Energy is the thing that keeps the world moving. Meanwhile, our dependency on non-renewable sources of energy like petroleum is likely to lead us to the crisis. We do have the option to shift to clean energy sources. But, can these clean energy sources, solar energy to be in particular, replace petroleum?

Solar Energy
Photo by American Public Power Association on Unsplash

World energy demand and dependence

Development is accelerating and the world is moving forward. In 2018, 80 Gigajoules of primary energy was consumed within a year per person taking into account that 600 Exajoules (1 Exajoule = 10^18 joule) of primary energy was consumed in 2018. This energy distribution is more on developed countries and is less on developing and underdeveloped countries.

Among the total energy demand of the world, almost 86% of energy demand is sufficed by non-renewable sources of energy like coal, oil, natural gas, and nuclear energy. Petroleum dependence of the world is solely 32%. This shows that we are completely dependent upon fossil fuels which are non-renewable rather than clean and renewable source of energy.

The dependence of the world in such a non-renewable source of energy has a severe drawback, it is the main reason for global warming. Growing environmental concerns forbid us to depend on such sources of energy, it can jeopardize the future of humanity. So, the shift of energy dependence to solar, wind and hydro energy is a necessity.

Solar Power and its Promise

Sun is the major source of energy on Earth. It is also called the ultimate source of energy. Although solar energy dependence is much lower than hydro energy right now in the world, it does show a lot of promise. Total solar energy absorbed by Earth surface is nearly 122 Petawatts. This is nearly equal to 3.85 million exajoules of energy and is 4 orders greater than the total primary energy consumption of the world.

Solar energy seems to be more than sufficient for the world numerically. If only we could harvest 0.1 percent of the total energy absorbed by the Earth’s surface, we won’t be needing any other energy sources at all. But, it is not possible as there are ample complications when it comes to harvesting solar energy.

Hurdles in the Rise of Solar Energy

Solar energy is ubiquitous. We can extract it anywhere but not anytime. There are limitations of solar power which makes it less preferable than others. We can only get a good amount of solar energy during some hours of day time. Also, the cloud can obscure the sun hence decreasing the energy yield.

Apart from its limited availability, solar energy harvesting with maximum efficiency is itself a problem. The solar cells and thermal collectors are major devices used for solar energy harvesting.

Solar cells are mostly used among these two and it is very less efficient. And, these energy harvesting devices require a very large area for harvesting a large volume of energy. The efficiency enhancement of these cells is under research because efficiency over 50% in solar power can easily make solar-powered devices thrive and make them more preferable over other devices.

Development of Solar Energy Harvesting Technology

Solar energy harvesting has become very cheap with the development of silicon solar cells but still, they are less efficient. The maximum theoretical efficiency of these solar cells is around 30%. Practically, this value is even lesser. But, still, they are a reliable source of energy in many places. Further, they are clean energy sources, aiding the environment as well. These factors attract researchers and encourage them for its further development.

There has been ample amount of research for improvement of solar cells till date. Unlike single-junction silicon solar cells used at present, using multi-junction solar cells, efficiency has been improved to a maximum value of close to 50%. But, the commercial ones are of course less efficient than the prototypes.

Moreover, using different materials like Cadmium Telluride, Copper indium gallium selenide and different silicon tandem efficiency of silicon solar cells have been enhanced. Maybe in future, we can power a whole house with solar cells of size as small as 2*2 foot square.

Can Solar energy replace petroleum?

Replacing petroleum is necessary but not even hydroelectricity, one of the most consumed renewable sources of energy has the ability to replace petroleum completely. Solar energy does show some ability since as stated above only changing 0.1 percent of solar energy absorbed by the surface of Earth can fulfill our energy demand. But, it is theoretical. We cannot cover completely all the available land by solar cells, can we?

Despite hurdles in harvesting solar energy, we can definitely replace petroleum with solar power but for this, we require highly efficient solar cells. With modern solar cells, we have to cover 10 percent of Earth’s surface by solar cells to power humanity. That is not feasible but we can develop roofs powered with highly efficient solar cells so that we can fully absorb the solar energy incident upon human construction covered area of Earth.

To overpower petroleum we must be able to manufacture solar cells that can collect solar energy efficiently in the low light of dusk and dawn. Also, energy harvesting devices like batteries should gain significant improvement. And finally, we can slowly replace petroleum-powered industries and vehicles to solar-powered ones.

Ashwin Khadka is a PhD Scholar in Nano Energy and Thermofluid Lab in Korea University, Republic of Korea under Korean Government Scholarship Program. He has a Masters Degree in Physics from Tribhuvan University, Kathmandu, Nepal. He is a science enthusiast, researcher and writer.