Solar Energy: Electricity Out Of A Helicopter Turbine

The mountains of Armenia seem to have been created for electric power stations working on solar energy. The scientists at the Radio Physical Research Institute have chosen a ground on Aragats mountain, which is 40 km to the west of Yerevan and situated 1750m above sea level. Southern mountain Sun is a good source of cheap energy. It rises 73 degrees above the horizon in summer and the atmosphere layer absorbing radiation in the mountains is thinner.
      
The new electric power station "AREV" (the Armenian for "Sun") is a big spherical mirror made of glass and fixed with props on the slope of the mountain. The mirror has the slope of 40 degrees to the horizon in order to catch the light all through the year. The sunbeams fall on the concave mirror surface, than get reflected from its walls and focus on a small circle in side the sphere. The area of the maximum heat with the temperature rising above 800 C moves along the circle following the Sun. Together with this hot spot a special heat exchange device absorbing the heat moves over the mirror.

The device is a bell being 3m in diameter with double walls, where a compressor supercharges air to. Heating up in the bell, the air expands and revolves the vanes of the turbine, which is connected with the electro generator. By the way, in this project the scientists use a turbine of a helicopter that has already worked its resource in the air. A photo sensor automatically operates all this mechanical construction installed on a tower. Such an electric power station with the power of 100 kilowatt produces rather cheap energy - 0.5 cent per kilowatt per hour. The efficiency of the station is forty up to fifty per cent. AREV will work ten hours per day in summer and eight hours per day in winter.
      
"The electric power station AREV-100 is the first experimental sample of little power; the diameter of its spherical mirror is thirty-six meters. The next installation with a seventy-five meter mirror will be much more powerful, i.e. 1.5 megawatt", - says Paris Herouni, the constructor of the station AREV.
      
At the summit in Okinawa in June, 2000, the G-8 leaders pointed out two world global problems that the mankind is facing, namely, information technologies development and use of renewable energy resources - sun heat, wind energy, water and biomass. This raw material for energy production will replace coal, oil, gas and uranium, the resources of which are limited. That is why scientists from all over the world are working on the projects for sun energy usage, which is the most efficient of all the so-called unconventional power-engineering branches.wind generator,home wind generator,wind energy,wind turbines ,generators

Recycling wind turbines

The development of wind power promises much in terms of providing us with renewable energy for the future and wind turbines could be the most effective way to harness that power. Danish researchers now suggest that in order to assess the overall environmental impact of wind power, however, the finite lifespan of wind turbines and the need to replace and recycle them must be taken into account. Such an assessment will help policy makers and the industry to develop the green credentials of wind power more effectively.

Writing today in the Inderscience publication, International Journal of Technology, Policy and Management, the researchers describe a prospective case study for managing environmental aspects of wind turbines. Their suggested plan for assessing the overall impact of installing and operating wind turbines should be adopted by the industry and policy makers, they say.

Wind turbines are one of the most environmentally sound technologies for producing electricity, explain the researchers. However, the removal and recycling phase of wind turbines has been identified as a blind spot in assessing their overall environmental impact. Most studies have ignored this phase and focused entirely on their operation and in some cases the production and installation of wind turbines.

Foresight and innovation analysts Per Dannemand Andersen and Mads Borup working with wind energy expert Thomas Krogh have devised a method for mapping and mitigating the negative environmental impacts of wind turbines which considers the future removal and recycling of offshore wind turbines up to the year 2050. By combining life-cycle assessment and taking into account future developments in this area of renewable energy, the team hopes that the wind power industry will be able to minimize any potential negative impact of their use.

Because the wind-turbine industry is relatively young, there is only a limited amount of practical experience on the removal and recycling of wind turbines," Dannemand Andersen says, "It is likely to take more than 20 years before a substantial amount of practical experience regarding the dismantling, separation, recycling, disposal, etc., of wind-power systems is gained."

The present study has developed an interactive and process-oriented method for investigating the environmental impact of wind turbines removal and recycling. The team hopes that the industry will adopt their approach and so find ways to reduce any negative impacts of wind power.

From:http://www.allwindenergy.com/news/news.htm

Special wind turbines

One E-66 wind turbine at Windpark Holtriem, Germany carries an observation deck, open for visitors to see. Another turbine of the same type, with an observation deck, can be located in Swaffham, England.

A series of floating wind turbines utilizing the Magnus Effect are in development in Canada by Magenn Power. They deliver power to the ground by a tether system.

