A sense of units and scale for electrical energy production and consumption

Discussions about energy and electricity can be confusing. Often, the root of this confusion lies in the choice of units and scale. Firstly, units are often quoted inconsistently: we switch between watt-hours, kilograms of oil equivalent, joules, and even more confusingly, units of power. Secondly, we begin quoting big numbers in the order of millions and billions without a sense of scale: is the unit equivalent to one, ten, or one hundred coal-fired power stations? Thirdly, we lose perspective on the equivalence between electrical energy production and consumption: how many people could a wind or solar farm provide for?

To make our full data entry on Energy Production & Changing Energy Sources as useful and clear as possible, we have standardized all of our energy data into a single energy unit: the watt-hour (Wh). The only variation on the watt-hour which we have used is in scaling large numbers into kilowatt, megawatt or gigawatt-hours (which are one thousand, million, and billion watt-hours, respectively). The base unit of the watt-hour, however, remains consistent. This should help to reduce confusion for the first of the three reasons described above.

To address the latter two challenges we have produced the chart shown below, which aims to provide a sense of scale for both electricity production and consumption [clicking on this chart offers a pop-out version, for which some finer aspects can be more easily read]. It is comprised of two scales: electricity production and electricity consumption. On the left-hand side we have a chart which extends from zero up to 100,000 MWh. The individual arrows represent the daily electrical outputs of different plant types; as we see, there is a large range of outputs depending on the size and conditions of the specific facility. The average daily output of specific power plants (some of which you may recognize) are shown and labelled as individual stars.

The labeled horizontal lines on these charts aim to give a sense of perspective on electricity consumption levels across the world. For example, in the chart below a very large hydro or nuclear plant could produce enough electricity to meet the demands of 100 million people in Ghana; a large hydro, nuclear, or coal plant could provide for 10 million average global citizens, and average-sized plant would meet demands of ten million in Brazil.

The left-hand chart is dominated by hydropower, nuclear, coal and geothermal production. The output of onshore and offshore wind, and solar photovoltaic (PV) farms currently lie below 10,000 MWh per day, which you see at the bottom of the left-hand chart. The right-hand chart provides a magnification of the bottom section of this chart, extending only from zero to 10,000 MWh. Just as in the left-hand chart, the range of daily electricity outputs from wind and solar PV farms are shown by the arrows, with specific farms represented by stars. Again, we have provided a sense of perspective on how this relates to electricity consumption needs across a range of countries using the labeled horizontal lines.

The data used in these charts are not perfect; we have attempted to provide a global-level overview of a range of electrical energy production sources and average levels of consumption across countries. These figures are based on a number of assumptions and calculations which are explained in detail below. Despite these limitations, we hope these charts are of value in providing an overall sense of scale for both production and consumption.

Energy units 01

Data sources for electrical energy production and consumption chart