Power GenerationThrough

Waves

SHOAIB AHMED SIDDIQUI & MUHAMMAD TAUQEER

• Differential warming of the earth causes pressure differences in the atmosphere, which generate winds• As winds move across the surface of open bodies of water, they transfer some

of their energy to the water and create waves• Waves travel vast distances across oceans at great speed. The longer and

stronger the wind blows over the sea surface, the higher, longer, faster and more powerful the wave is.

Where does wave energy originate?

Wave Energy Environments

The strongest winds blow between 30˚ and 60˚ in latitude.

Western coastlines at these latitudes experience the most powerful waves.

Global Wave Energy Resource Distribution (measuring the amount of power in kW contained in each linear

meter of wave front)

Wave Power: history

A bit of history… – First concepts 200 years ago, but viable schemes only in the 1970’– Increased interest for RE, and specifically for wage energy, after the energy

crisis in 1973, but insufficient money allocated to bring projects to maturity– 80’ because of oil price fall, wave energy funding reduced significantly– 90’ growing awareness of the potential of generating energy from waves

Wave Energy• The Electric Power Research Institute (EPRI) estimates that the annual

average incident wave energy off of the U.S. coastline amounts to 2100 terawatt hours per year. (A terawatt equals a trillion watts.)• Extracting 20% of that total energy at 50% conversion efficiency

would generate as much electricity as conventional hydropower currently provides – 7% of total U.S. electricity consumption, or 210 terawatt hours per year.

WHY WE NEED IT?The world's fossil fuels are dwindling whilst the amounts of CO2 in the atmosphere is increasing. What we need is an energy source that doesn't pollute, doesn't increase CO2 levels and is renewable. That's why we have wave power

How do we extract wave energy?In order to extract this energy, wave energy conversion devices must

create a system of reacting forces, in which two or more bodies move relative to each other, while at least one body interacts with the waves.

There are many ways that such a system could be configured.

Three Basic Kinds of Systems• Offshore (deals with swell energy

not breaking waves)

• Near Shore (maximum wave amplitude)

• Embedded devices (built into shoreline to receive breaking wave – but energy loss is occurring while the wave is breaking)

• The Pelamis Machine floats on the surface of the water. The rolling motion of the waves generates electricity.

•The Energy buoys are anchored to the ocean floor and generating electricity by the bobbing up and down.

•The Oscillating Water Column, water works as a piston to pump air and drive a turbine to generate power.

HOW DEVICES WORK

10

Oscillating Water Column

12

Point Absorber Buoy

The Aguçadoura Wave Farm was the world's first wave farm. It was located 5 km (3 mi) offshore near the north Port in Portugal. The farm was designed to use three Pelamis Wave Energy converter to convert the motion of the Ocean surface waves into electricity, 2.25 MW in total installed capacity. The farm was officially opened on 23 September 2008

Examples

PB150 PowerBuoy with peak-rated power output of 150 kW. USA

750 kW Pelamis Wave Energy Converter, Scotland

The Future: Wave farms

IMPLEMENTATION IN PAKISTAN

Electricity shortfall reaches 5500 MW in Pakistan

• Load shedding duration has increased as difference in the supply and demand of power hit 5,500 MW a mid ongoing intense heatwave in most parts of the country.• Currently, electricity generation is 15,500

MW against the demand of 21,000 MW.

Benefits of Wave Energy • Available 24/7 on 365 days - therefore power produced from them is

much steadier and more predictable – waves can be accurately predicted 48 hours in advance and therefore forecast energy output (BUT irregularity in wave ampitude, and direction)• Good data on waves from wave monitoring bouys• Wave energy contains 1000 times the kinetic energy of wind (can produce

the same amount of power in less space)• Wave power does not produce greenhouse gases.• The energy is free - no fuel needed, no waste produced.

CONCLUSION• Ocean waves are both clean and

renewable sources of energy with a tremendous worldwide potential of generating electricity. • If fully exploited, about 40% of

the world’s power demand could be supplied by this resource – equivalent to as much as 800 nuclear power plants.

At the University of Edinburgh, Prof. Salter developed what is known today as Salter’s Duck. Salter’s Duck looked like very large boxes that were attached to the ocean floor. As the waves moved them back and forth, the mechanical energy became electrical energy, which drove a generator. Salter’s Duck was able to capture 90 percent of the wave motion and 90 percent of that could be turned into electrical energy, which is very impressive. In addition, at the time the Duck was completed, the cost of the electricity was the same as nuclear power

Difference between tidal and wave energy• Tides generated by the combination of the moon and sun’s

gravitational forces• Greatest affect in spring when moon and sun combine forces• Tides are driven by the moon's rotation around the earth

• Wave energy• The prime energy source of wave energy is the sun. The sun

heats the Earth's surface, the resulting temperature differences create winds and the wind blowing over ocean surfaces creates waves.

• ------------------------------------------------------• The main difference is probably the period between the two -

tides have a period of several hours, since there are one or two tidal peaks in a day, because it takes a while for the moon to get around the earth. Waves have a short period of just seconds.

There were a series of energy crises between 1967 and 1979 caused by problems in the Middle East but the most significant started in 1973 when Arab oil producers imposed an embargo.The decision to boycott America and punish the west in response to support for Israel in the Yom Kippur war against Egypt led the price of crude to rise from $3 per barrel to $12 by 1974.The price of petrol rocketed, making all transport more expensive. There was even talk in Britain of rationing using coupons left over from the second world war.

• the best wave generator technology in place in the United Kingdom is producing energy at an average projected/assessed cost of 7.5 cents kWh