What I am reading now: Sustainable Energy – Without the Hot Air

I have started reading this 2008 book by David MacKay, a Professor in the Department of Physics at the University of Cambridge in preparation for a book club discussion and want to share this finding with you!


The author wants his book to be read so it is available for FREE as a pdf download and also in a browser friendly format online! A 10-page synopsis is also available for download. And you are free to use all the material, including images and graphs, except for the cartoons and the photos with a named photographer.

Although the book is focused for the most part on the UK’s energy demand and supply what I like about this book is the attention given to NUMBERS (both for the UK and for the globe).

“We need simple numbers, and we need the numbers to be comprehensible, comparable, and memorable.” – David McKay

In keeping with the fossil energy theme for this month’s blog postings below is an excerpt from a chapter titled Sustainable Fossil Fuels?

“Take the known reserves of fossil fuels, which are overwhelmingly coal: 1600 Gt of coal. Share them equally between six billion people, and burn them “sustainably.” What do we mean if we talk about using up a finite resource “sustainably”? Here’s the arbitrary definition I’ll use: the burn-rate is “sustainable” if the resources would last 1000 years. A ton of coal delivers 8000 kWh of chemical energy, so 1600 Gt of coal shared between 6 billion people over 1000 years works out to a power of 6 kWh per day per person. A standard coal power station would turn this chemical power into electricity with an efficiency of about 37% – that means about 2.2 kWh(e) per day per person. If we care about the climate, however, then presumably we would not use a standard power station. Rather, we would go for “clean coal,” also known as “coal with carbon capture and storage”– an as-yet scarcely-implemented technology that sucks most of the carbon dioxide out of the chimney-flue gases and then shoves it down a hole in the ground. Cleaning up power station emissions in this way has a significant energy cost – it would reduce the delivered electricity by about 25%.
So a “sustainable” use of known coal reserves would deliver only about 1.6 kWh(e) per day per person.

We can compare this “sustainable” coal-burning rate – 1.6 Gt per year – with the current global rate of coal consumption: 6.3 Gt per year, and rising.

Our conclusion is clear:

Clean coal is only a stop-gap.

If we do develop “clean coal” technology in order to reduce greenhouse gas emissions, we must be careful, while patting ourselves on the back, to do the accounting honestly. The coal-burning process releases greenhouse gases not only at the power station but also at the coal mine. Coal-mining tends to release methane, carbon monoxide, and carbon dioxide, both directly from the coal seams as they are exposed, and subsequently from discarded shales and mudstones; for an ordinary coal power station, these coal-mine emissions bump up the greenhouse gas footprint by about 2%, so for a “clean” coal power station, these emissions may have some impact on the accounts.”

I encourage you to check out this resource which can help you and your students to view our energy future in a more realistic light.


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