Energy Basics

Where does our energy come from?

In physics, energy is the quantitative property that is transferred to a body or to a physical system, recognisable in the performance of work and in the form of heat and light. In simple terms, energy is the ability to do work. It is what makes things move, heat up, light up, and so on. There are many different forms of energy, including:

• Kinetic energy: The energy of motion. A moving object has kinetic energy.

• Potential energy: The energy of position. An object that is held up in the air has potential energy.

• Heat energy: The energy of random motion of molecules. A hot object has heat energy.

• Light energy: The energy of electromagnetic waves. A light bulb emits light energy.

• Electrical energy: The energy of moving electrons. A battery stores electrical energy.

• Chemical energy: The energy stored in the bonds of atoms and molecules. Food contains chemical energy.

• Nuclear energy: The energy released from the nucleus of an atom. Nuclear power plants use nuclear energy to generate electricity.

Energy can be converted from one form to another. For example, the chemical energy in food is converted into kinetic energy when we eat it and move around. The kinetic energy of a moving car can be converted into electrical energy when the car's brakes are applied. The heat energy from the sun can be converted into electrical energy using solar panels.

All the energy we produce or use can be traced back to the sun either directly when we use solar energy or indirectly: We absorb solar energy in the form of food (plants need the sun to grow, animals need plants to thrive, and so on) or use it in the form of oil, petrol, gas and wind (all fossil fuels are the remains of living things, wind wouldn't exist without the warmth of the sun).

Ireland's Energy Future

Currently Ireland relies heavily on imported fossil fuels to generate energy. The move to renewables - wind and solar - will not only reduce CO2 emissions but will also make Ireland less dependent on imports and in the long run bring down energy prices.

The goal stated in Ireland’s Climate Action Plan 2023 is to generate a total of 9 Gigawatts (GW) onshore and 7 GW offshore wind energy capacity respectively, with solar providing another 8 GW. This could make Ireland - almost - energy independent.

The big disadvantage of renewables is that energy is only created when the sun shines and the wind blows. Fossil fuels on the other hand can be used at any time to create energy. Solutions to this problem are currently being developed and include the storage of energy and the production of hydrogen from excess wind energy which can be used as a clean alternative energy source in times when wind and solar don’t cover the energy demand. Fossil fuels, mainly gas, will however keep playing a role as a backup into the future.

Some useful Energy Terminology

• Voltage:

Voltage is measured in volts and comparable to water pressure. The electricity in your wall sockets is at a voltage or ‘pressure’ of 230 volts. A smoke alarm battery gives out electricity at only 9 volts. To use the water comparison this is the difference between water coming out of a garden hose or a water pistol.

• Current:

Current is measured in amps and describes the amount of electricity that can flow. Going back to the water comparison this is determined by the size of the hose, more water can flow through a fire engine hose than a garden hose. Similarly, more electricity can flow through a standard socket at a rate of up to 13 amps, but the fuse in the plug might only allow 5 amps to flow through to the appliance.

Some useful Lighting Terminology

• Kelvin:

The light you get from modern bulbs varies not only in brightness but also in “colour temperature” which is measured in Kelvin. This ranges from 2,700 Kelvin (yellowish end of the spectrum, warm, relaxing) to 4,000 Kelvin (bluish end of the spectrum, crisp and energising).

• Lumen:

This tells you how bright the light from any particular bulb will be. How many lumens you need depends on whether it is for ambient, accent or task lighting.