WAVE ENERGY

• 1799: First patent of a device designed to use ocean waves to generate power

• 1910: First oscillating water column was built by Bochaux- Praceique to power his house

• 1940s: Yoshio Masuda experimented with many concepts of wave power

• 2004: Wave power was delivered to an electrical grid for the first time

• Salter’s Duck design

• Could stop 90% of wave motion and could convert 90% of that to electricity

• Shut down because of an error in calculating the cost, which wasn’t discovered until 2008, and the program had been shut down in 1982

• The “duck” device bobs back and forth as waves pass, this motion moves a pendulum that is connected to a generator that produces electricity

• Advantages

• The energy is free – no fuel needed, no waste produced

• Not expensive to operate and maintain

• Can produce a great deal of energy

• Disadvantages

• Depends on the waves – sometimes you’ll get loads of energy, sometimes almost nothing

• Needs a suitable site, where waves are consistently strong

• Some designs are noisy. But then again, so are waves, so any noise is unlikely to be a problem

• Must be able to withstand

Environmental impact

– Noise pollution

– Displace productive fishing sites

– Change the pattern of beach sand nourishment

– Alter food chains and disrupt migration patterns

– Offshore devices will displace bottom-dwelling organisms where they connect into the

– Potential of 1,500 – 7,500 TWh/year

– 10 and 50% of the world’s yearly electricity demand

– IEA (International Energy Agency)

– 200,000 MW installed wave and tidal energy power forecast by 2050

– Power production of 6 TWh/y

– Load factor of 0.35

– DTI and Carbon Trust (UK)

– “Independent of the different estimates the potential for a pollution free energy generation is enormous.”

OCEAN THERMAL ENERGY CONVERSION

OTEC is a way to generate electricity using the temperature difference of sea water at different depth.

OTEC utilizes the world’s largest solar radiation collector - the ocean. The ocean contains enough energy power all of the world’s

In 1881 Jacques Arsene d'Arsonval, a French physicist, was the first to propose tapping the thermal energy of the ocean.

In 1930 Arsonval built an experimental open cycle OTEC system at Matazas Bay, Cuba. The system produce 22 KW of electricity.

Oceans surface waters acts as heat source and the cold water at 1,000 meters depth acts as heat sink.

i. Eco- friendly

ii. Minimal maintenance costs compared to other power production plants

iii. Provide air conditioning to buildings within the OTEC plant

iv. Fresh water - first by-product is fresh water. A small 1 MW OTEC is capable of producing some 4,500 cubic meters of fresh water per day, enough to supply a population of 20,000 with fresh water

v. Open cycle OTEC systems can produce desalinated water which is very important in third-world countries

vi. Chilled soil agriculture- cold seawater flowing through underground pipes, chills the surrounding soil. Thereby allowing many plants evolved in temperate to be grown in subtropics due to temp. difference in the plant roots in cool soil and plant leaves in warm air

DISADVANTAGES

i. OTEC-produced electricity at present would cost more than electricity generated from fossil fuels at their current costs.

ii. OTEC plants must be located where a difference of about 20º C occurs year round. Ocean depths must be available fairly close to shore-based facilities for economic

iii. No energy company will put money in this project because it only had been tested in a very small scale.

iv. Construction of OTEC plants and lying of pipes in coastal waters may cause localized damage to reefs and near-shore marine ecosystems.

future

The fossil fuels will in the near future be consumed, so we had to find some alternative energy sources. OTEC is a source, which uses the renewable solar collector, the sea, instead of an artificial collector.

The problem is that this investment will be more expensive than the fossil fuels power plants, and it will take a long time before anyone will put some money in this project and outrival the now existing plants.

Osmotic power Salinity gradient 2,000 TWh

Ocean thermal energy Thermal gradient 10,000 TWh

Wave energy 8,000–80,000 TWh

Source: IEA-OES, Annual Report 2007