Just like the articles about how car batteries that are idle at home can be used to power shortfalls in grid supply I have one pressing question.

What happens if you need all that power that should have been in the battery but is now reduced because it is been syphoned back into the grid to make up for a shortfall?

Nobody appears to be able to address this. A UPS is generally sized for a specific load and runtime. That needs to be available at all times to cover an event where the power is lost. What is the use of a UPS that has the runtime reduced because it has been exporting power to boil kettles in the advert break or because the wind is not blowing enough?

You can see the conversation now

CEO: We specced and paid for UPS capacity to cover a 2 hour outage, why did it fail after 80 minutes?

Eng: Because Clive signed up to exporting our "excess" to the grid - it's only supposed to use about 10%, but turns out the cells have cycled a lot more than we expected.

What happens if you need all that power that should have been in the battery

I suppose the answer is to make sure that the battery is always on charge from the mains to keep it topped up

I could see where the backup gensets could be used for helping during a brown out in the grid but I can't see how this would work for UPS as they only have short run times to give the genset time to start. This also has the issue that the UPS and gensets are sized for the load and if a brown out happens or worse a total power loss then the data center will want all the available power.

This does have the feel of a report done by people who don't live in the real world

This does have the feel of a report done by people who don't live in the real world have some proposition they want to sell to the bean-counters. The mention of "cost centre" is a give-away.

What this shows is desperate people clutching at increasingly feeble straws.

[1]Gridwatch suggests that electricity demand is at ~42GW load at peak.

In terms of generating capacity we have:-

30GW of gas turbines

7GW of nuclear (rarely all online at the same time due to maintenance and refuelling)

4GW of (mostly mothballed) coal

3GW of coal plants converted to burn trees

= 44GW.

So bluntly, excluding imports and wind we have just enough power generation to survive one nuclear plant doing maintenance or refuelling and then we have a blackout.

We do of course have [2]25GW worth of wind turbines , which should be supplying over half of our energy needs. Unfortunately, the graph showing the feed in for the last year on gridwatch shows those actually generated about 5GW worth of power for something like half to two thirds of the year, and 10GW in the remainder.

Which means that the prevailing energy policy has completely and utterly failed at generating electricity (although it has generated good money for jobs for the boys the green industry by increasing the price of the power that is actually generated) and we are now left staring at the probability of blackouts as old capacity with actual power outputs is decommissioned and replaced with replacement wind turbines with "up to" power outputs that everybody but the terminally delusional knows will never actually be reached.

In terms of lost capacity, Dungerness B (1.3GW) closed last year, Hunterston B (1.2GW) has just started decommissioning , Heysham 1 (1.3GW) goes in 2024, Hinkley point B (1.3GW) goes in 2024 and we are committed to decommissioning coal by 2025 (3GW) which is 8.1GW of generating capacity gone in the next 3 years with nowt but wind turbines and prayer (to mother nature that the wind will blow continually) as replacements.

Hinkley point C might come online in 2026 if it's on schedule with 3.2GW worth of juice, meaning we'll be down 4.9GW worth of capacity.

And of course, people are being asked to decommission gas boilers for electric heat pumps and go with electric cars, so demand is going to increase over this time period.

How do you deal with that? Well, this suggests that asking everybody in the country with backup gensets UPS's to feed in supply when the grid is desperate is the next plan.

[1] http://gridwatch.templar.co.uk/

[2] https://www.statista.com/statistics/421861/wind-power-capacity-in-the-united-kingdom/

how come the grid operators don't invest in some batteries themselves?

>>how come the grid operators don't invest in some batteries themselves?

They do (in Austrailia, at least)

In my experience the UPS/switchgear is one of the things most likely to result in you reaching for the torches due to a dark and silent data hall. I fear adding yet more complexity to a UPS isn't going to improve matters.

Provided it means there will always be enough power for the UPS to do its main job.

Octopus Energy in the UK have already teamed up with Tesla to provide a VPP ( [1]Tesla Energy Plan ), with consumers getting charged a much lower rate for electricity for joining the program, so it looks as if everything is in place to make this happen.

[1] https://octopus.energy/tesla-energy-plan-faq/

If I have PV and a battery bank at my house then I would expect to see a much larger saving than that page is suggesting.

With the right setup you shouldn't need the grid at all, trouble is this would not work every type of property.

As above not only does investing in a UPS mean you expect to have a runtime normally specified based on cost i.e. 20 minutes costs X and 40 minutes X*3, big bosses aren't going to be keen on the extra risk.

