Tidal Power

My New Scientist Magazine did not arrive on Friday. What to do for bedtime reading I thought? Perhaps an old copy? Well I did find an old copy under the bed, and it had some interesting stuff in it about tidal energy.

Recently there has been talk of the Severn Estuary project being looked at again. Part of the problem with this could be environmental.
The bit in the New Scientist talked about the strong tides around the Orkney Islands, which has led the European Union-funded European Marine Energy Centre (EMEC) to use Orkneys' waters as the world's largest test bed for a renewable energy source. The new turbine designs being tested here appear to be surviving the Scottish swells, and should be capable of taming one of the world's most promising sources of renewable energy. If we can use this technology to harness the powerhouses of Ocean currents, tidal power could help smash all previous predictions of how much energy the oceans can provide.The power can be environmentally friendly as well.

Neil Kermode, who manages EMEC says tidal turbines have taken the lead in the race to develop marine energy sources, surging past both barrages and wave power.

Back in May, an article in the IET E&T magazine recons that the growing marine sector in the UK could boost the economy by up to £76bn by 2050 and also generate over 68,000 jobs, if the country builds on its existing lead and successfully develops and deploys its technology.

- http://www.reuk.co.uk/Lunar-Energy-Tidal-Power.htm
- http://www.power-eng.com/news/2011/12/1558510906/renewables-rolls-royce-moves-into-the-fast-sea-lane.html


As well as tidal power looking good, wave power is also on the agenda. Anaconda says that wave energy is a particularly rich yet untapped energy resource which government studies state could produce 3%-5% of our electricity initially and up to 20% eventually. more in the August edition of NS.

The Crown Estate owns the majority of the seabed within a 12 nautical mile limit of UK territorial waters.
The estate has already made available areas for the development of offshore tidal power projects.
The Crown Estate, which manages the monarch's property holdings, already has properties that generate 1.55 gigawatts of offshore wind projects in Wales, Scotland and England.
It has recently launched offshore wind and tidal stream leasing rounds to select developers to take forward up to 800MW of projects in Northern Ireland waters.

Renewable Energy or a Perpetual Motion Machine?

Axel Kleidon of the Max Planck Institute has concluded that it is a mistake to assume that energy sources like wind and waves are truly renewable.
His analysis says that if you build enough wind farms to replace fossil fuels, we could seriously deplete the energy available in the atmosphere, with consequences as dire as severe climate change.

It appears that the idea that we can harvest unlimited amounts of renewable energy from our environment is as much of a fantasy as a perpetual motion machine.

Humans currently use energy at the rate of 47 terawatts. Axel calculates that this is roughly 5 to 10 per cent of the “free” energy available. About 17 TW comes from burning fossil fuels. So to replace this, we would need to build enough sustainable energy installations to generate at least 17 TW, but because no technology can ever be perfectly efficient, some of the free energy harnessed by wind and wave generators will be lost as heat.

Axel says "Large-scale exploitation of wind energy will inevitably leave an imprint in the atmosphere." "Because we use so much free energy, and more every year, we'll deplete the reservoir of energy." He says this would probably show up first in wind farms themselves, where the gains expected from massive facilities just won't pan out as the energy of the Earth system is depleted.

Axel says that we are going to need to think about fundamental principles much more clearly than we have in the past. He says "We have a hard time convincing engineers working on wind power that the ultimate limitation isn't how efficient an engine or wind farm is, but how much useful energy nature can generate."

The answer may lie in direct solar energy, but to be sustainable, it will probably have to be based on cheaper and more readily available materials such as zinc and copper. Unfortunately many of the most efficient of today's thin-film solar cells require rare elements such as indium and tellurium, whose global supplies could be depleted within decades. The trouble is that current systems convert only a small fraction of the light that hits them to power, and absorb most of the rest, passing heat into the environment.

New Scientist - Wind and wave farms could affect Earth's energy balance

As with everything there must be a balance somewhere. But this type of article does make one stop and think.