One thing Hurricane Maria has taught us is what a hollow shell
PREPA is. The thousand plus megawatts of generation (Palo Seco plus San Juan
plus various gas turbines) should supply the metro area. An almost criminal
lack of maintenance makes those plants unavailable. A million people sit in the
dark because of this neglect.
It is time to take some eggs out of the PREPA basket. We
don’t need a few big plants located far from the point of use. We need hundreds
or thousands of small plants generating electricity where it’s needed.
It’s time for massive cogeneration.
Any generator plant, whether a large plant like Aguirre or a
5 KW home plant, converts about 30-40% of the energy input to electricity out.
The rest is wasted mainly in the exhaust and, in the case of a gasoline or diesel
plant, the radiator.
A cogeneration plant generates electricity normally but
captures the waste heat and puts it to use. It can make steam or hot water if
needed. More usefully in Puerto Rico, the waste heat can power an absorption
chiller (Wikipedia can explain) to make chilled water for air conditioning. Cogeneration
plants operate at 60 to 70% efficiency or more. The high efficiency makes even
small, 50KW+ cogeneration plants technically and economically feasible.
Cogeneration efficiency is also boosted by the lack of
transformers. Transmission distances, and losses, are measured in feet rather
than miles.
Even better, they help the environment. They do this by
using a higher quality fuel, diesel instead of bunker C or coal. Higher
efficiencies mean they use less of it. A double win.
In Puerto Rico we’ve rightly learned not to trust PREPA. That’s
why so many businesses and restaurants have standby generators. Many could be
converted to cogeneration turning the generator from a cost to a profit.
Cogenerators still need to be connected to PREPA for backup
power when their plant is shut down for maintenance or fails. This works both
ways and can benefit both cogenerator and PREPA.
My favorite restaurant, Lolita’s in Fajardo, has a 150KW standby
generator to allow normal operation during power outages. If they used the
waste heat for air conditioning, they may only need 100KW for the rest of the
business.
That gives them 50KW they could sell back to PREPA. That
adds 50KW of reliable power to PREPA’s capacity. Modern dispatching technology
takes care of power flows in both directions depending on whether the
restaurant or PREPA needs it at a given moment.
Many small distributed plants
will be more reliable in aggregate than a few massive central plants.
Cogeneration is a proven technology that has been in wide
use for more than a century.
PREPA has resisted it in the past. They need to be
brought into the 21st century.
Maybe it’s time for President Bush’s “Thousand points of
light” in Puerto Rico.
