As many of you know, I try to publish an original column every week. The rhythm of it suits my nature, and I take some satisfaction in averaging nearly 50 columns per year. Alas, sometimes other priorities intervene, and this is one of those times. 

It occurred to me when Aaron Keck and I were discussing Why Solar Roads are a Bad Idea on air that I should have included a link to a column I wrote a couple of years ago called Electricity Production 101. Let me explain why.

The fatal flaw in solar roads is that they generate direct current (DC) power, which is difficult to transmit over long distances without significant loss of power. Alternating current (AC) power can be transmitted over long distances with only a small loss of power. This difference in transmission losses explains why electricity transmission around the globe uses AC rather than DC.

Had I included a link to Electricity Production 101, it would have provided a more complete picture. I invite you to follow the link to get more detail on the science, but leave you with these key points on electricity:

  • To make AC power you need to spin something. Generally speaking, this is accomplished by:
    • Burning coal or natural gas to make steam and letting the steam flow through a turbine which makes the turbine spin.
    • Using the heat from a uranium fuel rod (nuclear power) to make steam.
    • Letting wind spin a propeller.
    • Building a dam and directing falling water through a turbine.

 

Lastly, when you read about solar power these days, you need to distinguish between solar electric, which are the panels you see on roofs, and solar thermal. Solar thermal power plants, which are being built in the southwestern United States, use mirrors to concentrate the energy from the sun to boil water and make steam. This is an intriguing way to use the sun to make AC current.

I will be back next Sunday the 21st with an update on the Chikungunya virus epidemic in the Caribbean.

As always, if you have a comment or question, use the interface below or send me an email at commonscience@chapelboro.com. To get additional updates on topics that have been in my columns and other science and technology news, follow my Twitter feed on @Commonscience.