Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.followup
Subject: Re: Alternate Energy & Microwaves
Message-ID: <4196@utzoo.UUCP>
Date: Thu, 9-Aug-84 20:45:47 EDT
Article-I.D.: utzoo.4196
Posted: Thu Aug  9 20:45:47 1984
Date-Received: Thu, 9-Aug-84 20:45:47 EDT
References: <565@hou2h.UUCP>
Organization: U of Toronto Zoology
Lines: 23

>> Microwaves have been proposed for power transmissions, but whenever I think
>> of microwaves carrying enough energy to actually be useful, I keep on seeing
>> all these birds, airliners, etc. flying through the beam and getting cooked.

Airliners are no problem; they have metal skins, which reflect microwaves
quite well.  The beam intensities are too low to have any gross effects on
birds, although there is some concern about long-term low-level effects
on them.  This is actually the most (!) serious known problem.

> The proposed SunSat (SPS, whatever) uWave beams carry less energy (even in
> the center of the beam!) than full sunlight; their advantage is that they
> irradiate the rectenna (RECtifying anTENNA, as I recall) 24 hrs/day and are
> unblocked by clouds...

They have another big advantage:  microwave-to-electricity conversion can
be quite efficient (70-80%), whereas converting sunlight to electricity is
dismally inefficient (15% is good for solar cells).  Of course, the power
satellite itself probably uses solar cells, but it is out in space,
where (a) the sun shines 24 hours/day, and (b) the waste heat does not
go into Earth's biosphere.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry