electricity Power on Demand: The New Watt Meter

[KittenIsAGeek]

With Banhi's Automation Innovation Pack we gained the use of the Watt Meter.

This useful sensor sends a green signal based its configuration based on the current consumption of power on a given wire.

 

In this guide, I will design and build an on-demand power plant.  I will use the watt meter to enable or disable generators only when their power is required to meet the demands of my base.   By enabling generators only when power is needed, we can reduce wasted power.  We can also eliminate most of the batteries from our electric grid.  Eliminating the batteries can eliminate the power lost due to leakage.  Here you can see a stretch of about 100 cycles where there was almost no power lost in my base. 

The large spikes (up to 40 KJ) at the end are due to restructuring my power grid to accommodate renewable sources such as steam.  By the end of this guide, wasted power should once again be minimal.

 

So, on with my design process...

 

Step 1: Analysis of Power Sources and Fuel Deposits

So far, my duplicants have discovered four volcanoes, two oil wells, a natural gas geyser, and a hydrogen vent.  They are also producing most of their oxygen by electrolysis, generating some 'waste' hydrogen in the process.  There are also many large coal deposits, with a large number of hatches adding to the reserves.  So power is not going to be a problem, but managing my various energy sources will be.

I want to utilize my volcanoes to produce power with steam turbines.  In fact, I want them running as often as possible.  They are going to be my primary power source, and all other sources of power will only be used if demand rises above that generated by steam.  Right now I have them set up to run as heat allows, so there is occasionally power lost if they're running while demand is low.  This will be handled at a later time and isn't the focus of this guide.

Basically, after analyzing my power sources and fuels, I have decided that fossil fuels will only be used if renewable sources aren't providing enough.

 

Step 2: Design and Build the Power Plant

Bubbles, Camille, and Nails have found a suitable room to build their backup power plant and have started to clear out the room.

Spoiler

A critical part of the process is design.  Think about what you need to accomplish and what your inputs will be.  You should also think about what your outputs are, including waste products.  In this case, the backup supply will be petroleum generators.   The input, then, will be petroleum and the desired output will be electricity.  Our waste includes CO2, Polluted water, and heat.

Each generator will produce 2kw of power when operating, using 2kg/s of petroleum.  This means that one pipe can supply fuel to 5 generators which can produce a total of 10kw of power when they're all operational.  Two oil wells can produce at most 6.7kg/s of oil, which is then refined into 3.3kg/s of petroleum.  Thus I can't run these continually, but they're perfect for short-term backup power. (Side note: The efficiency improves dramatically if I boil the oil into petroleum, but that's a different project).  So my design will include some fuel storage, the generators, and the controls necessary to operate them when power demands.  I also want to be able to reclaim the waste polluted water and CO2, and I want the facility to be closed, so that there's no need for dupes to visit -- unless there's a problem.  Since this place is used only occasionally, I won't be bothering with tuning up the generators.  I also want to make sure that my generators don't overheat.  I'm going to achieve this by making sure that I can enable a cooling loop. 

Another consideration we should think about is how long we want the generators to run before there's a fuel shortage.  One liquid reservoir can hold 5 tons of fuel, so two liquid reservoirs will allow all five generators to operate for about 1000 seconds (16.67 minutes) or about one and a half cycles.  Since this is meant to be a high-demand backup facility, I believe that should be quite adequate. 

OK, nearly done...

Spoiler

OK, so we've got a self-contained unit that dupes can venture into if necessary, but shouldn't need to.  I've also designed it so that it shouldn't be too difficult to dig out the bottom and add more generators at a later date.

 

Step 3: Analyze your Design

Before we get into handling the electric output, lets look at the design of the power plant.  In the spoiler above you can clearly see five generators, a gas pump, a liquid pump, some liquid reservoirs, a couple gas valves, some wattage sensors..  Looks a bit confusing!  So lets see what we've got and if it will accomplish our needs.  I'm going to leave our primary design requirement (electric output) until last, since five petrol generators can clearly produce 10kw of power. So, lets start by looking at waste removal.

Spoiler

In the first screenshot, we see the piping overlay that shows the input petroleum and the output for the waste polluted water.  Its pretty straight forward.  There's a liquid sensor to turn the liquid pump on if there's more than 100kg pooled at the bottom.  This will keep it from trying to pump every time a drop falls to the bottom.

