Very long run of LV Cabling

Hi Broadgage, yes my initial thoughts were to connect to a UPS system for on demand lighting and power and the generator only providing top ups to the battery bank, the problem I found is that most batteries simply aren’t designed to run under normal continuous use daily and the constant charging and discharging of the batteries would end up with continuous replacement and maintenance Unfortunately

Cheers 

Most UPS units are indeed intended for short term use. Two alternatives exist.

Firstly, use a standard type but fitted with large external deep cycle batteries. This will give a greatly extended run time. Remember that the inverter in the unit was probably only intended for very short term operation and may be killed by prolonged operation. Restrict the load to less than half of that intended to avoid this.  Secondly be aware that the battery connections may not be isolated from the mains input and must therefore be treated with the same care as any other mains voltage connections.

Alternatively use not a ready made UPS but a power inverter intended for an off grid home. Select one with a generator input and automatic transfer.

Look.

Another £1.5 Billion in tax then. It's a good thing I no longer have any generators, this would be disastrous as an additional business cost. The idea that one can “change to less polluting” fuel is idiotic, they are all less efficient than diesel and the new engines would cost literally millions of pounds. It is not at all clear what fuel could be used for replacement, even biofuels have the same silly level of tax. Perhaps they think that a few portable windmills are suitable for filmmaking, television, or events. Good luck with that Boris. Clearly, the fools are well in charge of the asylum!

Red diesel fuel is often used very wastefully because it is so cheap.

The requirement to use the more expensive white diesel for some applications will probably reduce consumption.

Construction site equipment is often left idling all day to save the trouble of starting it.

And at present even white diesel is cheaper than the market price for grid electricity. White diesel is currently up to about £1-60 a liter. A reasonably efficient modern diesel generator produces about 4 kwh per liter of fuel consumed. So the fuel cost is about 40 pence a unit.

The open market price for grid supplied electricity is about 60 pence a unit, not the !capped" domestic rate or existing fixed price deals, but the market price for new customers or those transferred from bust retailers. 

Why is it that the Government thinks that energy use can virtually stop? Typically a large festival needs 2 500 kVA generators per stage, one as running backup in case of problems. I, therefore, need 200 kVA X 18 hours of batteries per day that can manage a peak discharge of 500 kW. This is 9 MWhr / day and some festivals last 5 or more days. I would need 2 sets of inverters and some backup batteries. From Tesla, such a battery would cost at least 2 million pounds for each day, and a pile of lorries rather than one to move it. It is therefore fairly clear that this measure is simply to raise taxes from the entertainment industry (again), and not about anything else. BTW such large batteries would be very dangerous being transported, an accident could start a pretty big and dangerous fire, much worse than a diesel tanker accident which would probably not catch fire and contains more than 10 times as much energy. Imagine a feature film working for 2 months. Less power but much longer. Or a television show like Wimbledon. Mains power may be available in some places, but generators are the mainstay for all this work, partly because they cost less and partly because of the convenience of turning up and power is immediately available.

For a large pop festival I agree that use of diesel generators will continue. The organisers or promoters will simply have to pay full price for the diesel fuel consumed.

A temporary high capacity connection to the grid would be preferable if available.

Maybe the government would prefer people to switch to LPG-powered generators.  That would certainly mean less pollution, since it burns much more cleanly.

I have no idea what the fuel cost comparison would be.

Not too sure how high power a gas engine or gas turbine based genset can be made, I suspect a MW is not too foolish an idea. Certainly propane is a cheaper genset fuel than petrol - there is one that goes to the smaller scout camps that made the switch to calor gas a few years ago.

One of the reasons for using multiple gensets in a large field is the problem of voltage drop over distance, and the sudden step up in the complexity of the H and S environment that surrounds everything over 1kV line to line. 

If the regulations did not step change, then a field of a km or two across, it would be a lot more ‘green’ and more economic use a at low-ish HV in the 1- 3kV range to either bring mains to site or  to run out lines from central generation , and then use the Hiab to  drop transformers at the places where otherwise there would have to be gensets. (*)

Coming back to batteries and inverters, if you look at the batteries on the Rolls-Royce electric aircraft Spirit of Innovation,  that uses a half tonne 750V DC 6000 cell battery of ~ 70kWhr capacity capable of about 15 mins of flight, and giving up to half a megawatt steady state and short bursts of 150% of that  for take off. That sort of power with mains inversion  would do to give you time to start the genset if central power failed at your festival.

Mike.

(*)

There is no technical reason not to do this already - flexible cables and connectors for the low kV range are already common in South African mines, and they can be made very safe - the obstacle here is largely regulatory.