But if you are charging/discharging then you are using the limited number of battery cycles and X/2 is probably the cost of replacing the batteries.

Both costs will need to be factored into any payment.

a) What's in it for the DC operators ? I certainly wouldn't want to turn around to all the customers who are paying for UPS backed feeds and saying "Oops we gave all the power back to the grid"

b) I was always under the impression that there was less than an hour (if not less than 15 mins) of power in the batteries. They are there to smooth the load before the generators kick in to provide the power after all.

I know a number DC operators have heaters (typically water radiators) on their generators so they can provide load sooner

"Instead, about 80 per cent of respondents estimated that between 10 and 50 per cent of the capacity of the battery systems deployed in their data centre today is excess..."

First of all, 10% is not a lot of margin. Battery capacity varies with temperature and age and most battery banks at DCs are designed to last only long enough to start generators; 10% of that time is not much. 50%, on the other hand, is a lot of excess margin, but either it was specified that way for good reason (to survive a 99th percentile generator startup time instead of 95th, say) or it should never have been designed that way in the first place and is a waste of money. In short, there should not be "excess capacity" in DC UPS battery banks.

"According to Schneider Electric, these changes have been made possible by newer UPS systems using lithium-ion battery technology rather than the valve regulated lead-acid (VRLA) batteries traditionally used."

This is both true and a lie. Flooded lead-acid (same chemistry, different maintenance design) is no more expensive than VRLA but with proper maintenance -- which can be partially automated -- have design lifetimes up to 5000 charging cycles. There are two basic parameters that affect lead-acid battery lifetime at a given depth of discharge: plate thickness and electrolyte maintenance. VRLA batteries "wear out" because they lose electrolyte during charging and it's not replaced. The valves regulate this loss but do not eliminate it. Because of this limitation, they are also designed with thin plates because there is no point in having plates that will outlast the electrolyte. Thinner plates also allow greater current to be supplied by the cell, which is important for applications like starting an engine, but for UPS applications even very thick plates can supply more than adequate current. Flooded batteries have no valves but are designed to have water added periodically to maintain proper electrolyte levels. They can be, and are, designed for a wide range of points on the curve of cost and max current vs. lifetime and depth of discharge. This is the main distinction in whether the batteries you see at the auto shop are being sold as "starter", "deep-cycle marine", "off-grid power", etc. Installing thin-plate VRLA batteries in a stationary application like a DC where weight poses no problem and a staff is always on site to perform periodic maintenance is insane. A DC UPS battery bank will have a very small number of very deep discharge cycles and will otherwise be maintained at the float voltage, which means electrolyte loss will be minimal. Whether FLA or VRLA, such a bank should have a lifetime of 7-10 years minimum and possibly longer. There are many batteries on the market today with these attributes and warranties of 7 years or more. Lithium-ion is much lighter and more compact -- important for mobile applications but unimportant for stationary use -- and is maintenance-free, but it is also 3-10x as expensive at a given capacity point and comes with a small risk of causing a fire that is all but impossible to extinguish. The only reason to push for lithium chemistries in an application like a DC is because you're selling ignorance. If your goal is to market your DC to people who think lead-acid is "obsolete" and lithium the new hotness, by all means. Or if you're a manufacturer of lithium-based batteries and can convince a DC manager of that on the golf course, again bully for you. Otherwise it's a joke.

'"In addition to voltage and frequency regulation plus power back-up, a data centre UPS can be used for peak shaving, demand response, and even to send excess power into the utility grid for profit," he said.'

Yes, and the equipment suppliers listed have been selling electrical equipment for many years that offers all of those features and support a wide range of battery chemistries, voltages, and capacities. All of this has been on the market for over 20 years and has been widely-deployed with mostly FLA or VRLA battery banks. This feels like nothing but a marketing push: talk up "renewable energy grid integration" and "new frontiers opened by lithium-ion batteries" because those things sound sexy and people read about them in newspapers; maybe it'll sell more electrical gear. In fact there's nothing new about any of this; you could (and many have) built systems that do all of this in a dizzying array of scales, applications, prime power sources, and grid integration or lack thereof. There's no good reason to add these features to a DC UPS unless the DC is powered mainly by local generating sources rather than the grid, in which case the UPS is not really a UPS any longer but a core part of the electrical supply system with very different design goals.

https://fgw.ddnss.de/StromSpeicher.html

An online translator can give you an English version.

Chemical Batteries are in the order of 100x to 1000x too expensive to store a nation's electricity for a month. Also, they wear down in a few years, unlike a concrete construction, which can last 100 years, if properly done.