water density.

Oscillatory motion is highest at the surface and diminishes exponentially with depth. However, for standing waves (clapotis) near a reflecting coast, wave energy is also present as pressure oscillations at great depth, producing microseisms.[4] These pressure fluctuations at greater depth are too small to be interesting from the point of view of wave power.

The waves propagate on the ocean surface, and the wave energy is also transported horizontally with the group velocity. The mean transport rate of the wave energy through a vertical plane of unit width, parallel to a wave crest, is called the wave energy flux (or wave power, which must not be confused with the actual power generated by a wave power device).

Nuclear Power Plant for Future

The Writer is study how's the power plant demand in 2050. he studied this calculation at 1997-1998. This e-book explain how's the human look for the energy source in the future. The energy resource is more valuable than others. Many human will die to get and take over the power energy.

The nuclear international role will change for the energy needs. .........

Contains:
In 1997-1998, I made an estimate of how many nuclear plants would be needed by 2050. It reflects an economy that is directed to provide the energy necessary to meet basic human needs, especially for the developing regions. The initiative required is not unlike what the U.S. government did under Roosevelt to bring electric power to rural areas; to provide transportation by building roads and highways, canals, railroads, and airlines; to develop water supplies and irrigation systems, to provide telephone service, medical, and hospital services; and many other programs that were essential to lift regions out of poverty. That is, to meet the needs of people outside of the mainstream of economic life, even if those people are the farmers providing our food and clothing, miners providing our coal and steel, and so on. However, as economist Lyndon LaRouche has proposed, we need to do more to meet those needs, both within the United States and for the developing world, to bring those people into the economic mainstream, instead of leaving them just as cheap sources of our labor and raw materials.
…
The projections I made for nuclear energy in 2050 simply took the role of nuclear energy to provide for roughly one third of the energy demand in 2050, which was taken to grow by about a factor of 3 from 2000. But, of course, that begs the question: Can fossil fuels continue to provide energy at the same level, or a moderate increase as today, to produce about one third of the energy demand in 2050? And can hydro, wind energy, and other alternatives (for example, tidal and wave energy), provide the other third, also the equivalent of 100 percent of today’s total energy use?

......

Download Nuclear 2050

The Wind Energy

Wind Power

Societies have taken advantage of wind power for thousands of years. The first known use was in 5000 BC when people used sails to navigate the Nile River. Persians had already been using windmills for 400 years by 900 AD in order to pump water and grind grain. Windmills may have even been developed in China before 1 AD, but the earliest written documentation comes from 1219. Cretans were using "literally hundreds of sail-rotor windmills [to] pump water for crops and livestock."

The Windmill

The Dutch were responsible for many refinements of the windmill, primarily for pumping excess water off land that was flooded. As early as 1390, they had connected the mill to "a multi-story tower, with separate floors devoted to grinding grain, removing chaff, storing grain, and (on the bottom) living quarters for the windsmith and his family." Its popularity spread to the point that there were 10,000 windmills in England. But perfecting the windmill's efficiency to the point that it "had all the major features recognized by modern designers as being crucial to the performance of modern wind turbine blades" took almost 500 years. By then, applications ranged from saw-milling timber to processing spices, tobacco, cocoa, paints, and dyes.

The windmill was further refined in the late 19th century in the US; some designs from that period are still in use today. Heavy, inefficient wooden blades were replaced by lighter, faster steel blades around 1870. Over the next century, more than six million small windmills were erected in the US in order to aid in watering livestock and supplying homes with water during the development of the West. The first large windmill to produce electricity was the "American multi-blade design," built in 1888. Its 12-kilowatt capabilities were later superceded by modern 70-100 kilowatt wind turbines.

Wind Energy Sources

Today, people are realizing that wind power "is one of the most promising new energy sources" that can serve as an alternative to fossil fuel-generated electricity. As of 1999, global wind energy capacity topped 10,000 megawatts, which is approximately 16 billion kilowatt-hours of electricity. That's enough to serve over 5 cities the size of Miami, according to the American Wind Energy Association. Five Miamis may not seem significant, but if we make the predicted strides in the near future, wind power could be one of our main sources of electricity.

"With today's technology, wind energy could provide 20% of America's electricity (or about the amount nuclear power provides) with turbines installed on less than 1% of its land area. And within that area, less than 5% of the land would be occupied by wind equipment—the remaining 95% could continue to be used for farming or ranching." By the year 2010, 10 million average American homes may be supplied by wind power, preventing 100 million metric tons of CO2 emissions every year. Lessening our dependence on fossil fuels is critical to the health of all living things, and wind energy can do just that.

"The 3 billion kWh of electricity produced by America's wind machines annually displace the energy equivalent of 6.4 million barrels of oil and avoid 1.67 million tons of carbon emissions, as well as sulfur and nitrogen oxide emissions that cause smog and acid rain." In other words, "more wind power means less smog, acid rain, and greenhouse gas emissions."

Windmills may have been around for almost 1500 years, but it was not imagined that wind power would become affordable enough to compete with fossil fuels. Indeed it has. In fact, many utility services around the world offer wind-generated electricity at a premium of 2 to 3 cents per kWh. If a household used wind power for 25% of its needs, it would spend only $4 or $5 dollars per month for it and the price is still dropping.

Compare this to 4.8 to 5.5 cents per kWh for coal or 11.1 to 14.5 cents per kWh for nuclear power. Wind energy is therefore "cheaper than any other new electric generation except natural gas…[which] emits one pound of greenhouse gases for every kilowatt-hour of electricity it generates." The success of this energy is in part due to the fact that its costs have gone "down by more than 80% since the early 1980s." Even lower prices are expected, as "industry analysts see the cost dropping by an additional 20 percent to 40 percent by 2005."

Electricity from wind

Germany, the US, Spain, Denmark, and India are among the world's leading nations in the acquisition of wind energy. According to Chris Flavin, a speaker at the World Oil Forum held in Denver, Colorado, on October 30, 1998, "Navarro, Spain, is utilizing wind power to generate 23% of its electricity needs." Denmark now generates 8 percent of its electricity from wind power. Flavin, a vice president and senior energy policy analyst at the Worldwatch Institute, reported that wind generated energy is growing in leaps and bounds.

In fact, according to Worldwatch Institute Online, "The world added 2,100 megawatts of new wind energy generating capacity in 1998, a new all-time record, and 35% more than was added in 1997. Wind power is now the world's fastest growing energy source and has also become one of the most rapidly expanding industries, with sales of roughly $2 billion in 1998." Major offshore developments are likely in northern European waters in the early part of the next century.

This will be the next major step for this technology and will result in a dramatic increase in decentralized electricity generation. Offshore wind has the potential to deliver substantial quantities of energy at a price that is cheaper than most of the other renewable energies, as wind speeds are generally higher offshore than on land.

--------

History

The Alternative Energy Institute (AEI) was formed in 1977 at West Texas State University, Texas, USA, as an outgrowth of wind energy research begun in 1970. AEI's primary emphasis has been placed on wind energy, though certain research and education are also on solar energy. Recognized both nationally and internationally, AEI is proud to be the major information resource of wind energy for the State of Texas.

Note: the wind energy has low efficiency for power generation but it will running continuously as long the wind flow which influenced by season and solar movement.