Wind Power History...

The wind is a free, clean, and inexhaustible energy source. It has served humankind well for many
centuries by propelling ships and driving wind turbines to grind grain and pump water. Denmark was
the first country to use wind for generation of electricity. The Danes were using a 23-m diameter wind
turbine in 1890 to generate electricity. By 1910, several hundred units with capacities of 5 to 25 kW were
in operation in Denmark (Johnson, 1985). By about 1925, commercial wind-electric plants using twoand
three-bladed propellers appeared on the American market. The most common brands were
Wincharger (200 to 1200 W) and Jacobs (1.5 to 3 kW). These were used on farms to charge storage
batteries which were then used to operate radios, lights, and small appliances with voltage ratings of 12,
32, or 110 volts. A good selection of 32-VDC appliances was developed by the industry to meet this
demand.
In addition to home wind-electric generation, a number of utilities around the world have built
larger wind turbines to supply power to their customers. The largest wind turbine built before the late
1970s was a 1250-kW machine built on Grandpa’s Knob, near Rutland, Vermont, in 1941. This turbine,
called the Smith-Putnam machine, had a tower that was 34 m high and a rotor 53 m in diameter. The
rotor turned an ac synchronous generator that produced 1250 kW of electrical power at wind speeds
above 13 m=s.
After World War II, we entered the era of cheap oil imported from the Middle East. Interest in wind
energy died and companies making small turbines folded. The oil embargo of 1973 served as a wakeup
call, and oil-importing nations around the world started looking at wind again. The two most important
countries in wind power development since then have been the U.S. and Denmark (Brower et al., 1993).
The U.S. immediately started to develop utility-scale turbines. It was understood that large turbines
had the potential for producing cheaper electricity than smaller turbines, so that was a reasonable
decision. The strategy of getting large turbines in place was poorly chosen, however. The Department of
Energy decided that only large aerospace companies had the manufacturing and engineering capability
to build utility-scale turbines. This meant that small companies with good ideas would not have the
revenue stream necessary for survival. The problem with the aerospace firms was that they had no desire
to manufacture utility-scale wind turbines. They gladly took the government’s money to build test
turbines, but when the money ran out, they were looking for other research projects. The government
funded a number of test turbines, from the 100 kW MOD-0 to the 2500 kW MOD-2. These ran for brief
periods of time, a few years at most. Once it was obvious that a particular design would never be cost
competitive, the turbine was quickly salvaged.
Denmark, on the other hand, established a plan whereby a landowner could buy a turbine and sell the
electricity to the local utility at a price where there was at least some hope of making money. The early turbines were larger than what a farmer would need for himself, but not what we would consider utility
scale. This provided a revenue stream for small companies. They could try new ideas and learn from
their mistakes. Many people jumped into this new market. In 1986, there were 25 wind turbine
manufacturers in Denmark. The Danish market gave them a base from which they could also sell to
other countries. It was said that Denmark led the world in exports of two products: wind turbines and
butter cookies! There has been consolidation in the Danish industry since 1986, but some of the
companies have grown large. Vestas, for example, has more installed wind turbine capacity worldwide
than any other manufacturer.
Prices have dropped substantially since 1973, as performance has improved. It is now commonplace
for wind power plants (collections of utility-scale turbines) to be able to sell electricity for under four
cents per kilowatt hour.
Total installed worldwide capacity at the start of 1999 was almost 10,000 MW, according to the trade
magazine Wind Power Monthly (1999).

Energy Storage Systems.

Energy storage technologies are of great interest to electric utilities, energy service companies,
and automobile manufacturers (for electric vehicle application). The ability to store large amounts of
energy would allow electric utilities to have greater flexibility in their operation because with this
option the supply and demand do not have to be matched instantaneously. The availability of the
proper battery at the right price will make the electric vehicle a reality, a goal that has eluded
the automotive industry thus far. Four types of storage technologies (listed below) are discussed in
this section, but most emphasis is placed on storage batteries because it is now closest to being
commercially viable. The other storage technology widely used by the electric power industry,
pumped-storage power plants, is not discussed as this has been in commercial operation for more
than 60 years in various countries around the world.
. Flywheel storage
. Compressed air energy storage
. Superconducting magnetic energy storage
. Battery storage

Ultrasonic range finder using arduino...

Ultrasonic range finder using 8051 mictrocontroller has been already published by me in this website. This time it is an ultrasonic range finder using arduino. HC-SR04 ultrasonic range finder module is used as the sensor here. The display consists of a three digit multiplexed seven segment display. This range finder can measure up to 200 cm and has an accuracy of 1cm. There is an option for displaying the distance in inch also. Typical applications of this range finder are parking sensors, obstacle warning system, level controllers, terrain monitoring devices etc.