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Graphic Series: Earthly Ideas, High Voltage Direct Current

This week's cartoon describes high voltage direct current (HVDC), an efficient alternative method for transmitting bulk power. Many people are hopeful that this technology will allow use of renewable energy sources to grow, because it can take power generated in remote locations and carry it for long distances without losing too much energy along the way. Since wind farms and solar fields are often far from cities and towns, this is an exciting possibility. You can read more about HVDC in the article Clean Power From Deserts.

Click image to enlarge

Editor's note: This post is part of a series featuring Worldchanging ally Andy Lubershane's original graphics. While many of the issues covered in the comics have been discussed on Worldchanging in the past, we hope that you'll be able to use this new medium in a different way … whether it's in your classroom, on your office wall, or to help explain ideas to friends and family.

Andy Lubershane researches, writes and cartoons about sustainability from his home in Boston. Check out more of his illustrations here

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Nice and clever graphics. However, I assume it's unfinished as it doesn't explain how to lower the voltage to suit existing appliances. Or am I missing anything?

Posted by: Funtomas on 27 Feb 09

It's a nice thought, but in order to transmit the same electricity in direct current you would need high tension power lines that were thirty feet thick and made of solid copper. Figure out a green way to go about doing that, or any way to do that, and you've got yourself a nobel prize.

Posted by: Patrick Abbott on 28 Feb 09

Patrick Abbot, The whole point of HVDC is you don't need 30 ft. thick transmission lines because you use high voltage and it's already being used to shift power under bodies of water (Georgia Straight, Great Lakes etc.) and between unsynchronized grids.

It's not the alternating current that lets you use skinny wires, it's the high voltage that lets you use skinny wires. If anything AC is less efficient than DC because it radiates energy to the environment. Alternating current was chosen over direct current about a century ago because there was no cheap way to step DC up and down in voltage. That's what 'transformers' do with AC. Now we have semiconductor devices called thyristors which can do the job reliably.

Posted by: thorneycroft on 28 Feb 09

Yeah you got it, i read up on it after posting, which is a silly way to go about things. turns out college physics isn't what its cracked up to be. Still, the insinuation that AC transmission is a dirty way to do things and DC is the green way to do things is still misleading. HVDC will help future continental projects be feasible, but theres no need to dirty the name of something that is already there for good reason. smoke clouds, i'm looking at you.

Posted by: Patrick Abbott on 1 Mar 09

Hey Funtomas,

Thanks for the comment: There are ways of reducing the voltage back to acceptable levels for appliances once the power reaches users - otherwise HVDC wouldn't be useful at all. I guess I should add that to the comic!

Posted by: Andy Lubershane on 2 Mar 09

I agree. The fourth panel simply states that HVDC is better for long distance, without giving so much as a hint of an explanation or rationale. So I'm not sure what this cartoon actually accomplishes; for me, at least, it fails to illuminate in any meaningful way.

That being said, it did at least pique my interest in HVDC transmission, which I'm now researching.

Posted by: neilw on 4 Mar 09

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