I am always a little twitchy when I hear of the next latest invention based around renewable energy – whether it be solar panels or (self-driving) electric cars  - as far as saving the planet and reducing the carbon footprint.


Dear Colleagues

EIT Stock ImageI am always a little twitchy when I hear of the next latest invention based around renewable energy – whether it be solar panels or (self-driving) electric cars  - as far as saving the planet and reducing the carbon footprint.

As we all know, the actual operation of solar panels in generating clean energy is without question a renewable resource. No carbon dioxide poured out. However, the question which always puzzles me is whether the heat and energy required to make the solar panel (and all its associated components such as inverters, storage batteries, cabling, control  and switchgear) creates more carbon dioxide than is saved in using the solar panel.

Good Research confirming a Good Net Effect of Solar Panels
A recent paper reported in the Economist from Wilfried van Sark of Utrecht University has done a great job in calculating what is happening on a global macro scale with solar panels. And the news is good.

The researchers calculated the total amount of energy to make all the solar panels installed around the world from 1975 to 2015 and the resultant carbon emissions. They then worked out the total amount of energy that these panels have produced since their installation. They found the break even occurred in 1997 when the clean energy produced by solar panels outstrips the carbon dioxide required to produce them (the solar panels). Solid research and convincing evidence.Great to see.

The Numbers are Interesting
Seemingly, 20 grams of carbon dioxide are produced per kWh of energy for a solar panels. On the other hand - the Energy Information Agency reckons it is about 550 to 940 g of carbon dioxide per kWh for conventional coal, oil or gas generation.

So 20 g for solar panels is outstandingly low in comparison. Today the amount of carbon dioxide associated energy used in creating a solar panel has dramatically fallen to about 5% of what it  was in 1975. A significant reduction.

And naturally every solar panel installed goes some way to reducing the Carbon Dioxide emissions associated with producing the next one.

Other interesting numbers tossed around are that the sun’s energy can typically be 1kW/square meter. With a panel’s efficiency of 20%, this means 200 Watts are produced per square meter.

The End Game
Naturally, once the cost per kWh gets close to that of fossil fuels, the take-up of solar power will ramp up dramatically. In remote locations, one could safely argue that the cost of solar power is close to that of fossil fuels (or indeed lower).

A good quotation from the Buddha:  Three things cannot be long hidden: the sun, the moon, and the truth.

Yours in engineering learning

Steve

Mackay’s Musings – 22nd Nov’16 #627
780, 293 readers – www.idc-online.com/blogs/stevemackay

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