A reality check on renewables - David MacKay

Briefly: solar and wind energy requires sun or wind and tons of space relative to fossil/nuclear. Not every place has those. "A reality check on renewables" ▶ this video

What about the resources needed to build the solar and wind infrastructures ? Metal, extraction of that metal, rare earths,... ? I'm all for solar and wind and whatever, but at some point there are some maths to do... ▶ this video

No energy source [that we've discovered so far] is perfect. All have downsides. Sadly, living in denial of that fact is more popular than ever, but that's a separate topic. Here are a couple TED talks showing the downside of renewable energy - such as the enormous land usage and reliable energy storage needed to compete with nuclear or fossil. Why renewables can’t save the planet link A reality check on renewables ▶ this video

"Renewable" doesn't mean "free energy". Constructing renewable energy sources (wind, solar, etc) takes more energy than constructing an equivalent non-renewable energy source - this is the EROEI (energy returned on energy invested). There's also space limits - see ▶ this video What's apparent to me is that we live in a unique era where energy is abundant and cheap, which may never be repeated (unless fusion power is developed).

Not everywhere in the world has the land area to do wind and solar. In fact pretty much everywhere other than Russia, Australia, Canada, the US and Brazil. There the energy density per head of population is too high for renewables. Good video by the late David Mackay on that point here. ▶ this video

On that topic, I found this ted talk on the feasibility of various renewable energy sources quite eye opening ▶ this video

Well, a bunch of countries have more or less agreed on aiming for no more than 1.5 degrees warmer. IPCC made a report on what that would entail stating basically that even with an overnight abolishment it cannot be reached. But that if we assume it feasible to use afforestation and other techniques to extract CO2 from the atmosphere in the future we might have chance to reach that target for 2100 given we stop using fossil fuels by 2030. Given the scale of the transition necessary, overnight or 11-years is more or less the same time frame Edit: Great TED-talk on the scale of what’s needed ▶ this video

If you haven't read Sustainable Energy Without the Hot Air , by David Mackay, I recommend it. Free download: link About the author: David MacKay FRS is the Regius Professor of Engineering at the University of Cambridge. He studied Natural Sciences at Cambridge and then obtained his PhD in Computation and Neural Systems at the California Institute of Technology. He returned to Cambridge as a Royal Society research fellow at Darwin College. He is internationally known for his research in machine learning, information theory, and communication systems, including the invention of Dasher, a software interface that enables efficient communication in any language with any muscle. He was appointed a Lecturer in the Department of Physics at Cambridge in 1995 and was a Professor in the Department of Physics from 2003 to 2013. Since 2005, he has devoted much of his time to public teaching about energy. He is a Fellow of the Royal Society. Nine months after the publication of 'Sustainable Energy - without the hot air', David MacKay was appointed Chief Scientific Advisor to the Department of Energy and Climate Change. TED talk: ▶ this video Harvard talk: link