tag:blogger.com,1999:blog-7338070402887246857.post2729033396243445224..comments2023-09-21T06:27:50.845-04:00Comments on Ramblings on the Future of Humanity: Solar Power Satellite Design ConsiderationsStephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-7338070402887246857.post-91752690814495924042012-02-12T06:04:33.194-05:002012-02-12T06:04:33.194-05:00Your math is correct.
A minor point: microwave re...Your math is correct.<br /><br />A minor point: microwave rectennas can achieve much higher conversion efficiencies than 60%; even 90%.<br /><br />More importantly, however, is that the 230 w/m2 is a design point that allows people (and wildlife) to thrive even when in the beam. If we don't care about cooking them, we can use much higher energy densities.<br /><br />Most importantly, that energy is available 24x7, while ground-based solar power doesn't work at night, when it's cloudy, or in early morning or late afternoon when the sun angle is too low, and the fraction of time of high sun angles varies by season. On average, ground solar is available perhaps 8 hours per day (more in dry deserts where you don't need it, less in high-latitude cloudy areas like the mid-west and north-eastern states where you need it most).<br /><br />A last point: solar radiance in space is 1367 w/m2, while on the ground is only about 1000 w/m2 even when the sun is shining directly overhead.Stephen D. Coveyhttps://www.blogger.com/profile/12946494775268235149noreply@blogger.comtag:blogger.com,1999:blog-7338070402887246857.post-40567695180862904322012-02-11T18:55:18.318-05:002012-02-11T18:55:18.318-05:00It appears to me that this would result in 230 w/m...It appears to me that this would result in 230 w/m2 at the earth. Given a 60% aperture efficiency this would be ~140 w/m2. Solar can be much higher, even if it has lower availability.<br /><br />Can you comment on whether the SPS is competitive?searphttps://www.blogger.com/profile/09833631140369094797noreply@blogger.com