The world consumed energy at the average rate of 10^13 W in 2011 (the figure is probably increasing at a global average of 10% a year). This like keeping 100 billion 100-Watt bulbs switched on at the same time.
I am not sure how much of this energy consumption is in the form of electricity. We do consume a lot of energy in other forms, such as food, or gas, and I am assuming this wikipedia estimate takes everything into account.
A quick calculation shows that the earth receives about 10^17 Watt of energy from the sun on an average. Of course how much reaches the ground depends on local factors, like if there's a lot of cloud cover there would be a lot less solar radiation reaching the earth. But the amount of energy reaching the outer layers of the earth's atmosphere is fairly constant, because the Sun has been burning brightly at about the same level of brightness for many million years now, and is expected to do so for quite a while now. This so-called "solar constant" is the power reaching a unit surface area of the earth's atmosphere, and is estimated to be about 1400 W/m^2. Multiply that by the earth's surface area which is about 10^14 m^2, and we get the above quoted figure of 10^17 W.
Of course a large percent is absorbed by the atmosphere, but if we built solar panels to cover 1% of the earth's surface area (that's a lot but let's suppose we can do it by covering every house rooftop, several deserts, and even have some floating on the ocean whose energy can be channeled offshore using underwater cables.) , and extracted energy from it with a humble efficiency of 1%, we would still have 10^13 W of power production. This is equal to the planet's total energy consumption! We could reduce that by a factor of half given that the solar panels are not working at night time, but we still have a lot more energy than is consumed as electricity.
There is no reason then not to invest in solar energy technology. The Sun is here to stay in the foreseeable future of the human race. The efficiency of light-to-electricity conversion can only get better. So will the other technological aspects such as energy storage and transport. Even as we speak, many research groups around the world are developing better photodiodes (that efficiently convert light to electricity) and better batteries (to store this energy). All things taken together, the costs will come down, and the rates of production will increase. This is what countries in the European Union, such as Denmark or Germany have been doing....investing in clean, renewable and non-hazardous sources of energy. The US, the usual suspect, lags behind on this front. I live in the "Sunshine state" of Florida and have rarely seen houses fitted with solar panels, much less people talk about it. The vibes I get from the media are also negative. Obama was heavily criticized for investing in a solar company that failed (the weird laws of market economics always find a way to stand in the common-sensical laws of physics).
These estimates are all some amateurish off-the-top-of-head quick and dirty estimates, the product of one morning's "research" on wiki. So i might have missed a lot of important points or nuances, but you can't argue with these numbers. I wish I lived and worked in a place where people talked more about these things, so that some of it rubbed off on me. One of the strengths of people with an education in the physical and mathematical sciences is that we can make these estimates and play with numbers to get a good big picture in most things - be it energy, biology or economics. I am itching to flex that muscle on such matters of social import, rather than just some esoteric stuff (which is what I currently do and somewhat enjoy). Maybe I will go to such a place next.
I am not sure how much of this energy consumption is in the form of electricity. We do consume a lot of energy in other forms, such as food, or gas, and I am assuming this wikipedia estimate takes everything into account.
A quick calculation shows that the earth receives about 10^17 Watt of energy from the sun on an average. Of course how much reaches the ground depends on local factors, like if there's a lot of cloud cover there would be a lot less solar radiation reaching the earth. But the amount of energy reaching the outer layers of the earth's atmosphere is fairly constant, because the Sun has been burning brightly at about the same level of brightness for many million years now, and is expected to do so for quite a while now. This so-called "solar constant" is the power reaching a unit surface area of the earth's atmosphere, and is estimated to be about 1400 W/m^2. Multiply that by the earth's surface area which is about 10^14 m^2, and we get the above quoted figure of 10^17 W.
Of course a large percent is absorbed by the atmosphere, but if we built solar panels to cover 1% of the earth's surface area (that's a lot but let's suppose we can do it by covering every house rooftop, several deserts, and even have some floating on the ocean whose energy can be channeled offshore using underwater cables.) , and extracted energy from it with a humble efficiency of 1%, we would still have 10^13 W of power production. This is equal to the planet's total energy consumption! We could reduce that by a factor of half given that the solar panels are not working at night time, but we still have a lot more energy than is consumed as electricity.
There is no reason then not to invest in solar energy technology. The Sun is here to stay in the foreseeable future of the human race. The efficiency of light-to-electricity conversion can only get better. So will the other technological aspects such as energy storage and transport. Even as we speak, many research groups around the world are developing better photodiodes (that efficiently convert light to electricity) and better batteries (to store this energy). All things taken together, the costs will come down, and the rates of production will increase. This is what countries in the European Union, such as Denmark or Germany have been doing....investing in clean, renewable and non-hazardous sources of energy. The US, the usual suspect, lags behind on this front. I live in the "Sunshine state" of Florida and have rarely seen houses fitted with solar panels, much less people talk about it. The vibes I get from the media are also negative. Obama was heavily criticized for investing in a solar company that failed (the weird laws of market economics always find a way to stand in the common-sensical laws of physics).
These estimates are all some amateurish off-the-top-of-head quick and dirty estimates, the product of one morning's "research" on wiki. So i might have missed a lot of important points or nuances, but you can't argue with these numbers. I wish I lived and worked in a place where people talked more about these things, so that some of it rubbed off on me. One of the strengths of people with an education in the physical and mathematical sciences is that we can make these estimates and play with numbers to get a good big picture in most things - be it energy, biology or economics. I am itching to flex that muscle on such matters of social import, rather than just some esoteric stuff (which is what I currently do and somewhat enjoy). Maybe I will go to such a place next.
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In England, where rain/cloud-free days were really rare, it was ironic to hear a lot of researchers around me talking about (and working on) solar energy :) We are blessed with so much sunshine in India, and yet, it is exploited so little! Not that different from the US I'd say.
I was glad to hear that the newer multistoried buildings in Mumbai are required to have solar panels on the rooftop (and harvest rainwater). I also heard about a long term plan to cover most of the rooftops in IITB (academic + residential) with solar panels. Hopefully, things are changing...
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