Wind turbines may also be used in conjunction with a solar collector to extract the energy due to air heated by the Sun and rising through a large vertical solar updraft tower.
Wind machines were used for grinding grain in Persia as early as 200 B.C. This type of machine was introduced into the Roman Empire by 250 A.D. By the 14th century Dutch windmills were in use to drain areas of the Rhine River delta. In Denmark by 1900 there were about 2500 windmills for mechanical loads such as pumps and mills, producing an estimated combined peak power of about 30 MW. The first windmill for electricity production was built in Cleveland, Ohio by Charles F Brush in 1888, and in 1908 there were 72 wind-driven electric generators from 5 kW to 25 kW. The largest machines were on 24 m (79 ft) towers with four-bladed 23 m (75 ft) diameter rotors.

By the 1930s windmills were mainly used to generate electricity on farms, mostly in the United States where distribution systems had not yet been installed. In this period, high-tensile steel was cheap, and windmills were placed atop prefabricated open steel lattice towers. A forerunner of modern horizontal-axis wind generators was in service at Yalta, USSR in 1931. This was a 100 kW generator on a 30 m (100 ft) tower, connected to the local 6.3 kV distribution system. It was reported to have an annual load factor of 32 per cent, not much different from current wind machines.

China Suggests Capping Wind Power On-grid Tariffs

China should cap wind power on-grid tariffs in order to bring tariffs set by local governments into line with those set through the national public bidding system, according to a report recently released that was compiled by the National Development and Reform Commission's Energy Bureau.
While the report did not propose any specific price caps, the adoption of such a system would serve as a blow to foreign developers in China's wind energy market who have relied on favorable local on-grid tariffs for small-scale wind power projects in order to generate acceptable profits.
Wind power projects with over 50 megawatts of capacity need to go through a public bidding process, organized by the NDRC, in which low power tariffs are the primary criterion for winning. Tariffs for projects awarded by local governments tend to be RMB 0.1 ($0.013) per kilowatt hour higher than those awarded through the central government's bidding system.
Beijing aims to drive down the price of wind generated power in order to encourage its use, which it believes can be achieved through such a competition bidding system as well as the localization of wind power equipment production.
However, such an approach has benefited deep-pocketed state-owned power companies that have emission-reduction targets to fulfill. Such companies tend to submit uneconomic bids in order to win the project, and then leave the wind farm either undeveloped or equipped with low-quality equipment in order to cut costs.
By going through local governments though, foreign companies can secure better power on-grid tariff rates as well as more control over key aspects of their projects, such as the location of the wind farm. Such important issues can sometimes make or break a deal, Alberto Mendez, the China general manager of Spain's Gamesa, one of the world's largest wind turbine makers and wind farm developers, said at an industry forum held in May.
At present, wind farm projects planned or awarded via tenders by the central government have a combined power generation capacity of 2,000 MW, while those handled by local governments have a combined capacity of almost 8,000 MW.
Industry insiders have long called for a premium rate for wind power that would be set around RMB 0.25 ($0.03) per kWh higher than power from coal-fired plants in order to create further incentives to attract investors.
The report also said that China should adjust its wind power development targets at an appropriate time as, if current trends continue, the country is likely to achieve a wind power capacity triple that of its current 2020 target of 30,000 MW.
China could even achieve 120,000 MW of installed wind power capacity by 2020 if the country's policy environment is improved, according to the report.
The NDRC currently expects over 2,000 MW of wind power generating capacity to go into operation this year, adding to the 2,600 MW of wind power generating capacity that was installed last year.
Of the total capacity added last year, Goldwind from northwestern China's Xinjiang Autonomous Region accounted for 33.2 percent of the addition, followed by Denmark's Vestas, one of the world's largest producers of wind turbines, with 23.5 percent. Gamesa accounted for 15.8 percent of newly installed capacity, while U.S.-based GE accounted for 12.6 percent, according to the China Wind Energy Association.

