By Planning Engineer
Considerable efforts are being undertaken to restore power in Puerto Rico. Most coverage has been pessimistic focusing on challenging logistics and contentious issues with very little upbeat coverage on progress so far. There is one major exception to this trend, the efforts of Elon Musk and Tesla have enjoyed glowing coverage.
We know that Tesla has recently installed a combined solar panels and battery system in the parking lot of the Hospital del Nino in San Juan Puerto Rico. Beyond that, reputable information gets kind of sketchy. While there are many sources ranging from positive to gushing, the provided details as regards this project are often contradictory.
NPR headlines proclaim, “Tesla Turns Power Back On At Children’s Hospital In Puerto Rico”. Similar headlines appear in EcoWatch, Global Citizen, Huffington Post, ThinkProgress and other “news” sources.
Reading most sources it appears that the Tesla installation restored service to an outaged, dark hospital. However, ABC news reports that,
A children’s hospital in Puerto Rico that was forced to run off generators and ration diesel fuel in the wake of Hurricane Maria now has a solar power system that will supply all of its electricity needs…. A hospital spokesperson told Primera Hora last month that they were forced to ration diesel fuel and take other measures to ensure a constant flow of electricity.
If ABC is correct Tesla should more accurately be credited with increasing reliability and improving fuel supply, rather than restoring service.
Does the Solar Facility Allow Full Service?
The LA times reported that:
Tesla Chief Executive Elon Musk said on Instagram that the hospital needed more power than a typical roof installation could provide, and that this system would allow it to operate completely off the grid.
However Popular Mechanics notes,
The solar farm can keep the hospital running almost all the time” and adds “The hospital does have backup diesel generators in case they run out of solar power, but now they don’t have to depend on those generators exclusively
Since there is so much misinformation at there and very little that appears solid, it’s not really clear whether the diesels are now supplementing the solar/battery configuration or if it’s the reverse.
Knowing the size of the solar/battery facility would help as well as understanding the load needs of the hospital. According to tweets from CBS News correspondent David Begnaud, the system provides 200 kWh of solar energy and 500 kWH of battery storage. Others quote him as saying they provide 200 kilowatts of solar power and 500 kilowatts of storage. There is a crucial difference between kw (kilowatts) and KWH (kilowatt hours). It seems most likely that the solar output should be expressed in KW and the storage capability in KWH. If that’s the case the numbers would mean that in addition to the 200 KW provided by the solar cells, when the sun is shining you might be able withdraw an additional 100 KW from the battery for approximately 5 hours. Alternatively the battery draw could be 50 KW for ten hours. This is not a lot of energy, but then the hospital appears to be quite small.
More Projects Coming?
Elon Musk’s much repeated tweet is that this is “first of many solar+storage projects going live,”. Karen Graham writes in Digital Journal that, “Tesla finishes first of many solar projects in Puerto Rico”. Popular Mechanics is more subdued reporting that “There are also signs that this will become one of the first of several”. Checks by me and Popular Mechanics turn up no details or descriptions that have been made available concerning what other projects might be on the docket.
Will the Solar Facility remain?
A translation of an article by Antoio R. Gomez notes that Mario Lopez, the hospitals executive director
“…explained that the donation of Tesla is free of charge and indefinitely, and until the energy crisis in the country is resolved. After that, he said, the parties would negotiate an agreement for the permanent acquisition of the system, for which they will require the contribution of the foundations and individuals who support or want to financially support the Hospital.”
A look at Google Maps suggests that the question of where cars might park likely needs to be addressed first. The quote above hints that funding the permanent acquisition of the equipment would exceed the cost of normal electrical service. Perhaps it would be sold at a deeply discounted cost and disassembling and removing the equipment will be quite costly.
Publicity Stunt, Promotional Venture or Practical Solution?
This is really the important question. Although there appears to be a rush to judgment by many that this represents a practical solution, at this point barring further information it should be an open question. No cost data is available. A great deal or resources and effort was expended to set up this solar/battery facility in the parking lot of a small children’s hospital. To the extent the equipment is removed later and shipped elsewhere the economics of this demonstration will appear much more dismal and impractical.
Tesla is seeing payback from their efforts through the publicity provided by Musk’s tweets and this “feel good” story going viral. But to generalize from this situation to others, one must remove those benefits and ask “does this solution make engineering sense on its own?”
If this solution is only better because some deep pockets organization can subsidize it because of publicity, we should not cheer this as a demonstration of the practically of such systems. Many questions must be asked first, for example could the hospital, a governmental entity or other benefactor have better served the children by procuring and providing temporary additional fuel resources for the existing generators there? Could extra resources directed at mobilizing line repair efforts provided more bang for the buck? Is this just a case where a lot of effort produced an isolated benefit with costs all out of proportion? Answers to these questions may support solar/battery systems such as this or instead suggest we are better off expending efforts elsewhere.
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