There's also a pipe segment that isn't connected to anything.  That will be my coolant loop which will be implemented later.  Anyway, in order to help manage the heat, I want to maintain a bit of air pressure.  Oxygen does better than CO2, and besides, I want to use my CO2 elsewhere.  So I have an atmo-sensor that is connected to a valve to set the initial gas pressure.  Down at the bottom I have a gas pump connected to element sensor.  The sensor will turn on the pump when it detects CO2.  The first valve limits the total flow rate to 990g/s, and the second valve is an oxygen-pass passive filter.  Oxygen will return to the top, and any other gas (CO2) will travel out the side.  Since the polluted water will occasionally off-gas into polluted oxygen, there's another passive filter that will separate it from the CO2 further down the line.  This means my power plant room should remain at about the same pressure as when I started, so that if I eventually do decide to re-design, I won't have to first deal with a lot of excess gas.

Both waste removal pumps are powered by a small transformer connected directly to the generators.  When the system is running, they'll have power.

Alright, fuel and waste are taken care of, lets look at the power:

Spoiler

All the generators are connected by heavi-watt wire.  This wire can handle a load of 20kw, so we should be good. The small transformer is supplying up to 1kw of power, so the two pumps have plenty of power.  While sealing up the room, I thought I might like to use a bit more of that power, so I ran an extra line out. Whatever.

The second screenshot shows the automation overlay.  While building my design, I decided to use an AND gate along with the watt sensor.  This will let me turn the entire thing off if I want, without having to fiddle later with the watt sensors.  Starting from the bottom and moving clockwise, I have set each watt sensor to turn on appropriately as power demands.  The first sensor is "Above 10 watts," the next is "above 2kw,' and on around to the last in the upper right which is set at "above 8kw."  And, actually, I messed up slightly in my design (details below).

Step 4: How the Watt Meter Works

OK, so we've designed the plant and we've set the watt meters.  However, there's a problem.  The watt meter senses the load on a line.  If you have 3280 watts of stuff running on your grid, then that's what your watt sensor detects.  It has no clue that you might have 1500 watts of renewable power feeding into the grid from two almost-at-temp steam turbines.  This leaves a difference of 1780 watts.  So how does the backup system know how much power it needs to provide?  Also, how do we handle fractions of power?  

First, we need to isolate the entire system from the main grid.  This can be done with transformers.  If your renewable generators are connected directly to the main grid, then transformers will only feed the "missing" power into the grid.  So, in the case above, my generator room watt sensors will see a load of 1780 watts.  However, one generator produces 2kw.  To prevent power from being wasted, one smart battery will be built along with the transformers.  This will act as a buffer handle the fractions of power.  This is where I messed up in my design. The first generator needs to be connected to the smart battery's automation, rather than to a watt meter.   Here's the corrected automation:

Spoiler

The top left is connected to a smart battery, set to 80/10.  This handles power needs below 2kw.  The generator directly under it has the watt meter set to "above 2kw."  The final three generators are set to above 4kw, above 6kw, and above 8kw.  The switch lets me enable or disable the entire thing easily.  The second image shows how the transformers are connected.

And here's a screenshot of it running.  

The heavi-watt wire shows the total load on the system of 1.86kw.  The watt sensor inside my backup supply shows 660.66 watts.  To make this screenshot, I had a tuned up hydrogen generator running on the main grid to simulate a renewable source.  

There you go.  5 generators, one smart battery, supplying power only as necessary to supplement randomly-running renewable sources.

[Gurgel]

Interesting idea. I usually use large battery-banks because I am going solar when I need real power, but this approach has its merits.

[BT_20]

Isn’t battery loss almost nothing? What’s the point of this?

[KittenIsAGeek]

I should add a little something.  When designing a system, check all your output numbers.  My liquid pump is definitely adequate for cleaning up polluted water, as it can handle 10kg/s and my generators can only produce 3.75kg/s.  Unfortunately, each of those generators releases 500g/s of CO2 vs the 22.5g/s of a NG generator.  Clearly one pump is insufficient. However, I have made an observation that my slickster farm uses an incredible amount of CO2.  I need to re-design to merge the two together.

