After Maria : Building back Puerto Rico

There’s been lots of talk about Elon Musk sending solar panels and  Powerwall batteries down to Puerto Rico.  This is excellent work — because it keeps the narrative going about distributed power and energy resilience in the face of more intense storms- –which is what the Caribbean is going to have to contend with as the climate becomes increasingly violent.  The phrase ‘global warming’ just doesn’t capture it.  It sounds way too gentle.  That’s not the way the future is going to play out for small islands in the Caribbean and in the Pacific Ocean. It’s going to be much more violent.

Several commentators have stressed that ‘building back better’ should focus on regional minigrid systems powered by solar and wind, coupled with independent power systems on residences and essential infrastructure like hospitals, clinics, hotels, and government buildings.  These systems should be an absolute priority.  This needs forceful government action and mandatory legislation. In fact, all new major construction should have 7-day stand-alone power capability backed up by photovoltaic panels, and for existing buildings over a certain size, retrofits should be mandatory.

What you shouldn’t do?  Rooftop solar that’s grid-tied with no battery storage gives you nothing except the feel-good factor that you are using solar and maybe earning a few dollars through feed-in tariffs.

When the grid crashes, you crash right along with it.

Only if you have batteries and an inverter that switches between AC and DC and back again will you be able to keep your house powered up.

You don’t need solar panels to have this level of autonomy—but you always need batteries. Ironically, in Haiti, because the power goes out almost every day, many homes in Port au Prince and Petionville have a small diesel generator, batteries, and inverter routinely installed.  When the power goes off, the batteries pick up the load.  When they get run down, the generator kicks in. It works.

If you add a few solar panels, you have a decent and very reliable system.  I put 10 100-Watt panels on the roof of my house in Petionville and I never needed to fire up the generator.  The batteries charge up during the day and carry the load through night.  This is the kind of system that should be routinely installed on all the government offices that provide essential services in the aftermath of a destructive hurricane.

But this is not enough.  There are several lessons to learned from the destruction on Dominica and Puerto Rico. It’s not just the collapse of the power transmission and distribution systems. On both islands, that was just an accident waiting to happen.  What is striking is that communications failed, and then there was no water.  How did that happen?

Communications and electrical power are obviously linked.  Cell towers out on the hills are generally powered by diesel generators, and I’m guessing that it wasn’t the gensets that failed—although they would eventually run out of fuel. The one’s in town were powered by the grid. They failed the same instant a tree came crashing down on the local power lines.

The cell towers couldn’t handle a Cat5 storm any better than the electrical grid.  Who writes these specs?  And while we’re on the subject of technical specifications, a few of the offshore wind machines in Puerto Rico lost blades ‘snapped like twigs’.  This is really crappy engineering.

A Cat5 storm will damage many regional and local minigrids.  But not all. And a good percentage of the PV systems on well-built infrastructure will survive. If the cell towers are built to withstand Cat5 wind velocities, you already have the basis of an effective first response.  You have electrical power and you have communications.

In Haiti after the earthquake in 2010, there were two communications service providers: Digicel and Voila.  Digicel crashed: there was no service; Voila managed to keep going at least in the Port au Prince area. The service provided by Voila was a huge godsend to people and families trying to connect.  This is not a criticism of Digicel. It was probably only by chance that Digicel’s service failed and Voila’s managed to keep going.  But communication systems on small islands can no longer be left to chance.

One aspect that hasn’t been talked about is the way PV arrays– the way they are built now—are too easily destroyed by storms and hurricanes.  When hurricane Matthew slammed into Haiti in 2016, it ripped apart the 100 kW PV array that had been installed in the small town of Les Anglais on the south west coast of Haiti, and which was providing electricity to several hundred homes. As photovoltaic systems becomes increasingly essential on small islands vulnerable to hurricanes, engineers are going to have to find ways to make them much tougher and able to withstand extreme weather.

What happened with the water supply in Puerto Rico?  Frankly, I’m not sure.  There has not been much information about the cause of this problem. Lots of pictures of people and families without water—but what exactly is the problem?   If this is just a power failure, it really is scandalous. You mean pumping stations around the island had no diesel generators fueled up and ready to go when they saw Irma coming 5 days beforehand!  Who exactly is in charge here?

The floods are the worst part.  There is nowhere to hide.  You either get out or you get soaked.

But water does drain away to sea on small islands—if the way is clear. City engineers need to make sure that all the drainage canals are clear of debris in advance of the storm—something that certainly never happens in Haiti.

 

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