The concept of power line communications (PLC) – or broadband over power line (BPL), which now appears to be emerging as the preferred terminology in the USA – refuses to die, and indeed seems to be enjoying renewed vigour. It has always looked like a good idea in principle – with the potential to provide useful revenue streams from existing T&D assets – but the technology and its proponents have suffered several well documented setbacks over the years, with the departure of key players (notably RWE in recent times) and bold claims for the promise of the technology left unfulfilled.

While there are a number of power line communications installations in use around the world, the technology has yet to make any significant commercial impact, and it has yet to find its niche, ie a job it can do more effectively and cheaply than competing communications technologies.

However, in the USA at least, interest in BPL is growing and momentum seems to be building once more. According to a report by the Shpigler Group, Developments in broadband over power lines, there are now nearly 100 trials and early stage commercial deployments underway in North America, compared with “a handful” in 2002. The report projects that “BPL will ramp up to a $2.5 billion worldwide market for equipment in the next five years, with a long-term outlook of serving more than 14 million customers in the US within ten years.” The understandable reaction to such claims is of course to note that we have heard all this before, several times over. But there are a few indications that might justify cautious optimism in the power line communications business.

Ambient Corp, which now sees itself as a leader in the technology, refers to the desperate situation in 2000, immediately after the spectacular demise of Nor.Web, which had promised so much: “At the turn of the new millennium, PLC seemed destined to be forever a good idea that could not be implemented. The inability to bridge the distribution transformer, installation complexities and inadequate economics appeared to be restraints that the industry simply could not overcome.” But, claims Ambient, “The prevailing gloom in 2000 offered little warning of the huge strides that would soon be made in PLC. A number of events converged to rekindle the promise and to convince utilities that PLC could indeed be a major force.”

Crucial has been progress with the technology itself. From Ambient’s point of view one of the decisive events has been successful development of its coupler technology, which, the company claims, also appears to solve the problem of bridging the distribution transformer. Another key development mentioned by Ambient has been “new modem technology developed by DS2 and others” that has achieved “unprecedented data rates.”

There have also been favourable trends on the demand side, not only the vast rise in demand for consumer broadband services, but also in terms of utility requirements, for example providing two-way communication with customers for such purposes as meter reading, demand-side management, real time pricing, outage management, etc.

On top of this is a more favourable regulatory climate in the USA. New rules adopted by the Federal Communications Commission in October clarified what the BPL equipment suppliers and network operators must do to avoid interference with licensed radio services, for example, and therefore help reduce uncertainties for utilities considering investment in the technology. According to Alan Shark, president of the Power Line Communications Association, this rule change “removes any cloud of doubt regarding the viability of commercial BPL deployment”, which, as you’d expect, is overstating the case. But it has provoked the wrath of the radio hams of the USA – a formidable bunch – who see BPL as a major potential pollutant of their part of the radio spectrum, and whose official body, the American Radio Relay League, has emerged as a leading opponent of BPL.

In contrast, according to a joint statement issued by the FCC and the Federal Energy Regulatory Commission these bodies believe that BPL “holds great promise for the American public.” As well as providing “an opportunity to increase the competitive broadband choices that are available to customers” it could help improve grid reliability and efficiency through such means as “self-healing” network capabilities, facilitation of distributed generation and control of energy use. Such BPL services “should be allowed to develop according to market demands with minimal regulation”, says the joint statement.

And it is not only in the USA that we are seeing a more favourable, or at least clearer, regulatory climate develop for power line communications. The Japanese and the Europeans are reported to be drawing up new regulations, for example.

Meanwhile, the potential markets for BPL in developing countries are also receiving attention. It has been pointed out that in such countries the numbers of households connected to the power grid is much higher than those with conventional, copper wire phone line connections and that this could provide an opportunity for BPL as a cost-effective way of equipping such countries with extensive data and voice networks. Here again the question for BPL proponents is whether the technology can do the job better and more cheaply than the alternatives, eg mobile phones.