 

1 minute ago, BT_20 said:

Isn’t battery loss almost nothing? What’s the point of this?

It depends on how you've built your electric system.  My last base, before the watt meter was introduced, had every generator (or pair, or so) on a smart battery.  The batteries had to be adjusted so that all the generators wouldn't kick on at once, especially if there was a fuel that I wanted to use sparingly.  I also wasted a lot of power from renewables, because of things like my generators kicking in during daylight hours.  

With this design, I can set up generator banks that pretty much regulate themselves.  If power is needed, they kick on.  If it isn't, they don't.  If I have one that runs out of fuel, another one will take up the slack.  I could, for example, build a 10kw block for NG, Hydrogen, and Coal.  Which ever one is first on the grid would get priority, but if I run out of fuel I don't have to adjust anything -- the next one kicks on automatically.  

[TheMule]

 

On 4/7/2020 at 2:49 AM, KittenIsAGeek said:

It depends on how you've built your electric system.  My last base, before the watt meter was introduced, had every generator (or pair, or so) on a smart battery.  The batteries had to be adjusted so that all the generators wouldn't kick on at once, especially if there was a fuel that I wanted to use sparingly.  I also wasted a lot of power from renewables, because of things like my generators kicking in during daylight hours

Sorry, I'm not sure I understand.

Wasted power happens only when demand is lower than production. If your renewable generators (turbines/panels) produce more than your demand, power is wasted, and nothing can prevent that unless you can control the generators themselfves but we're assuming we either can't (heat has to be deleted) or it doesn't make any sense (why turn solar panels off during daytime).

Battery banks are the only partial solution, they'll store the extra energy until they're full. But if overall power production in a cycle exceeds demand, you'll get wasted power sooner or later. Batteries only solve the problem of uneven power demand at various time during a cycle, if the overall demand is more than the renewable generators provide.

In a standard powergrid, if smart batteries are correctly configured, you should have zero wasted power if your demand exceeds renewable production. Petroleum, nat gas, coal generators turn on only to supplement the missing power.

Point is if you have wasted power with smart batteries, you have wasted power with wattage sensors, too.

I can't see any functional difference, other than generators are turned on in sequence other than all together. Yeah I guess if you have a very large power plant (like 20 petroleum generators), turning them on all at the same time with a single battery might be too much for smooth operation, but you can add a couple of batteries to even things out, or separate the gens in 4 groups each controlled by a battery with slightly different settings, so that they are not activated at exaclty the same time.

[KittenIsAGeek]

7 hours ago, TheMule said:

 

Sorry, I'm not sure I understand.

Wasted power happens only when demand is lower than production. If your renewable generators (turbines/panels) produce more than your demand, power is wasted, and nothing can prevent that unless you can control the generators themselfves but we're assuming we either can't (heat has to be deleted) or it doesn't make any sense (why turn solar panels off during daytime).

OK, so lets look at this a different way.  Your base has its power needs mostly met.  The average power produced is approximately equal to the power used.  However, occasionally you have some very high power demands.  This can create some difficult logistics, where you'll either end up with lots of batteries sitting around idling most of the time, OR you run them dry too quick during the period of high demand and get some brownouts.  

So, with the watt meter, you can connect a generator that only kicks on when the power load is above a certain point.  When there is no need for power, the generator just sits there.  It doesn't waste power with a battery that isn't being used.  

In my build above, I mentioned that I needed 1 smart battery to handle the fractional power, but I've since discovered this really isn't the case.  If you're using a transformer to isolate the load, then you can set the lowest watt meter to something small like 'above 100 watts' and the rest of your power network will handle the difference.

7 hours ago, TheMule said:

Point is if you have wasted power with smart batteries, you have wasted power with wattage sensors, too.

This isn't really true.  Batteries leak power.  I've had some very large battery networks and the net loss was noticeable.

7 hours ago, TheMule said:

I can't see any functional difference, other than generators are turned on in sequence other than all together.

The functional difference is that with the watt meter you can have a generator sitting there doing nothing for 10 cycles without needing it to kick on every so often to keep its battery charged.  Then when your demand for power unexpectedly rises above your power grid's capabilities, it kicks on to supply the difference.

