In a joint project with Mitsubishi Heavy Industries, JAXA (Japan Aerospace Exploration Agency) recently tested an energy transmission system using microwave beams. One test involved the transmission of energy at 1.8 Kilowatts over a distance of 50 metres, and a second test transmitted 10 Kilowatts a distance of 500 metres.
Although the distances and power levels used were very small, the tests demonstrated that power beaming can be done very accurately and with reasonable efficiency. The transmission of energy from power satellites in Geostationary Orbit, has been seen as one of the main challenges of this technology - actually getting the satellites into space is currently very expensive but it is at least known to be possible.
JAXA does not expect to have working power satellites in place until at least 2030, and many detractors are already dismissive of their ability to do that and of the need for power satellites even if they can be made to work. Nuclear power, wind farms, ground based solar technology, and other renewables are seen by many as sufficient to supply the world's needs in the foreseeable future, as these technologies become cheaper and more efficient. Operating large power generation and transmission systems in high orbits is seen as impossible to achieve profitably.
Yet, all of the problems with power satellites are solvable. Launch costs can be made much cheaper using ISP technology, which will lower the cost of construction and maintenance of power satellites. Radiation and meteorite shielding, and orbit cleansing laser arrays can prevent damage to the power satellites in space. Even the problem of overcrowding in GEO can be avoided by placing the power satellites in non-geostationary orbits orbits and using solar sails to maintain their position relative to the Earth's rotation. Receiving stations on the ground for a 1Gw generator would be about 10Km in diameter. These could be placed at some distance from major cities since the transmission loss for high-tension cables is only about 1% per 150Km. The receivers could even be placed off shore enabling the reception of energy in quantities that would easily supply the total needs of the entire world.
Power satellites would easily be profitable if the cost of the space side of construction can be lowered to less than 1 % of its current costs - and that is not difficult to do since we currently have no space industry to speak of. All current space activity is done at research and exploration cost levels on set piece missions where there is no thought of profitability. Low cost space flight is achievable with current technology and the time to start doing it is now. Some detractors always say wait another few years and it will be even easier - we'll have graphene products and quantum computers etc. That's true up to a point, but the fact is the major technology requirements for a space economy are already met. Our current materials are good enough, our current ICT technology is fast enough, small enough and cheap enough, and we have enough knowledge of space operations to implement a space industry. We need to get the show on the road and there's no time like the present.
Arrays of offshore receiving meshes could power the entire world with no significant environmental impact. The area under the rectannae could be used for various purpose such as sea food farming. A 1Gw receiving station would be much cheaper to construct and maintain compared to other technologies and produce its full capacity on a continuous basis - not just for a few hours per day like a solar power station or wind farm. Energy is wealth and this great wealth would pay for a space industry and let it expand into even more profitable areas such as asteroid mining and high quality space manufacturing - then you'll get better products than you ever would have sitting around on Earth waiting for a miracle breakthrough.