Leapfrogging: Energy scavenging

I just came across an interesting article in the Economist on wireless electricity transmission. The technology has been commercially available for a few years, but only for charging cell phones at very short ranges (e.g. see here and here). A slightly longer range (several feet) version was demonstrated at TED last year. But the really exciting stuff comes from the idea of “energy scavenging” (or “harvesting” — but that doesn’t sound as subversive or exciting). Basically, the concept is to make electricity out of the ambient energy produced by radio, television and mobile phone transmitters. Think of this as recycling, since much of that energy goes to waste: just visualize how many electromagnetic waves must be traveling everywhere to reach all the devices that use them.

This technology interests me because of the potential for leapfrogging. New technology is developed slowly, building on whatever came before it. A country at the leading edge has no choice but to suffer through the process, which can look odd in retrospect (e.g. home appliances that plug into light bulb sockets and the QWERTY keyboard.) However, developing countries often provide a context where the old thing isn’t being used yet, so they might as well jump straight to the new thing. That’s leapfrogging.

Cell phones are the obvious example. Many developing countries never bothered with land lines, they just went straight to cell networks. As I post this, my internet connection is through something that looks like a desk phone with an antenna sticking out. It connects to Uganda Telecom’s cell network. It’s the only way to get internet here. (On a related note, here are some good tips on staying connected while traveling in Africa – with a nod to Texas in Africa.)

Even though cell phones are everywhere around Mbale, electricity is not. Many rural households are off the grid. The reason is simple economics: think about the differing cost structures of launching a cell phone network versus wiring the same area to an electricity gird. This also creates business opportunities, as I’ve seen shops in town advertising “Cell Phone Charging” (though I’ve yet to ask how much it costs). Nokia has recently announced a bike-mounted cell phone charger, a device that is technologically very simple, but is only now seeing a market.

Unsurprisingly, Nokia is also involved in the electricity scavenging research. As described in the Economist article, they have developed a way to harvest up to 5 milliwatts of power — about a tenth of what will be needed to trickle-charge a phone. So this technology still needs some work. Fortunately, there’s a profit motive at work that can push the R&D forward.

I tend to be an optimist about technological progress, but a pessimist about its ability to tackle development problems. High tech development solutions are often over-hyped. Still, I’m hopeful for energy harvesting. I like seeing environmental benefits and communications technology come together. Of course, potential applications go beyond communications: perhaps one day whole cities and regions will develop where everything is powered without the expensive and inefficient electricity grids that we have now.

I do have one nagging concern: the laws of physics, specifically conservation of energy. One energy harvesting phone may be pulling in wasted radio waves. But what if every phone did that? Would we see a drop in signal quality? Would the telecom company want to be paid for the electricity it provides? Would there be a way to prevent people from accessing your network? Could we sign up for electricity providers (for our phones, computers, refrigerators, cars?) the way we sign up for phone service? These questions won’t be relevant for a couple decades. Still, it’s fun to ponder…