When it comes to Ireland’s electricity market, there’s a lot of talk of renewables, but it might be worth taking a step back to begin this discussion. Ireland is a small country that imports a lot of goods and materials and one commodity which we also import is electricity, the same commodity which features in all our homes and workplaces.
Electricity is the flow of electrons through a conductor. What does this mean? The most common analogy used is water flowing through a pipe. The pressure in the system (which causes the water to flow) is the voltage, the actual flow of water is the current. Increasing the pressure is only useful if the pipes can still carry the water around the system effectively.
Now we can see what voltage and current are, but the units of energy are not given in terms of voltage or current. Power and energy are reported in watts (W/kW/MW/GW) and watt-hours (Wh/kWh/MWh). Power is the ability to do work. Energy is the capacity to do this work. The units are to do with the instantaneous rating, and the sum of these efforts.
Put on the kettle
You probably want a cup of tea right about now so put on the kettle and the rating of your kettle will help to illustrate this point. Say, your kettle is rated at 1.5 kW, that’s 1500 watts (k is kilo) and this is the power required to turn the device on. A typical kettle takes around five minutes to boil so this power rating is required for five minutes to boil the water.
If you continuously boiled it (assuming it still takes five minutes each time), you could boil it a dozen times in one hour using 1500 watt-hours of energy, 1500 W of power for one hour. If you boil it just once in an hour then you have used one twelfth of this i.e. 1500 Wh/12 = 125 Wh of electricity. The typical usage for a household in Ireland is around 4,200 kWh per year which would be the equivalent of boiling the kettle more than 90 times every day!