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Soupjoe5 OP t1_ixrzam7 wrote

Article:

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A PLAN to use satellites in Earth’s orbit to harvest the Sun’s energy from space and beam it down to Earth using microwaves could be up and running as early as 2030, with the first-of-a-kind operational system delivering power into the grid by 2040.

The concept of harvesting solar energy in space is not a new one, but until now, high launch costs and limited technology have hampered progress, said Space Energy Initiative (SEI), the organisation behind the solar farm project.

However, recent developments in reusable rockets, and more modular SPS concepts, coupled with benefits that include clean, continuous base-load energy day and night, through all seasons and weather, and with much lower land usage than conventional renewables, is helping the idea gain traction. And with the potential of each satellite to beam around 2.9 GW of net power to a receiving antenna at a fixed point on Earth, it’s a concept that has even attracted the attention of the the UK Government. In July ministers announced that £3m (US$3.6m) in funding would be allocated to space-based solar power (SBSP) projects after confirming the engineering feasibility of the concept through an independent study.

But, to harvest energy comparable in power output to a nuclear power station takes a satellite that is incredibly large. According to SEI a typical system comprises a constellation of massive, kilometre-scale satellites 38,000 km above the ground in a geostationary orbit. At this range the massive satellites should not cause any problems with light pollution, SEI said.

Each has very lightweight solar panels and a system of mirrors to concentrate sunlight onto the panels, generating around 3.4 GW of electricity on the satellite. This is converted into RF microwave radiation, with an efficiency of 85%.

To allow the microwave beam to lock onto the correct point, an encrypted pilot beam is transmitted from the ground to the satellite. The maximum beam intensity is <250 W/m2, less than a quarter of the maximum sun intensity at the equator, and the system will be designed so that it is safe in the event that humans or birds or animals strayed into the beam, said SEI.

The ground rectifying antenna or “rectenna” as it is called then converts the electromagnetic energy into direct current electricity which passes through an inverter which delivers a net 2 GW of AC power into the grid.

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Soupjoe5 OP t1_ixrzgga wrote

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If SEI’s project, dubbed CASSIOPeiA, goes ahead, a cost modelling analysis by consultancy Frazer-Nash shows that the LCOE (levelised cost of electricity), used to compare different methods of electricity generation on a consistent basis, falls between £37 and £74/MWh, which is competitive with terrestrial renewable technologies, the organisation said.

Where the technology benefits greatly, is its availability. Compared with solar panels on the ground which are usually able to process 15–22% of solar energy into usable energy as conditions are never perfect, a solar power satellite in GEO can see the Sun for well over 99% of the time.

The idea of solar farms in space could get another big boost as ministers at the European Space Agency are meeting this week to discuss whether to fund a three-year preparatory programme known as SOLARIS. If approved, ESA said it would work in conjunction with European industry, to assess the feasibility, benefits, implementation options, commercial opportunities and risks of SBSP as a contributor to terrestrial energy decarbonisation. A decision whether to proceed with a full-blown project could then be made in 2025.

"The idea of space-based solar power is no longer science fiction," Sanjay Vijendran, SOLARIS’ lead scientist told the BBC.

"The potential is there and we now need to really understand the technological path before a decision can be made to go ahead with trying to build something in space."

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UniversalMomentum t1_ixs3n3r wrote

£37 and £74/MWh is quite cheap. As cheap as coal or gas on the high end and much cheaper on the low end.

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iNstein t1_ixtaqqx wrote

But can we make it even cheaper. Cheaper power gives us more options.

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Staerebu t1_ixwp1th wrote

Average LCOE for solar and offshore wind hit about 40 pounds per MWh a couple of years ago

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MaybeTheDoctor t1_ixt77zb wrote

What about just having 3-4 time the number of solar panels on earth - is that not a lot cheaper than to lift stuff into orbit ?

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iNstein t1_ixtalob wrote

That is what they are trying to figure out. No clouds, optimal alignment, no atmosphere and potentially generating power at night might change the equations. Time to find out.

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TotallyInOverMyHead t1_ixyozu7 wrote

AND: Micro asteroids /debris, no servicing, All eggs -> one Basket (if it gets a microasteroid hit in the right place, your giant sattelite is done for, vs. you replacing that particular solar pannel on earth).

Also, and i might be mistaken on this, given my HS level physiks skills were not that good back then, but being hit by a tightbeam of RF Radiation in 2-3 GW-Range surely must be a lifealtering event.

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ItsAConspiracy t1_ixyr14u wrote

Current designs would be redundant, with a large number of identical parts, of several types, self-assembled in orbit.

The satellite would be 22,000 miles out and incapable of sending a beam that tight. As the article mentions, the beam would be less concentrated than sunlight.

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TotallyInOverMyHead t1_ixz0uev wrote

Might you then not just be better off sending mirrors into space and making earth-based PV-cells generate power 24/7/365 ?

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ItsAConspiracy t1_ixz50pa wrote

That way you're still blocked by clouds. Also I'm not sure whether it's as feasible from geostationary.

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Riversntallbuildings t1_ixuma0h wrote

Thanks you for mentioning the efficiency of wireless transmission.

As renewable power production scales, it’s my hope that we have enough excess energy to begin using wireless transmission methods on earth.

It’ll be as difficult as hunting for the breakthrough in battery density and/or solar cell efficiency, but I’m optimistic that there are many more improvements that can be made with wireless power transmission.

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