How Japan Plans to Build an Orbital Solar Farm

本帖最後由 toylet 於 2015-3-19 20:35 編輯

Imagine looking out over Tokyo Bay from high above and seeing a man-made island in the harbor, 3 kilometers long. A massive net is stretched over the island and studded with 5 billion tiny rectifying antennas, which convert microwave energy into DC electricity. Also on the island is a substation that sends that electricity coursing through a submarine cable to Tokyo, to help keep the factories of the Keihin industrial zone humming and the neon lights of Shibuya shining bright.

Here Comes the Sun: Mirrors in orbit would reflect sunlight onto huge solar panels, and the resulting power would be beamed down to Earth.

But you can't even see the most interesting part. Several giant solar collectors in geosynchronous orbit are beaming microwaves down to the island from 36 000 km above Earth.

It's been the subject of many previous studies and the stuff of sci-fi for decades, but space-based solar power could at last become a reality—and within 25 years, according to a proposal from researchers at the Japan Aerospace Exploration Agency (JAXA). The agency, which leads the world in research on space-based solar power systems, now has a technology road map that suggests a series of ground and orbital demonstrations leading to the development in the 2030s of a 1-gigawatt commercial system—about the same output as a typical nuclear power plant.

It's an ambitious plan, to be sure. But a combination of technical and social factors is giving it currency, especially in Japan. On the technical front, recent advances in wireless power transmission allow moving antennas to coordinate in order to send a precise beam across vast distances. At the same time, heightened public concerns about the climatic effects of greenhouse gases produced by the burning of fossil fuels are prompting a look at alternatives. Renewable energy technologies to harvest the sun and the wind are constantly improving, but large-scale solar and wind farms occupy huge swaths of land, and they provide only intermittent power. Space-based solar collectors in geosynchronous orbit, on the other hand, could generate power nearly 24 hours a day. Japan has a particular interest in finding a practical clean energy source: The accident at the Fukushima Daiichi nuclear power plant prompted an exhaustive and systematic search for alternatives, yet Japan lacks both fossil fuel resources and empty land suitable for renewable power installations.

Soon after we humans invented silicon-based photovoltaic cells to convert sunlight directly into electricity, more than 60 years ago, we realized that space would be the best place to perform that conversion. The concept was first proposed formally in 1968 by the American aerospace engineer Peter Glaser. In a seminal paper, he acknowledged the challenges of constructing, launching, and operating these satellites but argued that improved photovoltaics and easier access to space would soon make them achievable. In the 1970s, NASA and the U.S. Department of Energy carried out serious studies on space-based solar power, and over the decades since, various types of solar power satellites (SPSs) have been proposed. No such satellites have been orbited yet because of concerns regarding costs and technical feasibility. The relevant technologies have made great strides in recent years, however. It’s time to take another look at space-based solar power.

A commercial SPS capable of producing 1 GW would be a magnificent structure weighing more than 10 000 metric tons and measuring several kilometers across. To complete and operate an electricity system based on such satellites, we would have to demonstrate mastery of six different disciplines: wireless power transmission, space transportation, construction of large structures in orbit, satellite attitude and orbit control, power generation, and power management. Of those six challenges, it's the wireless power transmission that remains the most daunting. So that’s where JAXA has focused its research.

Wireless power transmission has been the subject of investigation since Nikola Tesla's experiments at the end of the 19th century. Tesla famously began building a 57-meter tower on New York’s Long Island in 1901, hoping to use it to beam power to such targets as moving airships, but his funding was canceled before he could realize his dream.

To send power over distances measured in millimeters or centimeters—for example, to charge an electric toothbrush from its base or an electric vehicle from a roadway—electromagnetic induction works fine. But transmitting power over longer distances can be accomplished efficiently only by converting electricity into either a laser or a microwave beam.

