• Question: Apparently enough sunlight reaches the Earth’s surface in one minute to satisfy the whole world’s energy demands for an entire year. how come we can't create technology to collect this energy?

    Asked by aniqamazumder to Chia-Yu, Helen, Matthew, Matt H, Rhod on 25 Jun 2013.
    • Photo: Matthew Hudson

      Matthew Hudson answered on 25 Jun 2013:

      Yes, I recently heard this as well.

      The biggest problem is capturing all that energy! Currently photo-voltaic (solar) cells are less than 10% efficient and it’s also difficult to cover the whole world with them. If we did that there would be no sun light reaching the surface of the earth and so all the plants and animals would die.

    • Photo: Helen Pritchard-Smith

      Helen Pritchard-Smith answered on 25 Jun 2013:

      30% of sunlight is reflected by the atmosphere so the remaning 70% reaches the earth and we could potentially use it. I believe the statistic was that 1 hour of light received by the earth could power the entire planet for 1 year.

      We cannot currently collect all of this energy but we are working hard to do so, in particular chemists/ chemical engineers. Trying to harness the energy so we can store it as we receive more energy from the sun than we need plus plants need sunlight too.

    • Photo: Matt Carnie

      Matt Carnie answered on 25 Jun 2013:

      The statistic I always give when I’m doing a talk is that the amount of energy received on the surface of the Earth in one day is more than humans would use in 27 years.

      We are creating technology to harvest this and I have no doubt that eventually most of our energy will come directly from the sun.

      There are many reasons why we aren’t already doing it. Firstly solar cells were only invented around 60 years ago and back then, they were only used in space as they were so expensive.

      Secondly it is impossible to convert all the energy we receive from the sun into electricity and this depends on the efficiency of the solar cell. The ones you see on peoples roofs are about 15%-18% efficient with smaller cells in laboratories being much higher.

      Thirdly. The reasons why solar energy isn’t everywhere are mainly political and economical reasons. Oil and fossil fuels are still very cheap compared to renewables. One of the biggest periods of spending on solar energy research was in the 1970s when a crisis in the middle east forced oil prices very high causing people to look for other sources of energy. Eventually we will have to rely on renewable energy more and more and as solar energy gets cheaper and cheaper, sooner or later, every roof will have solar panels meaning that more and more of the solar energy will be captured.

      The realisation that we will have to rely on solar energy is not a new concept. Thomas Edison said in 1931 “…we should be using Nature’s inexhaustible sources of energy — sun, wind and tide. … I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that.”

Comments