Energy Use of a 100-Watt Light Bulb per Year by Source

Lighting “consumes about 19% of the world’s electric power, more than all nuclear and hydroelectric plants can produce together (which is about 15% in total),” according to Grant Feller of the World Economic Forum. With significant future projected power demand and over a billion people without proper access to electricity (see Breaking Energy ‘energy poverty’ coverage here, here and here), major power generation investment will be required to liberate people from darkness and ultimately increase the untapped productivity of a swath of the population in respective developing countries. A regional UNESCO report on “energy equity and environmental security” explains further:

“Without access to a dependable and affordable supply of energy, people would struggle to meet basic and essential needs fundamental to health and wellbeing such as heating, lighting, cooking and hygiene. In addition, the operation of many essential medical devices depends crucially upon energy use, which is also needed for the refrigerated storage of food and vaccines.”

As a consequence, power grids will have to be expanded, technologically upgraded, or built up in an economically viable as well as carbon-friendly way – with future demand growth being a fundamental consideration in the process. In developed countries, it is common knowledge that switching off lights is beneficial. Turning a light off for even a short period of time will save more energy than is actually needed to turn the same light on again. Now, how much electric power is required to keep a single traditional light bulb lit for a year – 24 hours a day? The following interesting graphic shows the energy use of a 100 W light bulb per year differentiated by source:

Source: GOOD (magazine) via World Economic Forum (Twitter); click here to enlarge graphic.

Specifically, the graphic illustrates that 714 pounds of coal compared to 143 pounds of natural gas are needed to keep a single light bulb lit for a year. On the renewable side of the equation, over eight full days of sunlight hitting an area of 100 square meters covered with solar panels would be required to do the same job, while only two hours and 20 minutes of a 1.5 MW turbine spinning in the wind at 25 per cent capacity would be required. In this respect, Energy Star – a US EPA voluntary program – suggests that “if every American home replaced just one light bulb with a light bulb that’s earned the ENERGY STAR rating, we would save enough energy to light 3 million homes for a year, save about $680 million in annual energy costs, and prevent 9 billion pounds of greenhouse gas emissions per year, equivalent to those from about 800,000 cars.”

Wind power in particular appears to have advantages. From a cost perspective, wind power generation reduces the economic exposure to fossil fuel price volatility, which may justify the – in comparison to other power generation options – significantly higher upfront investment costs while operating the turbines at a lower capacity rate; i.e. operating them for a relatively low number of hours per day. Moreover, the capacity rate for offshore wind tends to be higher than for onshore wind. Therefore, in order to determine whether wind energy can be a viable option for a certain region to improve or create new access to electricity depends solely on initial costs. Fossil fuel generators, on the other hand, have limited options for optimizing cost structure. A power generator with a fleet of fossil fuel-fired plants is beholden to fuel price variability and can only limit total fuel costs by switching to cheaper fuels as markets fluctuate. Obviously, every solution has to be tailored to the specific conditions on the ground.

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