Blackout in Venezuela: which link was the weakest?

A Russian saying goes, literally, “where it’s thin, it tears.” In his Outlandish Proverbs, published in 1640, George Herbert has a similar one: “The thread breakes, where it is weakest.” Turgenev used it as the title for an early play (1848), translated into French as Le Fil rompt où il est mince – pretty much the same as Herbert’s proverb.

Is this the best explanation for the latest, disastrous blackout in Venezuela? For two decades, the state-controlled operator had underinvested both in generation and in transmission and distribution so something had to give way sooner or later. (“[T]he degradation of the power system is such that we cannot be sure if the fixes are durable,” according to the International Energy Agency.) It’s obvious – but there’s more to the story. There’s a structural risk built into Venezuela’s generation and distribution system: too much of the power is supplied by one hydro plant, and too much of it must come through a single substation to reach users in the capital.

One could argue that Norway depends on hydro generation even more than Venezuela. However, Norway’s generation is highly decentralized, made up of more than 900 power stations, of which the largest have only 10-15% of Guri’s capacity. This still leaves a systemic risk of drought, but it’s rather low based on past experience: if anything, Norway seems to be getting more rain lately.

This said, systemic risks can and should be mitigated. If most of the country relies on one power plant and one distribution station, the last thing you should do is save on maintenance. If you expect a drought… a lot depends on how much time and money you’ve got, obviously, but you can’t simply ignore well-studied, long-term climatic patterns. Gretchen Bakke wrote in May 2016:

After the last bad El Niño drought, in 2010, the government did almost nothing to revamp… It diversified neither its economy nor its electricity supply… the drought [the next one after 2010, starting in 2013] has sapped its power—the latter a particularly galling development, since the weather changes caused by El Niños have been tracked in Latin America since the seventeenth century, and by this point ought to come as no surprise.

Actually, it’s not all obvious that El Niño and the droughts were the principal culprits. Blogger Caracas Gringo, a “Midwest Yankee who ha[d] lived and worked in Latin America over 42 years,” doubted this claim in May 2010. He noted that the government had ordered the power station’s operator to increase “the volume of water flowing through the turbines to generate more hydropower,” which meant “forcing more water through the turbines than is safe.” If you drain a reservoir at a greater rate than usual, you shouldn’t be surprised to see its water level decline even if it keeps raining as usual, to say nothing of drought time.

In April 2016, Roger Andrews, a veteran mining geophysicist and geologist, looked at rainfall levels at five observation stations around Lake Guri and saw no evidence of an extraordinary drought. He attributed the drop in water level to the government’s desperate need to generate more electricity:

Venezuela does not have either the installed capacity or the reliable grid network needed to supply the country’s electricity demand (the retail electricity price in Venezuela in 2014 was only $0.02/kWh) and it’s being forced to drain Lake Guri to get whatever electricity it can.

One reader, a Venezuelan physicist, added some of his own observations and agreed with Andrews’ conclusion. Other commenters were not so sure, but it’s tempting to think of a vicious circle. In a highly centralized system, even a moderate drought can cause a power shortage. Desperately trying to make up for it, the operator would drain the reservoir even more. If the drought goes on, this happens more than once and the water level above the dam falls disastrously fast.

Another approach would be to look at the population growth in the past 20 years, roughly from 22-24 to 31-32 million people, and estimate the associated increase in demand, bearing in mind the abnormally low residential tariffs. I suspect that, even if the economy failed to grow under Chávez and Maduro, growing household demand quickly depleted whatever spare capacity existed in 1999.

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