Fuel-cell, microturbine, and flywheel products are taking off, but what will be their environmental impact? Engineers need to know. Alternative energy is a two-way street.
The new product arrivals focus on three basic themes: Green technology, the reduced cost of ownership as compared to lead-acid batteries, and the end of the lead-acid battery itself. The products appear to solve various cost issues and the local pollution problem, but what's it mean globally? The flood of e-mails I've received following MGE's announcement of a hydrogen based backup source for UPSes (EE Times, October 20th, p. 105) tells me that engineers are rightfully confused. We need some basic answers from the experts, except they don't have a firm grasp, either.
The questions pouring in range from how MGE's system is being accepted in field trials to how long lead-acid batteries will exist as a viable product. In general, editors aren't privy to most internal info, nor in most cases are we experts. What seems clear, however, is that the death of traditional battery designs has been greatly exaggerated. Beyond that, readers share one basic thought: You need fossil fuels to extract hydrogen. The mail further demonstrates our readers' expertise in thermodynamics, exemplified by a bunch of proofs pro and con for alternative energy. But in thermodynamics, one has to define the total system. Unfortunately, many of the proofs ignore the fact that "irreversible" does not mean that a system can't be returned to its original state, but that the system plus its environment cannot be restored. And it's the universal environment we need to know about.
It's a tough subject, best left to an interdisciplinary task force. As a young guy at Bell Labs in the 60s, I remember several hotshot engineers attempting to redress the energy balance for a situation where the entire land area of Arizona was populated by solar cells to charge batteries. In the end, the issue gravitated around the related rates of two exponential equations.
One described solar input directly intercepted by the solar cells, and the other the resulting decrease in land (surface) temperature owing to less solar input and the ramifications of that. I don't recall if the modeling was correct but, more important, it was when I first actually realized you don't get something for nothing. Alternative power seems destined to be part of our lives, but design engineers need the pros to step in and explain exactly how it all comes together.
Vincent Biancomano covers power products for eeProductCenter. Contact him at firstname.lastname@example.org.