Saral writes: “Many experts who tried to measure it expressed doubt that the EROEI [Energy Return on Energy Invested] of solar energy technology is positive.”
Who are these experts? The claim was only true several decades ago, before solar PV modules were mass-produced. But nowadays numerous studies, using Life-Cycle Assessment, show that solar PV typically generates its energy inputs (including mining and manufacturing) within 1–3 years, depending upon site; for large wind turbines it’s 3–9 months. For comparison, the operating lifetimes of these technologies are typically around 25 years.
Of the few studies obtain much longer energy payback periods, most include absurdly large amounts of “back-up”, so that the main energy inputs come from this “back-up”, not renewable energy.
As energy technologies are made increasingly by using renewable energy, energy inputs become of minor importance compared with carbon inputs.
I agree with part of the following additional point that Saral makes, namely that “Miners must then go to ever remoter and ever more difficult places to extract them [raw materials and energy] out of new mines/wells.” This is indeed a strong limitation on the continued production of fossil fuels, but is irrelevant to renewable energy resources: sunshine, wind, etc.
However, it is relevant to the raw minerals mined in order to make renewable energy technologies. This is a much less urgent problem than the fuel problem, which renewable energy solves. Nevertheless, it must be addressed, while recognising that the problem applies to all products made with non-renewable materials, not just renewable energy technologies. Clearly some major socio-economic and cultural changes are needed in order to embed the principle of “reduce, reuse and recycle” into the economic system.