Not a day goes without opening up newer ways of looking at things. The same holds true for CO2 emissions and climate change concepts. Take for example, the curious case of cement, which, all these days, was known to be an undisputed climate villain, being the emitter of 4 to 5% of global carbon dioxide output. Then came the revelation that since concrete, and not cement is the end product or material of construction, the carbon footprint of concrete, needs to be compared with competing construction materials such as steel, aluminium, glass or wood, and apparently concrete compares quite favourably in that gallery of rougues. Next came, the theory of accounting for both direct and indirect CO2 impacts, which made us add up all the carbon emissions in auxiliary activities such as packaging, transportation, etc.
And then came the concept of total lifecycle costs of a product for wholesome comparisons, which extended to lifecycle carbon emissions of materials like cement, encompassing CO2 generated during manufacturing, transportation, storage, packaging, application/construction and finally through its long life as concrete in buildings. Surprise of surprises, this analysis threw up a hitherto unknown revelation that concrete works as a sink for atmospheric CO2, and according to a Chinese study, concrete has the potential to absorb upto 40% of the CO2 generated in cement production of comparable quantity. So, old ideas can be made to stand on their head as our analyses become more and more refined.
Just as a traditional climate villain like cement has now been shown to be somewhat more sustainable than we thought, our climate hero, solar power is probably taking a bit of an opposite journey, and here too, the concept of carbon mapping through the life cycle of the product has shown the way. Solar panels have to be made by melting silicon at a high temperature of 1,414 degrees centigrade, which requires energy, and this in turn emits CO2! This is being referred to as 'Carbon Debt' of solar panels as they start generating green power.
A study conducted by Utrecht University and reported in the Economist magazine/Nature Communications, has come up with estimated numbers for what we may call 'Carbon Pay-back' in number of years, (the number of years required by a solar panel to generate energy equivalent to what was consumed in manufacturing the same panel) which also has been improving continuously as the process of making solar panels kept on becoming more and more energy efficient. In 1975, this carbon payback would be about 20 years, while for solar panels manufactured today this payback period has climbed down significantly to just two years of solar power generation. Optimistically speaking, global solar break-even might have come as early as 1997, and pessimistically, we may see this happen only in 2018. Be that as it may, post 2018, we can in any case wholeheartedly announce that solar power has no more any blemishes - even on lifecycle basis.
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