Renewable Energy and Energy Storage

Relevance of Our Work to the Development of Renewable Energy Sources

A couple of years back I published a pair of lengthy pieces on what was known as the “hydrogen highway”, a term which appears to have passed out of use less than ten years after its coinage. The term referred to a transportation system based upon hydrogen fuel—a system which would presumably supplant the established system, which is, of course, based almost entirely upon fossil fuels.

The vision of the hydrogen highway, articulated long before the term was actually coined, obviously never came to fruition, although plenty of hydrogen fueling stations were built (especially in California) to serve the thousands of anticipated hydrogen fuel cell vehicles that the auto industry would presumably be cranking out by decade’s end. It was an alluring vision and one that was widely accepted among environmentalists and progressive policy analysts because it promised a solution to some of our most pressing economic and environmental problems. I myself was among the early dissenters, and I based my dissent upon an exhaustive examination of open scientific sources, most of which indicated that very significant obstacles lay between the early initiatives and their full realization within a transformed energy regime.

I have no wish to attempt another post mortem here, the first one I produced is still adequate today, but I am in position to add to it since information is available now that was not when I composed my critique five years ago.

There are two cardinal reasons why the vision of the hydrogen highway has not been realized to any extent at all. One is that the fuel cell technology upon which it is based has not proven remotely cost effective. The other is that the vision is built upon another vision, that of a new electrical power grid built upon renewable sources and providing base load electricity at prices below those associated with coal generation. It is on this second factor that I wish to focus now because it has a special bearing on our work.

Many environmentalists and political progressives naively assume that renewable sources are plug-in replacements for fossil fuel or nuclear generators, and that by simply building more wind farms and solar panels we can achieve a zero emissions future and produce plenty of hydrogen by means of electrolysis. That hydrogen would be used to power fuel cell vehicles, and hydrogen production and consumption would undergird the new energy regime.

The problem here is that most renewable sources are intermittent and do not produce electrical outputs that are constant in voltage and frequency. Recent studies have indicated that a 25% contribution from intermittent sources is the maximum that may be allowed while still remaining grid stability. In other words, the path to total renewable energy future is not clear.

Nevertheless, many authorities believe that this 25% maximum could be greatly exceeded if a large enough value of electrical energy could be stored. Indeed with enough storage a grid based entirely upon renewable energy might be possible. The stored energy could simply be released as either high voltage DC or 50 or 60 cycle alternating current, and the transmission and distribution networks could deliver predictable power on a continuous basis.

The problem lies in the cost and capabilities of storage. Most of the few percent of electricity generated which does go into temporary storage is used to pump water up into immense reservoirs. The water is then released through a hydroelectric generator, producing 60 cycle medium or high voltage DC which can be dumped right into the transmission grid.

“Pumped hydro” as it is called, is fairly inexpensive per kilowatt of capacity, but each storage facility is major civil engineering project and the technology is not scalable—in other words, it only makes sense when very large capacities are required. It is also ill suited to most locales for obvious reasons.

The other established storage solutions, including large battery banks, high velocity flywheels, compressed air, and superconducting rings, all have their own shortcomings, chief among them comparatively high cost in every instance, and a number of severe technical limitations, although those vary according to the technology.

I noted these problems in those two articles on the hydrogen highway and I concluded that the vaunted all renewable energy grid was probably not possible.

Unfortunately, a reliance on fossil fuel for the indefinite future is not possible either. The notion of peak oil, once dismissed by most energy industry insiders as a crank theory, is now becoming mainstream, and the government of the United Kingdom recently issued a lengthy position paper supporting the position that the peak of production was immanent, a paper entitled “The Oil Crunch: A wake-up call for the UK economy”. A similar opinion was recently issued by the government of Kuwait, a major oil producing nation.

The uncertainty of future supplies coupled with growing concerns about the effects of increased carbon dioxide in the atmosphere should prompt a rapid transformation to a primary reliance on renewable sources. But how might this be accomplished, given the lack of acceptable storage solutions?

A Fresh Perspective

Since I became involved in energy storage and began to study the various technologies extensively, I have come to believe that massive, flexible low cost storage is possible with existing technology—a complete reversal of my previous position on the matter.

Perhaps rather surprisingly the best solutions involve two dark horses, capacitive storage and flywheels. We are actively engaged in investigating the first area and we are performing theoretical work in the second.

Both are interesting because they are square law devices. The energy density of a capacitor increases by the square of the voltage while that of a flywheel increases by the square of the velocity. No other extant storage technology has this attribute.

Because our innovations regarding these two technologies are proprietary and are not yet patent protected I cannot discuss them but I can say that there are other researchers engaged in similar pursuits and that the likelihood of a breakthrough is high.

If such a breakthrough occurs our energy regime will be transformed and we can begin to retire coal plants and bring carbon dioxide under control. We may also begin to replace internal combustion engines with electric motors because the same storage technologies could provide lengthy operating times for vehicles. In short, an energy storage revolution could change the way we live.