## Study: frequency of power outages in US stable, but total minutes without power increasing over time

##### 27 August 2015

In the most comprehensive analysis of electricity reliability trends in the United States, researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) and Stanford University have found that, while, on average, the frequency of power outages has not changed in recent years, the total number of minutes customers are without power each year has been increasing over time.

The researchers pinpointed what utilities and their regulators refer to as “major events,” or events generally related to severe weather, as the principal driver for this trend. The finding suggests that increasingly severe weather events are linked to a 5-10% increase in the total number of minutes customers are without power each year, said Berkeley Lab Research Scientist and Stanford PhD candidate, Peter Larsen, the lead author of the report.

The researchers analyzed reports for a large cross-section of utilities representing nearly 70% of US electricity customers spanning 13 years from 2000 to 2012.

Although a 2013 White House report noted that major power outages and severe weather events are increasing, this study is the first of its kind to use econometric analysis techniques to statistically correlate these events with electricity reliability. Most studies of reliability have relied on information that reflects only the largest power outages. Yet, over the course of any given year, the largest events typically account for no more than 10% of all power outages. This study, by relying on information for all power outages, both large and small, conclusively identifies a trend that is linked directly to these larger events.

We find statistically significant correlations between the average number of power interruptions experienced annually by a customer and a number of explanatory variables including wind speed, precipitation, lightning strikes, and the number of customers per line mile. We also find statistically significant correlations between the average total duration of power interruptions experienced annually by a customer and wind speed, precipitation, cooling degree‐days, the percentage share of underground transmission and distribution lines. In addition, we find a statistically significant trend in the duration of power interruptions over time—especially when major events are included. This finding suggests that increased severity of major events over time has been the principal contributor to the observed trend.

—“Assessing Changes in the Reliability of the US Electric Power System”

One surprise was that the study did not find a consistent link between reliability and utility transmission and distribution (T&D) expenditures.

This work was funded by the Office of Electricity Delivery and Energy Reliability, National Electricity Delivery Division of the US Department of Energy. Other co-authors were Kristina H. LaCommare of Berkeley Lab and James L. Sweeney of Stanford.

Like with streets, roads, highways, bridges and railroads; local electricity distribution networks maintenance have been neglected for many years causing more and more LONGER power failures.

In many places, networks overhaul and production units refurbishing have been postphoned to the limits. This will translate by more and more power failures.

Meanwhile, the OIL Industries are asking for an extra $500B in subsidies (on top of the very high OIL wars cost) to deal with lower OIL prices. What oil subsidies? Maybe in Russia, not here in the US. Oil & Gaz is financing the government(s) at the rate of$XXXB/year in Russia but it is the other way around in USA?

Please check the cost of OIL wars (supported by USA's tax payers) in the last 20+ years? Phase two (2) has started against ISIL and may cost even more.

Trust Harvey to drag irrelevancies into an issue about electric power outages.

My power has been particularly unreliable of late, sometimes having several short interruptions per day.  The generators themselves have nothing to do with it:  a major storm a few weeks ago partially broke or bent many trees, which are now in position to briefly touch and short power lines when the wind is up.  Until these trees are found and trimmed back the problem will continue.

That's what I met by overly relaxed local distribution network maintenance. Over 400,000 customers lost power in the Vancouver Area in the last 2 days windy days for the same reason.

Buried cables (that's what we have in our immediate local area) could reduce this problem but cost 6X to 8X more to install.

Rural areas can't afford buried cables.  The last mile of the feeder that serves me (I'm at the extreme end) has perhaps 15 direct customers, with a few more on a branch that is probably half a mile total.  What will happen is that the data loggers will indicate where the problems are, the tree crews will trim the problem trees back and things will go back to normal.

Strong winds coupled with heavy rain, ice rain and/or heavy snow falls very often overturn adjacent trees and will break electric and communication cables.

This will happen more and more often as the climate changes and we get more bad weather.

The secure way out of this problem is to bury cables as we bury water, sewage and NG pipes. Areas where this is done do not have power shut down and do not have all those ugly poles with cables.

Better built high voltage power lines will (and do) resist bad weather and operate with great success for many years without failures.

The problem isn't the actual HV lines.  The problem is with the 13 kV and 7 kV distribution lines between the substations and the pole pigs.  Those lines are along tree-lined roads, not on dedicated rights-of-way.  Trees will fall on them, it's the price of living with the beauty of trees.

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