The most important metrics in energy data are gigawatt (GW) and gigawatt-hour (GWh).
- Gigawatt (GW) is a measure of instantaneous power. Smaller units are watt (W), kilowatt (kW), and megawatt (MW).
- Gigawatt-hour (GWh) is a measure of energy used or generated over time. Smaller units are watt-hour (Wh), kilowatt-hour (kWh) and megawatt-hour (MWh).
Together, power and energy tell us the capacity of electricity systems and their ability to meet demand.
A 1 GW power plant can produce 1 GW of power at any point in time.
If that power plant runs at full capacity for 1 hour, it produces 1 GWh of energy in that time.
Gigawatts (GW) in the Real World
Here is the capacity of Australia's biggest power generators for each technology:
- Biggest hydroelectric power station (Tumut 3, NSW): 3 GW (3000 MW)
- Biggest coal power plant (Eraring, NSW): 2.9 GW (2880 MW)
- Biggest wind farm (MacIntyre, QLD): 0.9 GW (923 MW)
- Biggest solar farm (New England, NSW): 0.5GW (470 MW)
(Data via Open Electricity)
Gigawatt-hours (GWh) in the Real World
In Australia, 1 GWh of energy can power roughly:
- 1.33 million homes for 1 hour
- 56,000 homes for 1 day
- 8,000 homes for 1 week
- 1,800 homes for 1 month
- 150 homes for 1 year
(Based on the average Australian household consuming about 6,500 kWh per year, which is 0.0065 GWh.)
Useful comparison: Speed and Distance
To help us understand the difference between power and energy, a useful comparison is speed and distance.
Power is like Speed.
- Think of power like speed. If a car can drive 200 km/h, we know at any given moment it can reach 200 km/h.
- Power is the rate at which energy is generated or consumed at any given moment. It is an instantaneous measurement.
Energy is like Distance.
- Think of energy like distance travelled. If a car drives at 100 km/h for 3 hours, it travels 300 km.
- Energy is the total amount of power used or produced over a period of time. It is the accumulation of power delivery over hours, days, or years.