Energy Harvesting Is What Fuel Cells Want to Be

by Linnea Brush
April 2, 2007

The interest in energy harvesting is what most “emerging technology” companies dream about. Certain problems present certain opportunities, and right now the problems with batteries are a big market driver. Everyone is stepping up to the plate to address these problems, including the battery companies themselves (with “new” technologies like vanadium, zinc-air and others). Semiconductor companies seem to have accepted that batteries aren’t going away, so they are providing products to overcome their limitations. Ultracaps perform a similar function. And then you have fuel cells.

No technology has been so promising for so long. Fuel cells have been touted as a battery replacement for many years, but a multitude of problems have plagued their acceptance. It is never a good idea to present a solution that has as many problems as what it is proposing to answer (even if they are different problems). And it’s even worse when something comes along that could leapfrog the technology before it even has a chance to succeed. Like energy harvesting.

Energy harvesting encompasses a range of processes by which energy is captured and stored. Energy sources include light, vibration, thermal gradients, pressure, motion and piezoelectric (e.g. manual depression of push-button switches). Energy harvesting is getting increased attention in certain applications (such as wireless mesh networks) due to the problems with batteries. In this case, the problems are maintenance and replacement, which are a major expense.

Applications that are appropriate for energy harvesting include hard-to-reach locations or where it would be too costly to replace large numbers of batteries. Another are applications that can’t use batteries at all, usually because of the harshness of the location. Going down the list, it becomes pretty obvious that these also describe the early adopter segments that fuel cells have targeted.

From here, the competition gets even closer. Energy harvesting’s long-term goal is to go after the portable device market, such as mobile consumer devices. Not necessarily cell phones and laptops, but I’m sure they’re not ruling them out. The path to market is remarkably similar with both energy harvesting and fuel cells – in purpose, intent and goals.

A big difference is that fuel cells are trying to find their place in society. They are still going after niche markets, while energy harvesting has already achieved mainstream status in conventional, commercial wiring applications. According to the Fraunhofer Institute, energy harvesting prices are “comparable to existing battery solutions” in industrial and commercial applications. And in some commercial applications, these solutions can actually be cheaper and easier to install. Fuel cells can’t approach that.

Fuel cells aren’t out of the running, however. Since energy harvesting is so new (and reliability could still be a problem), it is being used with battery back-up. As microgenerators improve, batteries will be removed, according to Fraunhofer. Fuel cells could replace batteries in low-power applications where batteries do not pose problems. Still, it must be frustrating to realize that energy harvesting is going beyond batteries and is already a cheaper alternative than fuel cells.

Technical challenges face energy harvesting technologies, as well. One company told me that, “If anyone gets a reasonable power density from an energy harvesting device that can operate in an industrial temperature range, they will win big.” Go to it, guys!

Finally, there is one area that fuel cells and energy harvesting must meet: consumer price points. Home/residential/consumer applications have lower pricing points than either technology currently achieves. It’s going to be a while before fuel cells or energy harvesting crack the consumer sports shoe market, for instance (but not necessarily that far off).

Energy harvesting benefits from being new, under-exposed, and promising. Fuel cells are old, over-exposed and problematic. Maybe they will be one of those success stories of the future, where the technology was “ahead of its time.” But that is small consolation today.