China to amend law to reduce energy consumption

Source:Xinhua
Under heavy pressure to cut energy consumption, China is now turning the spotlight on to construction projects, the transportation sector and government buildings.
China's top legislature on Sunday began deliberating a draft amendment to the Law on Conserving Energy, which details measures to avoid energy waste in the three areas to improve energy efficiency and cut pollution emissions.
Under a five-year plan to 2010, China pledged to cut energy consumption per unit of gross domestic product (GDP) by 20 percent, or four percent each year. But, the consumption actually fell by just 1.23 percent last year.
"Achieving the target is highly problematic. Energy consumption in some areas and industries just keeps rising," Fu Zhihuan, chairman of the Financial and Economic Committee of the National People's Congress (NPC), told lawmakers in a report.
Fu said energy consumption in these three areas has been rising rapidly. He said they had not been given enough attention and were the "weak link" in China's energy-saving campaign.
Official statistics show that construction accounted for 27.5 percent of China's total energy consumption in 2005, transportation 16.3 percent and government buildings 6.7 percent.
The draft, tabled to lawmakers for a first reading, says that construction project must reach obligatory energy-saving standards and buildings and plants already built will be subject to regular inspection by building authorities.
It also says Chinese cities will gradually replace antiquated central heating with modern household heating systems that can be individually regulated.
Other energy-saving measures include strict control of the indoor temperature of public buildings and restrictions on decorative lighting for large buildings.
China has built 1.06 billion square meters of energy efficient buildings, but the figure represents only 7 percent of the total floor space of existing buildings in urban China, statistics from the Ministry of Construction show.
According to a survey by the ministry in 30 regions, the four municipalities of Beijing, Shanghai, Tianjin and Chongqing are doing relatively well in implementing energy saving codes, but other regions are a long way behind in technological standards and government supervision.
The draft, which almost doubles the articles of the original law, also requires governments at all levels to increase investment in public transport, improve services and encourage the public to use public transport.
China, once known as the kingdom of bicycles, has overtaken Japan to become the world's second largest auto market after the United States with Chinese people's love for private vehicles showing no sign of abating. The number of privately owned motor vehicles rose 18.8 percent year-on-year to 22 million in China in 2006.
The draft says that the Chinese government encourages the development, production, selling and use of environmental-friendly vehicles and new types of automobile propelled by new clean fuel, in an effort to save energy and cut emissions.
The draft also requires governments at all levels to make energy-saving plans for their office buildings and make the details public.
It bans government from purchasing high energy-consuming equipment, saying that energy-saving products should be the priority in government procurement.
The State Council, or the cabinet, in early June issued a circular, ordering that the temperature of all air-conditioned public rooms in China should be kept at no lower than 26 degrees Celsius.
All government agencies, associations, groups, companies and private owners in public buildings should strictly comply with this rule, according to the circular.
The draft also highlighted energy efficiency in the industrial sector, saying that China will continue to push forward industrial restructuring and technical innovation to gradually weed out outdated production methods.
The six high energy-consuming and highly polluting industries -- electricity, steel, nonferrous metals, construction materials, oil processing and chemicals -- which account for nearly 70 percent of energy consumption and sulfur dioxide discharges of the entire industrial sector, grew by 20.6 percent in the first quarter of 2007, 6.6 percentage points higher than the same period a year earlier.
The government will issue preferential policies in financial investment, taxation, price, credit and government procurement to encourage energy-saving, according to the draft.
The Chinese government has announced a series of measures to cut energy consumption this year in order to meet strict energy efficiency and pollutant reduction targets, which it failed last year.
The State Council has set up a leading group head by Premier Wen Jiabao to oversee the national efforts for energy efficiency and discharge reduction.
Experts believe that by sharpening rules and punishments in the nine-year-old law, China will be able to achieve the widely publicized targets by 2010 and move in the direction of sustainable development.
"If China fails to significantly reduce energy consumption this year, it will be almost impossible for the country to reach the goal by 2010," said Dai Yande, deputy director of the energy institution under the NDRC.
"The draft amendment, which come at a critical moment, will provide a strong legal basis for China to further intensify its energy-saving campaign," Dai said.

Cyclic stresses and vibration

Cyclic stresses fatigue the blade, axle and bearing material failures were a major cause of turbine failure for many years. Because wind velocity often increases at higher altitudes, the backward force and torque on a horizontal-axis wind turbine (HAWT) blade peaks as it turns through the highest point in its circle. The tower hinders the airflow at the lowest point in the circle, which produces a local dip in force and torque. These effects produce a cyclic twist on the main bearings of a HAWT. The combined twist is worst in machines with an even number of blades, where one is straight up when another is straight down. To improve reliability, teetering hubs have been used which allow the main shaft to rock through a few degrees, so that the main bearings do not have to resist the torque peaks.

When the turbine turns to face the wind, the rotating blades act like a gyroscope. As it pivots, gyroscopic precession tries to twist the turbine into a forward or backward somersault. For each blade on a wind generator's turbine, precessive force is at a minimum when the blade is horizontal and at a maximum when the blade is vertical. This cyclic twisting can quickly fatigue and crack the blade roots, hub and axle of the turbines.

Vertical axis
12 m Windmill with rotational sails in the Osijek, Croatia
12 m Windmill with rotational sails in the Osijek, Croatia

Vertical-axis wind turbines (or VAWTs) have the main rotor shaft running vertically. Key advantages of this arrangement are that the generator and/or gearbox can be placed at the bottom, near the ground, so the tower doesn't need to support it, and that the turbine doesn't need to be pointed into the wind. Drawbacks are usually pulsating torque that can be produced during each revolution and drag created when the blade rotates into the wind. It is also difficult to mount vertical-axis turbines on towers, meaning they must operate in the often slower, more turbulent air flow near the ground, resulting in lower energy extraction efficiency.