As governments across the world make a push towards clean energy in general and solar energy in particular, this post looks to answer the question- can solar power 100% of our energy needs.
In reality, the future will of course include nuclear, wind, hydro and biomass energy as well- but as we will see, their potential compared to solar energy is far lesser.
How much lesser you ask? A quick look at two graphs will help illustrate the point. First, we look at the potential of all renewable sources other than solar energy. The need to look at them separately from solar will become apparent in a moment.
As can be seen above, wind is the highest of these sources at 75 Tera Watts (1 TW= 10¹² Watts). Given below is the same graph with solar included:
Now we can see why solar needed a separate graph- fitting it on the same graph as other sources will need a screen 60 feet in size! To see how we arrive at the 26000 TW number, refer to this post.
So we now know solar energy is abundant and larger than any other source available to us- but is it large enough to power all our needs?
To answer this question, it would help to know that this 26000 TW that we receive from the sun is spread roughly at 1000 W/m² on the Earth’s surface.
To capture this energy and convert it into electricity we would need a large array of solar cells. Assuming a solar cell efficiency of 20% (the best solar cells today have an efficiency around 21%), we will be able to capture 200 W of this energy with a solar panel 1 m² in size.
Assuming 250 days in a year have enough sunlight to produce electricity for 8 hours, each solar cell can produce about 400 KWh every year. For reference, an average US household uses this much energy.
The US Energy Information Administration (EIA) estimates that total energy consumption of Earth is projected to reach 199721 TWh by 2030.
Thus the area needed to power our energy needs in 2030 can be easily calculated as follows
Area needed= 199721*10¹²/(400*10³)=496805 Sq. KM
While that is a large area on an absolute scale, relatively speaking it is just about .33% of Earth’s land area- in other words, we receive enough solar energy to power 300 Earths! The Sahara desert alone at 9.4 million sq KM is about 18 times the size of the area we need. In reality, the solar panels will of course be spread geographically to meet local demand. The map below helps give a visual estimate of how much area this would need across continents.
Not all that large an area, is it? No wonder solar panels are the ubiquitous face of the renewable energy revolution. While we also need to solve the problem of energy storage before this map represents on-ground reality, that is a matter of when and not if.
Seen this way, a clean energy future is not only achievable but inevitable. But with climate change worsening every passing day, the real question for us to answer is not one of viability but this-can we muster the individual, societal and political will to get there in time?