A construction of a land-based rectenna for space solar power reception need not create similar problems. The construction damage to land sites can be minimized by designing the rectenna to work without requiring leveling of the site - using pylons and a suspended structure, for example. In addition, as mentioned earlier, the rectenna can be built in modules off-site, then shipped in and assembled. Damage to off-shore sites may necessarily be more severe. In most ocean sites under consideration (North Sea, etc.) at least the perimeter of the rectenna will need to be protected with a sea-wall. Construction of this sea-wall will destroy the sea-floor habitat under it If the rectenna is to be placed in a polder, even more sea-floor habitat will be destroyed by draining. 6.3.2 Climate and Socio-Economic Modification After construction is finished, the site will likely be much calmer. This obviously doesn't mean the rectenna will cease to be a factor in the local ecology and society. Climate Modification by Rectenna Operation Even if the construction doesn't destroy the local ecosystem, the design of the rectenna might unacceptably alter the local ecology. The porosity of the rectenna to sunlight, wind, water currents, and precipitation is one issue. The other issue is ongoing pollution from the operation of the rectenna. Any land-based rectenna design is going to reduce the amount of sunlight striking the surface below it. In addition, the structure may act as a wind-break. It may also block necessary precipitation from reaching the plants below. Finally, depending on the vegetative cover and erosion characteristics of the soil underneath, precipitation may need to be trapped and channeled to a prepared drainage system. These effects will change the ecology and micro-climate of the areas under and around the rectenna - the exact changes depend upon the design of the rectenna and the site selected. For off-shore rectennas, even if the rectenna is placed on a series of towers, normal currents and seafloor motion will be restricted by the necessary sea-wall. If the rectenna is placed in a pumped-dry polder, the sea-floor and water-borne habitat will be destroyed. In the first case, the resulting structure might allow a new, more diverse water-borne ecology to develop than is normal - in essence an artificial reef. If the rectenna is built in a polder, the water-borne habitat might be replaced by agriculture or wild “island” habitat. Unlike fossil fuel power plants, a satellite power reception system will not produce chemical pollution from combustion - the largest source of ongoing pollution will come from waste heat produced during operations. (The effects of micro-wave and near-IR laser irradiation on the surrounding ecology were considered previously.) Satellite power reception systems are likely to have a lower quality of waste heat than other types of power plants. The waste heat is also likely to be dumped in an uncontrolled manner. However, because the power conversion in a rectenna is not accomplished via a turbine that requires a large temperature difference between input and output, the total amount of waste heat produced by a satellite power system rectenna will be less than that from traditional power plants. In addition to the rectenna, the impact statements for each site must consider the power grid links, support buildings and maintenance activities. All these will produce continuing effects on the local climate and will affect wildlife habitat. Socio-Economic Effects of Rectenna Operation The socio-economic effects of rectenna operation are much less than those from construction. The number of jobs required for operation and maintenance will be a noticeable income source only for small communities. The numbers required (on the order of 100 people for a 2 km square facility) are easier to integrate with the surrounding communities' social structure - especially if local hiring is used [ERG, 1980]. The big question will be - who owns rectenna? If a private company is the owner, the local government is likely to gain a large increase in it's tax base (assuming property taxes are used to raise revenue). On the other hand, if the facility is owned by a government or quasi-govemmental entity, the local community tax base will not increase as much [ERG, 1980]. This will be significant when dealing with the secondary economic growth that the rectenna is likely to produce. Without an increase in the tax base, the government will find it more difficult to provide needed municipal and utility services.
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