The laser method’s main advantages and disadvantages both relate to its short wavelength, which would be around 1 micrometer for this application. Such wavelengths can be transmitted and received by relatively small components: The transmitting optics in space would measure about 1 meter for a 1-GW installation, and the receiving station on the ground would be several hundred meters long. However, the short-wavelength laser would often be blocked by the atmosphere; water molecules in clouds would absorb or scatter the laser beam, as they do sunlight. No one wants a space-based solar power system that works only when the sky is clear.

But microwaves—for example, ones with wavelengths between 5 and 10 centimeters—would have no such problems in transmission. Microwaves also have an efficiency advantage for a space-based solar power system, where power must be converted twice: first from DC power to microwaves aboard the satellite, then from microwaves to DC power on the ground. In lab conditions, researchers have achieved about 80 percent efficiency in that power conversion on both ends. Electronics companies are now striving to achieve such rates in commercially available components, such as in power amplifiers based on gallium nitride semiconductors, which could be used in the microwave transmitters.

In their pursuit of an optimal design for the satellite, JAXA researchers are working on two different concepts. In the more basic one, a huge square panel (measuring 2 km per side) would be covered with photovoltaic elements on its top surface and transmission antennas on its bottom. This panel would be suspended by 10-km-long tether wires from a small bus, which would house the satellite’s controls and communication systems.

Using a technique called gravity gradient stabilization, the bus would act as a counterweight to the huge panel. The panel, which would be closer to Earth, would experience more gravitational pull down toward the planet and less centrifugal force away from it, while the bus would be tugged upward by the opposite effects. This balance of forces would keep the satellite in a stable orbit, so it wouldn’t need any active attitude-control system, saving millions of dollars in fuel costs.

Full Article: ... -orbital-solar-farm

日本在1981年提出一個發展智慧型電腦的計畫,期望在1990年代能製造出一種能夠學習、推理、了解語音與影像並以自然語言和人類交談的電腦。日本人稱這類的電腦為第五代電腦。   第五代電腦結合了4種目前發展中的技術:(1)知識庫專家系統(Knowledge Based Expert System);(2)超高階程式語言(Very High Level Programming Language);(3)分散式計算(Decentralized Computing);(4)超大型積體電路(Very Large Scale Integration)技術。   知識庫專家系統組合了經過組織的知識,提供使用者簡捷有效率的推論和解答,並提出建議。這個系統並以具親和力的方式與使用者溝通,包含影像及自然語言等溝通方式。   超高階程式語言允許程式設計師告訴電腦「我要執行的是什麼」而不是「我要如何去做」,大幅減輕程式設計師的負擔並縮短程式開發時程。   大量使用平行處理是第五代電腦的一大特徵,多處理器的構成方式包含利用分散各地的電腦藉由網路連接運作,或是同一電路板上由多個微處理器構成的系統。   超大型積體電路的技術提供了價格低而有效率的晶片,使得電腦運算速度與可靠性大幅提升,配合第五代電腦繁複計算的需要。





本帖最後由 toylet 於 2015-3-20 16:09 編輯
Rabe 發表於 19/3/2015 21:41

無錯! 軌道微波炮!  

Gundam 00 2nd Season 第 13 集 的 Memento Mori!


patwong1998 發表於 20/3/2015 10:29

Gundam X 嗰支要兮月球射出, 矩離遠!


Gundam 00 ........


Gundam 00 ........
dom 發表於 22/3/2015 12:48

咁樣算不算是一種 巴別塔 (Tower of Babel)?
若等同的話, 傳說 神 會 干預.....
巴別塔(希伯来语:מגדל בבל‎ Migdal Bavel;也译作巴貝爾塔、巴比伦塔,或意译爲通天塔),巴別在希伯來語中有「變亂」之意。[1]據《聖經·創世記》第11章記載,當時人類聯合起來興建希望塔頂通天能傳揚己名的高塔。為了阻止人類的計劃,上帝讓人類說不同的語言,使人類相互之間不能溝通,計劃因此失敗,人類自此各散東西。



本帖最後由 良優 於 2015-4-1 16:17 編輯



回覆  toylet
就算佢改左做武器..我諗佢應該只可以發一炮就會俾其他國家擊落 ...
良優 發表於 23/3/2015 02:33