Lecture 5 Review
The subject of lecture 5 was Ocean Energy. The ocean has a great
potential for energy extraction, as it is very energy dense. The
earth's surface is 70% water, so the amount of solar energy incident on
the ocean is much larger than on land, and is equivalent to 250 billion
barrels of oil per day (3000 times larger than the current output of
oil). Conservative estimates predict that up to 25% of the world's
energy needs could come from the ocean, so they are definitely a
renewable energy source that deserves attention.
There are
four main ways of extracting energy from
the
Ocean, from wave energy, tidal energy, current energy and thermal
energy. We learnt that the typical amount of energy that can be
extracted from a meter of wave crest is about 10 times higher that the energy in a square meter of wind because water density is much higher than
the air (areas of the world oceans have upwards of 90 kW/m).
However the vast majority of this energy doesn't reach our coasts as it
dissipates through wave breaking and interaction with the seabed. Hence
the most energy profitable areas are offshore, before this interaction can take place.
In
terms of wave energy extraction there are 5 options that we looked at:
- Oscillating Water Column, Overtopping, Surge, Attenuator and Point
Absorber. Examples were given of each, and Pelamis (attenuator) was
highlighted as the only commercially active Wave Energy Converter. We
also looked at several of Resolute Marine's concepts, which were all
point absorbers. Another advantage of wave energy is that it's levels
are in synch with seasonal energy demand in the US - the waves get
larger as the heating energy demand increases in the winter.
Tidal
energy is only economically viable at about 20 sites around the world,
due to the need for large tidal variations combined with specific
geographical requirements. It's maximum potential contribution to the
US energy need is between 1-2%, and it is only generating power for 35%
of the day. However it's predictability means that this can be planned
for, and still utilized effectively.
The development of wave energy is currently at the point as wind energy was 25 years ago. Now wind energy has converged on one design, and more and more commercial wind farms are being built. The process for wave energy should be swifter, given the lessons that have been learnt from wind. So ocean energy has a vast potential that hopefully we can start using soon.
Hosted by Professor Dick K.P. Yue
There are
four main ways of extracting energy from
the
Ocean, from wave energy, tidal energy, current energy and thermal
energy. We learnt that the typical amount of energy that can be
extracted from a meter of wave crest is about 10 times higher that the energy in a square meter of wind because water density is much higher than
the air (areas of the world oceans have upwards of 90 kW/m).
However the vast majority of this energy doesn't reach our coasts as it
dissipates through wave breaking and interaction with the seabed. Hence
the most energy profitable areas are offshore, before this interaction can take place.In
terms of wave energy extraction there are 5 options that we looked at:
- Oscillating Water Column, Overtopping, Surge, Attenuator and Point
Absorber. Examples were given of each, and Pelamis (attenuator) was
highlighted as the only commercially active Wave Energy Converter. We
also looked at several of Resolute Marine's concepts, which were all
point absorbers. Another advantage of wave energy is that it's levels
are in synch with seasonal energy demand in the US - the waves get
larger as the heating energy demand increases in the winter.Tidal
energy is only economically viable at about 20 sites around the world,
due to the need for large tidal variations combined with specific
geographical requirements. It's maximum potential contribution to the
US energy need is between 1-2%, and it is only generating power for 35%
of the day. However it's predictability means that this can be planned
for, and still utilized effectively.The development of wave energy is currently at the point as wind energy was 25 years ago. Now wind energy has converged on one design, and more and more commercial wind farms are being built. The process for wave energy should be swifter, given the lessons that have been learnt from wind. So ocean energy has a vast potential that hopefully we can start using soon.
Hosted by Professor Dick K.P. Yue
