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The dream of long-range wireless power transmission (WPT), pursued by Nikola Tesla in the nineteenth century, and more recently by the US Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA) (remember solar power satellite (SPS) systems, proposed in the 1970s?), is also alive and well. Powercast, a Pittsburgh-based company, has developed a range of wireless-charging products based on RF energy harvesting, which promise to deliver "milliwatts over meters" and "watts over meters" for charging low-power lighting and wireless sensors, among potential applications. Unfortunately, the RF power needed to charge cell phones and laptops over moderate distances may not pass muster with the regulators, because of potential human health hazards. Power-Beam, a Silicon Valley startup, which replaces radio waves with low-power laser beams for wireless charging, may also encounter regulatory hurdles.