 

[TheMule]

14 minutes ago, KittenIsAGeek said:

However, occasionally you have some very high power demands.  This can create some difficult logistics, where you'll either end up with lots of batteries sitting around idling most of the time, OR you run them dry too quick during the period of high demand and get some brownouts.  

It's not lots of batteries, it's one for each generator group. Typically 1 battery for 5 petroleum generators, maybe 1 for 5/10 nat gat generator, etc. It's not a large number of batteries at all. Of course it's different for very large grids (like with a big sour gas boiler and tens of generator) but in that case wasting power is hardly a problem.

Large arrays of batteries serve one purpose only, to store power that would be wasted anyway. Like from steam turbines (those you can't stop), solar panels. And that happens only if production significantly exceeds demand for most of the time, which is not your scenario. In your scenario, there's no large array of batteries because you don't need it.

 

20 minutes ago, KittenIsAGeek said:

This isn't really true.  Batteries leak power.

Yes, 5 smart batteries leak 2kJ/cycle. That's 3W. You hardly need more to control groups of generators. And again, say you have a very large grid with many groups of generators? Use 16 of them. Still 10W.

Each battery controls something between 2,000W and 10,000kW(or more) of power at a price of 0.6W.

One smart battery fully depletes in 50 cycles. 5 petroleum generators run for 2s to fully recharge it. 2s every 50 cycles. I don't call that a functional difference. Maybe you do, and we can only agree to disagree.

[Stoned]

I think the watt meter is not the optimal tool to control power supply generation. This is done so easily with smart batteries

Power demand is something different. You can use the watt meter to switch on certain transformers if you are below a power threshold, so that some equipment only runs when you have excess power. Can be done with batteries as well, but you might not want to have them where you would need them.

A very handy use is to avoid overload. When your main power line begins to hit the 20/50 kw mark occasionally, you can use it to switch off some generators or switch off parts of your base with a power shutoff, it works on heavy watt wires as well.

A battery bank that loads only when there is little demand and kicks in only when your batteries are depleted during spike power demand (I look at you bunker doors) is also possible with a power shutoff.

[storm6436]

  Not trying to put the idea down here, but the biggest change I made in terms of how I built out my power generation was to stop targeting a 90+% full rate on my smart batteries.  Swapping to a target of 50-60% virtually eliminated my overage waste.  Was I still losing some due to battery loss?  Eh, yeah?  But it was a trivial amount.  Might I be able to integrate this into my setup to lower said battery loss?  Possibly.  Unfortunately, there's an inverse relationship between total battery storage available and the volatility of charge in terms of that percentage... and the less you have stored, the less wiggle room you have overall if "something" happens.

[reccurentz]

I like it, use watt meter to control production and use smart batteries to control consumers. I already notice I have been putting my batteries closer to my consumers, since it allows me to put priorities on my consumer circuits. 

On 4/8/2020 at 4:00 PM, Stoned said:

I think the watt meter is not the optimal tool to control power supply generation. This is done so easily with smart batteries

Power demand is something different. You can use the watt meter to switch on certain transformers if you are below a power threshold, so that some equipment only runs when you have excess power. Can be done with batteries as well, but you might not want to have them where you would need them.

A very handy use is to avoid overload. When your main power line begins to hit the 20/50 kw mark occasionally, you can use it to switch off some generators or switch off parts of your base with a power shutoff, it works on heavy watt wires as well.

A battery bank that loads only when there is little demand and kicks in only when your batteries are depleted during spike power demand (I look at you bunker doors) is also possible with a power shutoff.

Watt meter can't control consumer, since watt on the line is calculated from consumer usage and not how much you are producing.  Controlling production is really the only use-case for the watt meter.

Lets say you try to turn off consumers when you hit a certain threshold, guess what happens? The watt goes down and now the watt meter turns the consumer back on, which triggers the threshold and ad infinitum.

A smart battery with a power shutoff in front of it does the job better. Example below:

Low Priority Consumers (turn off when smart battery is between 90-100) = Battery -> power shutoff -> consumers

High Priority Consumers (turn off when smart battery is between 80-90) = Battery -> power shutoff -> consumers

Add some small transforms in the mix and you can give 2k line a guarantee 1k of power, but the additional 1k at a lower priority.