Curious facts about electricity supply

Distributing electricity


How do you generate electricity from waves?  Tidal energy devices use the natural rise and fall of coastal tidal waters caused principally by the interaction of the gravitational fields of the Sun and Moon. The tide moves a huge amount of water twice each day which can be harnessed to drive turbines which power generators to produce electricity.  Although tidal energy is plentiful, a major drawback is that it can only be generated when the tide is flowing in or out, which only happens for approximately ten hours each day.
As pressure to find sustainable, ‘clean’ methods of energy production mounts, engineers are seeking to harness the power of waves. Waves are more predictable than the wind and hold a huge store of untapped energy. Scottish company Pelamis Wave Power is among those tapping into that energy. Three of its 750kW wave-power machines were part of the world’s first commercial ‘wave farm’, which opened off the coast of Portugal in 2008. That project is now closed, but Pelamis’s P2 was recently named as one of the machines that will be used at three of the six UK offshore sites. The machines will be located 5-10km offshore, where the water is 50-150m deep. Each machine is made up of a series of cylindrical sections, up to 38m long and 4m in diameter, linked by hinged joints. It is ‘slack moored’ so it can swing freely, naturally aligning itself at right-angles to oncoming wave fronts. The UK has about 1000km of Atlantic coastline. The average potential energy of Atlantic waves is 40kW per day for every metre of coastline, which is enough to power around 20 domestic kettles. So, scaling up, 65 P2 machines could generate almost 50MW of power – enough to power up to 33,000 homes a year.

How do we move electricity?
Once electricity is made at power stations, it needs to get to our homes, schools and hospitals – but how?

Tall pylons carry power lines from the power stations to sub-stations near where we live.  From there, cables buried underground carry this electricity to our homes and schools.

What happens to unused electricity?
Electricity-pylonsAs it’s not possible to store large amounts of electricity, every minute of the day electrical technicians perform an elaborate balancing act between supply and demand.

They monitor what we are doing at home or school or work, and when they notice that we are all switching on a kettle, say at the end of a football match, they switch on additional supply.

Some sources of power provide a speedy response, like releasing more water into a hydroelectric power plant or cranking up the power in a gas-fired power station.

Other sources, like nuclear, are slower to turn up or down.

However, sometimes things do go wrong.  When one or more power stations don’t quite get the balancing act right, this causes a power cut, like the ones the country saw in May 2008.

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