How poor is the US electric grid?

And what must be done to ensure the future security of supply?

Experts seem to agree on the fact that the current U.S. electric grid has room for improvement. The rise in the number of blackouts in the US over the last twelve years clearly demonstrates this fact (see my post of 2 June.) However, opinions differ on how dramatic the situation really is.

In an opinion article in the Energy Bulletin, Gail Tverberg paints a very dark picture. If a major upgrade of the grid is not undertaken, it will be necessary to seriously downscale expectations concerning the free trade of electric power, renewable energy, and plug-in vehicles. She even foresees a situation in which some areas of the country may be forced into planned blackouts. In my experience, things are rarely as bad as they may seem at first, but consider this an interesting thought experiment from her pessimistic point of view. It reminds us of the fact that we should not take the high reliability of electric supply for granted, neither in the US, Europe, nor any developed region.

Why today’s network no longer suffices

The main grid problems Tverberg mentions are similar to those summed up in a paper by the Carnegie Mellon Electricity Industry Centre. Built in the sixties, a large part of the network is approaching end-of-life. Moreover, it suffers from an increasing number of long-distance transmissions due to the free trade of electric power, inadequate investment in transmission system infrastructure due to the fractured responsibility, and a lack of system-wide management of the system for the same reason.

Tverberg also points out a few additional issues. She refers to a report by Stow Walker of Cambridge Energy Research Associates stating that due to the development of wind energy in Texas, the so-called spare capacity of the grid has now been depleted and new transmission capacity is needed to accommodate more wind farms. Even with the still modest current penetration of wind energy in Texas (2% of the total annual electricity in 2007), near-rolling blackouts have been reported.

According to Tverberg, the lack of investment is not only occurring at the transmission side of the electric systems, but also at the generation side. She states that there is 'little incentive to add generating capacity … as long as there is a possibility of purchasing power elsewhere.' In other words, as long as power companies can buy the cheapest electricity available elsewhere and make unlimited use of the public transmission grid to transport it to other regions.

The consequences could be far-reaching

Tverberg sees dramatic consequences of continuing business-as-usual. She predicts a further increase in the frequency of blackouts, particularly in the North-Eastern US and Southern California regions. Since the development time for new transmission lines is longer than for new built generation capacity, the stress on the grid will gradually increase. On the longer term, this might lead to the return of the situation in the past when local electric utilities had a monopoly to serve particular areas. In addition, Tverberg adds that 'If some areas do not have enough locally-generated power, they may be forced to have planned blackouts, perhaps for several hours a day.'

This vision is a very pessimistic one, and many things have to happen before it occurs. Nonetheless, we should take it as a reminder that the current reliability of supply did not magically appear out of thin air. In order to ensure future reliability of supply, governments must create sensible policies and structures that ensure sufficient infrastructure investment and best-practice network management.

Step-by-step changes or large-scale building projects?

Tverberg believes that only a radical transformation can fundamentally improve the system. She proposes three large-scale developments:

• An extra high voltage back-bone transmission network, overlaying the current transmission grid
• A smart distribution grid, with transformers and meters capable of digital two-way communication
• A real-time transmission monitoring system enabling quicker reaction to sudden shifts in power needs or power availability

This call for large-scale developments is in contrast with the Carnegie Mellon Electricity Industry Centre paper, in which the authors advocate step-by-step improvements. They stress that building new lines is not the only way of enhancing the availability of the grid. Some modest measures can already make an immediate and significant difference. These include such things as composite conductors to increase thermal ratings of lines and phase-shifting transformers to relieve bottleneck constraints. Examples in Europe also show that a positive impulse can come from a unified power trading market in which generation and transmission capacity is auctioned jointly on a day-ahead market. It causes prices between the regions converge and potentially enables optimal use of cross-border transmission capacity.

A combination of both visions

Investing in new transmission capacity and the development of smart grids are probably a requisite if we are to combine our ambitions of economic development with carbon emission reduction. This has been demonstrated once again by a Danish study investigating the possible evolution to a 50% distributed generation. The study shows that this ambition would require a strong re-enforcement of the transmission capacity and the development of smart grid systems. However, such large-scale developments take decades, and in the meantime, a great deal can be achieved by the right small-scale measures.

References

• Article 'The US electric grid: will it be our undoing?' on Energy Bulletin
• Article 'State almost saw rolling blackouts Tuesday night' on DallasNews.com
• Blog post 'Increasing frequency of black-outs in the US'
• Paper 'Trends in the History of Large Blackouts in the United States' by The Carnegie Mellon Electricity Industry Center
• Article 'Lines lacking to transmit wind energy' on USAToday
• Blog post 'From 20 to 50 % in the Danish Power System'