Microgrid Keeps the Power Local, Cheap, and Reliable | Hacker News Reader

Microgrid Keeps the Power Local, Cheap, and Reliable

technologyreview.com

22 pointsiProject11 comments

Diesel generators and massive arrays of toxic lead acid batteries, which have a lifespan of at most 5 years, are not "green energy" and I'm a bit tired of all these articles in the press by persons claiming to be "alternative energy editors" and such who are promoting them as if they are because it's very clear they are not really advocating for truly sustainable energy. Even adding in the solar panels, they have a lifespan of 25 years due to eventual UV breakdown of the components, and the vast energy required to refine and purify the silicon wafers and extract the rare earth elements used in the construction eliminates the advantage of the technology as either sustainable or green.

The wind turbines are good, but have widely variable output, are only sensible in a small number of areas with a lot of wind, and again, require batteries for 24/7 secure energy such as at this jail facility, again eliminating the advantages that would enable it to be reasonably classified as green or sustainable.

With this particular jail, there is less than average wind and more than average overcast days in Dublin California where the jail is located, making these poorly matched alternative energy choices for this area, and which only ensure these systems are even less effective, and making clear that during power outages the diesel generator and batteries are going to be the real source of power.

The mention of air conditioning being powered by solar cells is particularly evidence of the bizarre reasoning of the article, which I leave to the reader to ponder why this is so. One may wish to start by asking how many residential installations are able to power air conditioners directly from photovoltaic cell arrays.

This is a boondoggle to be sure, but does not mean energy reduction shouldn't be pursued. For some prisons in desert areas such as Arizona, much energy could be saved by switching from air conditioners (if they use them; not all prisons do) to passive evaporation towers such as have been used in the middle east and africa for hundreds of years. Dublin California is not a candidate for this technology with average daily humidity of 76.24%, close to the national average of 77.52%, but many prisons, schools, offices and houses are.

Please provide citations for your assertion that solar panels require vast amounts of energy to produce.

When I looked into the question a few years ago, the best sourced estimates I could find put the EROI at less than two years.

…it makes sense to use the system's ability to temporarily decrease power consumption at the jail for things like the air-conditioning or lighting to create more excess power to sell to the grid.

Nothing says "for profit penal system" like turning off the environmental support systems when you can make a lot of money diverting the power for sale.

The picture of the bank of SLA batteries just reminds me how crappy energy storage still is; Those are just small improvements of what would have been used the year I was born.

They say they save $100,000 per year, but what was the cost to implement this, and how much does the battery maintenance cost?

This page:

http://www.acgov.org/government/news/smartgrid.htm

Says $11.7 million. But that is the project cost, not the additional cost of using this system to provide backup power to the jail.

So they can save those $100,000 per year after 100 years. Good luck with that.

It depends on the characteristics of the alternatives that they had. Given that the prison is designed to house 4,000 people, I imagine the cheaper alternatives were still in the millions of dollars.

The cheap alternative here as far as power is concerned is grid electricity and have natural gas turbines for electrical backup. Blackouts never last more than a day in this area, and very rarely that long, so being able to run the air conditioning is not important, you need to run lights, security cameras, and the door locks.

However much they are generating with solar cells it's not even a fraction as much as they would save in switching to a geothermal heatpump system for the heating and cooling needs, which would have been a fraction of the cost of the solar system, and a minute fraction of the ongoing costs including battery replacement.

This is about certain people getting contracts to sell stuff to the government. Anyone competent who is really interested in a good solution wouldn't have built this system.

117 years, but only as long as we completely ignore that all the batteries have to be replaced every 5 years, the solar cells every 20 years, and the diesel generators have to be continually maintained and swapped out with new fuel - if you just store diesel passively long term, even with fuel stabilizers, it goes bad, so use it or lose it with that.

We need a Zed-P-M!

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