{"id":147,"date":"2009-10-04T15:44:51","date_gmt":"2009-10-04T21:44:51","guid":{"rendered":"http:\/\/energyrealist.com\/?page_id=147"},"modified":"2021-01-30T19:10:15","modified_gmt":"2021-01-31T00:10:15","slug":"energy-101","status":"publish","type":"page","link":"https:\/\/energyrealist.com\/?page_id=147","title":{"rendered":"Energy 101"},"content":{"rendered":"

In high school we learnt that energy cannot be created or destroyed.  So why all this concern about using energy?<\/p>\n

I really can’t put it better than MacKay*:<\/p>\n

“Isn\u2019t energy conserved? We talk about \u201cusing\u201d energy, but doesn\u2019t one of the laws of nature say that energy can\u2019t be created or destroyed?
\nYes, I\u2019m being imprecise. This is really a book about entropy \u2013 a trickier thing to explain. When we \u201cuse up\u201d one kilojoule of energy, what we\u2019re really doing is taking one kilojoule of energy in a form that has low entropy (for example, electricity), and converting it into an exactly equal amount of energy in another form, usually one that has much higher entropy (for example, hot air or hot water). When we\u2019ve \u201cused\u201d the energy, it\u2019s still  there; but we normally can\u2019t \u201cuse\u201d the energy over and over again, because only low entropy energy is \u201cuseful\u201d to us.   …It\u2019s a convenient but sloppy shorthand to talk about the energy rather  than the entropy,…”<\/em><\/p>\n

(*from “Sustainable Energy – without the hot air” by David JC Mackay www.withouthotair.com<\/a> – which, if I had the knowledge and skill, would be the book I would have liked to write…)<\/p>\n

The other way to think about this idea is to think of concentrated versus distributed “energy” (and we will drop the quotation marks from here on).<\/p>\n

So electricity in a high-voltage distribution line is concentrated, while the heat given off by an electric radiator, once it’s been convected around a room in the form of warmed air is quite diffuse.  This of course makes oil and its derivatives such an ideal energy source; easy to transport, easy to store, easy to ignite, and full of concentrated energy.<\/p>\n

We could split the discussion of alternative energy sources into those where we take diffuse energy, like sunlight and wind, and turn it into concentrated energy like electricity – which in turn enters the existing energy distribution system.  Turning biomass or algae into liquid fuel is much the same, except that we have intermediate (and, in the realists opinion, wasteful) steps of turning sunlight into a complex biological entity, and then refining that back into a simple volatile hydrocarbon.<\/p>\n

On the other side we have processes where we use relatively diffuse energy, “concentrate”  it somewhat, and use the diffuse energy for diffuse purposes.   In plain language; why use concentrated energy that can melt metal, like electricity or oil and gas flames to heat water, which is then pumped around a house to raise the inside temperature by a few degrees?  The only reason to do that is because the fuel has to be transported to the house and electricity lines, gas pipes and oil tankers are a very convenient way of transport.  If the energy can be gathered at the house directly, by solar hot water panels for instance, the warm water so generated is quite enough to heat the house to a comfortable level.  After all we frail humans only have a very limited comfort zone, and water even at a paltry 180F is much too hot for us.<\/p>\n

For a formal discussion on energy here is the Wikipedia entry<\/a>.<\/p>\n

Energy sources<\/h2>\n

The various sources of energy are covered in exhaustive detail elsewhere (in books and countless web sources), but for sake of completeness here are the major sources we can realistically use:<\/p>\n

The SUN<\/strong><\/p>\n

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\"sun<\/p>\n

– directly of course, but also in a long list of indirect ways:<\/p>\n