Due to technological advances, fossil fuel reserves have been growing in recent years. But to stop climate change from progressing, we need to leave the majority (70%) of these fossil fuels in the ground. How many solar panels are needed to replace the energy from these fossil fuels?

According to The Guardian, fossil fuel reserves have recently been increasing due to better technology. At the moment, there are about the following reserves of fossil fuels, expressed in CO2 (see graph):

Coal: 2200 Billion tonnes of CO2
Oil: 600 Billion tonnes of CO2
Gas: 400 Billion tonnes of CO2

Oil companies are keen to use all of these valuable reserves, but in order to limit Climate Change to 2 degrees we have to leave 70% of this CO2 in the ground. So how many solar panels are needed to stop Climate Change? The answer lies in the ‘carbon intensity‘ of the different fuels, which is the amount of carbon emitted to produce one kWh of electricity. Roughly these carbon intensities are as follows:

Carbon intensity of generating electricity by fuel type:

Coal: 1.0 kilogram of CO2 per kWh
Oil: 0.9 kilogram of CO2 per kWh
Gas: 0.6 kilogram of CO2 per kWh
Solar PV: 0.1 kilogram of CO2 per kWh

Hence solar panels save 0.9 tonne (1000 kilogram) of CO2 per MWh (1000 kWh) versus coal, and 0.8 and 0.5 kilogram CO2 versus Oil and Gas. So how much MWh generated by solar panels is needed to leave 70% of these fossil fuels in the ground?

Coal: Leave 0.7 * 2200 = 1540 Billion tonnes of CO2 in the ground
which requires 1540 / 0.9 = 1710 Billion MWh of Solar
Oil: Leave 0.7 * 600 = 420 Billion tonnes of CO2 in the ground
which requires 420 / 0.8 = 525 Billion MWh of Solar
Gas: Leave 0.7 * 400 = 280 Billion tonnes of CO2 in the ground
which requires 280 / 0.5 = 560 Billion MWh of Solar

Hence in total we need 1710 + 525 + 560 = 2800 Billion MWh of Solar. A residential solar panel system of 4kWp (16 panels) in the UK will generate about 100 MWh over it’s 25 year lifetime. Hence we require 2.800 Billion / 100 = 2.8 billion Solar Panel installations. But since we have about 100 years to limit the CO2 and the solar panel lifetime is 25 years, we can divide the required systems by 4. Hence we require 2.8 Billion / 4 = 700 million solar panel installations.

700 Million solar panel installations of 4kWp (16 panels) would be enough to stop Climate Change. At the moment there is about 100 GWp of solar installed, which equal 25 Million solar panel installations – so we only need 30 times more solar panels, which is totally achievable!