According to my own estimates in the posts below, it's only a factor
of about 3.4, even using today's PV and energy storage / transmission
efficiencies. Upgrade the efficiencies to 30% and 70% and the land
area required for ground-based becomes lower than for SSP. I'd like
to see both of those reports.

The current figure for land required for ground-based using today's
methods *is* positively huge: 400.4 thousand square Km. ...That's
two-thirds the size of Texas. Those efficiencies are going to have to
go up *greatly* to even talk realistically about powering all the
energy needs of the U.S. with ground-based solar. However the land
needs for SSP are fairly huge as well: 117.4 thousand square Km;
that's the same land area as Virginia.

--- In spacesettlers@yahoogroups.com, "Combs, Mike" wrote:
>
>> Nope. Not "quite a bit smaller" at all, not if all the energy needs are
>> going to be met, instead of just baseline electrical energy needs.
>
> Quite a bit smaller for the same total amount of energy delivered.
> I remember back in the day initially seeing a comparison between
> rectennas and ground-based solar arrays indicating the former would
> only take up 1/40 the land area as the latter for the same total
> amount of power overall. Then later I saw the number changed to
> 1/30. But even with the later estimate, we're far better off
> surrendering land to rectennas than to ground-based solar arrays.

--- In spacesettlers@yahoogroups.com, "William" wrote:
>> 3707.1 Gw / 5 Gw per installation = 742 rectenna installations
>> required.
>
> rectenna installation area = 158.3 km2.
>
> total area needed = 742 * 158.3 = 117393 km2.

--- In spacesettlers@yahoogroups.com, "William" wrote:

On 2/9/12 9:00 AM, William wrote:

> The current figure for land required for ground-based using today's
> methods *is* positively huge: 400.4 thousand square Km. ...That's
> two-thirds the size of Texas.

Is that including the land for whatever enormous power-storage system
you use to keep the lights on at night (or on cloudy days)?

Best,
- Joe

I factored in an extra 50% of land for anything else besides the PV's:
power lines, panel supports, roads, latitude adjustment for spacing
the tilted PV's, etc. That would also include the power-storage (or
conversion to fuel) "enormous" or not.

--- In spacesettlers@yahoogroups.com, Joe Strout wrote:

On 2/10/12 12:36 PM, William wrote:

> I factored in an extra 50% of land for anything else besides the PV's:
> power lines, panel supports, roads, latitude adjustment for spacing
> the tilted PV's, etc. That would also include the power-storage (or
> conversion to fuel) "enormous" or not.

Seems reasonable enough to me, if a bit hand-wavy (but hand-wavy
reasoning is far better than no reasoning at all!).

Best,
- Joe