Friday, April 02, 2010

Energy Sustainability

I spent an entertaining hour this afternoon listening to David MacKay of Cambridge (UK) give a talk about the Future of Energy here at Harvard.  I've mentioned David in this blog before.  He did a lot of early work on low density parity check codes and deletion codes, so we've run in the same circles for quite some time.  But now, besides his well-known book on information theory (Amazon link, free downloadable version), he's written a book on sustainable energy (Sustainable Energy - Without the Hot Air : Amazon Link, free downloadable version) that was the subject of his talk.  David's also recently been named Chief Scientific Advisor to the Department of Energy and Climate Change (UK). 

The talk was based on the book.  David's starting point is the question, "What would we have to do to move to a world where we weren't using fossil fuels?"  (The "we" he's talking about is usually the UK, but it applies elsewhere as well.)  He then takes a truly scientific approach.  He considers various possible renewable energy sources (wind, solar, biomass, tides), and estimates things like their energy output per unit area.   Based on these calculations, he figures out how much land would be required.  So, for instance, if you were willing to cover 1/2 of Britain with windmills, things might look OK, but that's not a very likely possibility.  He also considers the demand side of the equation, and what might feasibly be done there.

The book (and the talk) are not overtly political.  Whether you believe in global warming or not, the question of sustainable energy is important -- for national security concerns, you might not want to be dependent on getting your energy from, for example, oil-rich countries.  His book is not about the politics;  rather, he tackles these questions as a scientist, producing the numbers that are needed for intelligent, reasoned discussion and debate on the issues.  That might sound dry and, possibly, boring, but not in David's hands.  He's blessed with a fine wit and a charming style that comes out in the book and even more so when he's speaking.  (His slide showing a collage of posters from places protesting the introduction of windmills into their community, for instance, received a lot of laughs.) 

David has done a truly rare thing as a scientist, writing a book firmly about the science of an issue of current import that people are actually reading and that is raising the level of debate.  I admire his courage in taking on a challenging assignment, and hope his work helps lead to the positive changes he is looking for.    


Anonymous said...

Even Bill Gates seems to be a fan - he tipped his hat to MacKay in his recent TED talk.

Why is climate change something to believe in? Isn't it incontrovertible science?

Unknown said...

Hopefully the talk didn't begin, "Assume the existence of unlimited, efficient fuel cells." As my dad - ex-nuclear - always likes to point out, the problem with renewable energy sources isn't just the amount of output, but when (and how reliably) it can be produced. Omitting a discussion of that - and talking in terms of mere output - would be the wrong approach to take. Sure, lower bounds can be obtained via such an approach, but if there's no room for or no technology for electrical energy storage, it's a bit of a moot point.

Michael Mitzenmacher said...

Anon 1: Some people appear not to believe in climate change (or, perhaps, simply believe the probable effects to be largely overstated). As MacKay points out, there are plenty of other reasons to look toward sustainable energy other than climate change. He wants to avoid the problem of having an argument break out as to whether climate change is important, when that's not the issue he's trying to discuss.

M -- rest assured he discusses efficiency issues. As you suggest there's multiple issues in efficiency -- in production of the energy, and in storage, for example -- and while I wouldn't claim to be an expert in them, he is. Read the book to find out more.

In some cases efficiency is a moving target, though, while the laws of physics provide some limitations worth knowing about.

Anonymous said...

I just spent pretty much my whole weekend reading this book. It's really good.

I know he wanted to focus on the physics rather than the economics, but it's hard to read about some of the hardware setups he talks about without thinking about maintenance costs. That 1000km by 1000km solar farm in the Sahara for instance---seems like you'd pretty much have to have little towns set up at various intervals between solar panels to house the people that would be needed to keep it in working order. And who would want to live and/or work in the middle of the Sahara?