คลังสมองจามจุรีและเพื่อนโรงไฟฟ้าในอวกาศเมื่อไม่กี่วันมานี้ ได้มีเรื่องตื่นเต้นเกิดขึ้นในวงการพลังงานครับ คือทางญี่ปุ่นเค้าประกาศว่า เค้าประสบความสำเร็จ
ในการทดลองส่งพลังงานไฟฟ้าขนาด 10 กิโลวัตต์ แบบไร้สายผ่านอากาศจากที่หนึ่งไปอีกที่หนึ่งในระยะ 500 เมตร
ครับ นับเป็นก้าวสำคัญที่จะทำให้การส่งกระแสไฟฟ้าที่ผลิตจากแผงโซลาเซลล์ขนาดใหญ่จากอวกาศ ลงมายังพื้นโลก
มีความเป็นไปได้มากขึ้นครับ
ญึ่ปุ่นเตรียมสร้างโรงไฟฟ้าพลังงานแสงอาทิตย์ในอวกาศ ที่มีกำลังผลิตขนาด 1 กิกะวัตต์ (เทียบเท่ากับโรงไฟฟ้า
นิวเคลียร์ 1 โรง) ภายในปี ค.ศ. 2030 โดยโรงไฟฟ้าในอวกาศจะลอยในวงโคจรที่ระยะห่างจากโลก 36,000 กิโลเมตร
ซึ่งจะทำให้เหมือนลอยอยู่ที่เดิมเมื่อเทียบกับพื้นโลก พลังงานไฟฟ้าจากแสงอาทิตย์จะถูกเปลี่ยนไปเป็นคลื่นไมโครเวฟ
แล้วยิงส่งลงมาที่สถานีฐาน ที่ลอยอยู่นอกชายฝั่ง จากนั้นคลื่นไมโครเวฟจะถูกเปลี่ยนเป็นกระแสไฟฟ้า และนำส่งเข้าสู่
ระบบจ่ายไฟฟ้า
Japan Demoes Wireless Power Transmission for Space-Based Solar Farms
By Evan Ackerman
Posted 16 Mar 2015 | 21:00 GMT
Illustration: iStockphoto
With a few exceptions, sources of renewable energy tend to be inconveniently unreliable. Things like wind
and wave energy are subject to the whims of weather, and even if you manage to find something that isnt
weather dependent (like tidal flow), you still cant rely on a constant output of power. Strictly speaking,
solar power is the worst: it's heavily weather dependent, and half the time, it doesn't work at all.
(Even the moon gets in the waysometimes.)
Some think the way to make solar power the backbone of a renewable energy economy is to avoid the
problematic Earth entirely and head out into space, where the sun is always shining and weather means
something entirely different. Solar power satellites (SPS) are more than a concept: its an area of active
research and development, led by the Japan Aerospace Exploration Agency (JAXA). JAXA explained
its 25 year technology development roadmap that culminates in a 1 gigawatt SPS sending solar power back
to Earth in the 2030s in IEEE Spectrum last year. Last week, JAXA and Mitsubishi demonstrated their progress
on one of the most difficult components of that system: long range wireless power transmission.
Space-based solar power on a commercially viable scale will be an enormous undertaking. For an output
of 1 gigawatt, Japan is planning on deploying a solar collector weighing over 10,000 metric tons and
measuring several kilometers across. It would live in geosynchronous orbit, some 36,000 kilometers from Earth.
Photo: Mitsubishi Heavy Industries
Phasers Locked on Target: In a test of space-based solar power, Mitsubishi Heavy Industries and JAXA sent
10 kilowatts 500 meters by microwave. Arguably, the most difficult part of this whole business (from a technological
perspective) is getting the power from the satellite back down to Earth where we can actually use it, and until
we can find a long enough extension cord, there's only one way to make it work: wirelessly.
The only efficient ways to transmit power wirelessly over a very long distance, according to JAXA researchers,
is with either lasers or microwaves. Lasers are impractical because theyd run into the same problems that
solar power does on Earth: they don't work through clouds. Microwaves, though, work even if the weather is bad,
so they're what JAXA has been planning on using to transmit power.
On Thursday, JAXA was able to deliver 1.8 kilowatts with pinpoint accuracy to a receiving antenna (rectenna)
55 meters away using carefully directed microwaves. According to JAXA, this is the first time that anyones
been able to send such a high power output with this level of direction control. Also on Thursday, Mitsubishi
(in partnership with JAXA) managed to send 10 kilowatts of power over a distance of 500 meters,
using larger antennas with more of an emphasis on power over precision.
The obvious question here is one of efficiency: being able to transmit power is great, but if you lose most
of it along the way, will the overall system ever reach commercial viability? At this point, the conversion system
(solar to DC to microwave to DC to AC) is about 80 percent efficient, but that excludes loss of energy in transit.
Neither JAXA nor Mitsubishi are commenting on the efficiency of these specific tests (which, to be fair, weren'tt
optimized for efficiency), but we do know that as of last year, JAXA expected a 1.6 kilowatt microwave beam
to yield a rectenna output of about 350 watts from a 50 meter test.
Within the next five years or so, Mitsubishi is hoping that theyll be able to use this system for short range
high power delivery (like electric car charging), and medium range delivery of small amounts of power
(like powering warning lights on transmission towers). Meanwhile, JAXA is planning on testing the technology
in space by 2018, with a small satellite transmitting several kilowatts from low Earth orbit to a microwave
receiver on the ground. JAXA hopes to have a 100 kW satellite in orbit by 2021, and a 200 MW version
by 2028. By 2031, if everything goes well, a 1 gigawatt commercial pilot plant will be in operation,
with a full on commercial space-based power industry to kick off with one launch per year starting in 2037.
