Technically, Broadband over Power Lines (BPL) always seemed to me the electrical equivalent to pushing rope. The San Diego Gas & Electric experiment on the two blocks that surrounded my home in 2006 involved an impossibly expensive array of wireless and wired transceivers and multiple high and low voltage couplers. All that gear was required to get the VHF signal a block or two at the most before it faded and required a repeater and more coupling and decoupling gear. See, VHF doesn’t travel well down an unbalanced open wire. The HF signals used in an earlier pilot didn’t do much better.
The poor closed transmission qualities of the power lines meant they radiated most of their energy. While the industry worked hard to protect incumbent users of the spectrum–read ham radio and land mobile emergency services–the lines radiate so much that there really is no way for them to reliably comply with the original FCC Part 15 rules unless amended to specifically excuse the industry. In local trials, we measured little radiation on frequencies used by hams and the state. The worst emissions were produced on parts of the AM band by one of the power supplies used for a BPL modem. SDG&E involved hams, emergency communications users, and me as representative of broadcasters in an effort to monitor their BPL experiments, and that was a commendable move. Nonetheless, they energized power lines and radiated RF.
BPL has reminded me of the huge coal plant 16 miles from the Grand Canyon. The haze harmed the view of the canyon from the day it opened, but why should we purposefully foul the air anywhere if it isn’t necessary? Your government backed an inherently harmful technology when it could just as easily require scrubbers or not allow the burning of coal for power at all. It’s legalized pollution.
Follow the Money
Terry Snow, local engineering coordinator for SDG&E, told me they ended local BPL trials in mid-2007 and removed the equipment soon thereafter. The utility determined that BPL simply isn’t economically feasible.
Why is this? BPL as an internet service alternative for consumers, as envisioned by non-technical regulators, doesn’t pencil out. All the stuff required to modulate power lines designed for 60 Hz service simply is too expensive to supply a few homes in a neighborhood. The FCC said they wanted a competitive internet service for consumers to keep the price down, but they assumed the science would work economically. It hasn’t.
So how do utilities with BPL now, like those in Manassas, Virginia, make it work? First, you have to ignore those who complain about spectrum interference. The American Radio Relay League, the ham radio lobby, has battled the FCC for years to get them to enforce their own interference rules. Manassas hams are screaming for relief from the blanket of noise.
Second, BPL isn’t about internet service for you and me–it’s about advanced metering infrastructure (AMI). The derivative of AMR, or Automatic Meter Reading, is the technology that allows utilities to measure and control how much power you use at what times of the day. In fact, Terry Snow says, the California PUC specifically forbade them from selling internet service to the public.
You see, companies like those in Manassas can’t afford BPL unless it is subsidized by rate increases for all electric power users, and the CPUC said they could use the rate increase for AMI. But they aren’t allowed to charge all consumers for a service that would benefit only those few consumers willing to pay an additional premium.
Power generating plants and lines are not only very expensive to install, nobody wants them in their neighborhood. And once the systems are in, the power companies don’t want to have to rebuild them because you are using more power for your new spa or third TV. Peak power is the problem. Utilities are very good at providing power for your normal needs day after day. But when it gets hot around here, they can just barely supply enough juice at 4 PM.
The utilities have asked us to conserve power, but nothing works as well as good, old-fashioned supply and demand. If the electric company charges, say, 10 times as much for power delivered at 4 PM on a hot day than they do for power delivered at 4 AM, people will be more mindful of their air conditioning settings and run the dishwasher when demand and rates are lower. It makes sense if you believe in classical capitalism. But remember that this is a regulated monopoly. Utilities like demand pricing because they can profit from figuring the rates in such a way that the median charge for energy increases.
It turns out that the cost of implementing AMI for the general public is big. So big, the utility group UCAN says the best case scenario is for a 25-year payback, and worst-case has the costs just never paid off. UCAN suggests for peak demand control a series of measures from conservation incentives to large-user controls to voluntary peak cutoff systems. I had a radio subcarrier receiver in an apartment in Utah that the utility could use to cutoff the air conditioner if peak demand in the neighborhood grew too high. At Bay City TV, we participate in a peak generation program, running a generator and taking our facility off-line by request when demand gets dangerously high.
SDG&E and other utilities continue to explore peak demand controls and AMI, but the definitive method of measuring and controlling electrical power delivery hasn’t been determined or implemented yet.