Jump to content
Sign in to follow this  
twisty

Cheap Electricity!

Recommended Posts

Sort of ...

Glort mentioned an interest in power (electricity) generation and storage (excerts below with comments and questions). I share his interest but I'm an ex-(aircraft) electrician and I've forgotten more than I remember .... although I can still explain helicopter advancing blade theory. The shit you remember!

I've got some 250 acres with cows, dams and no running water. The sheds roof areas are north facing and about 1200m2 with 100k litres storage in 5 plastic tanks. We are mains connected with the ability to connect a generator (petrol) if the power goes out. Fitting a grid feed in system would be part of the mix. And ... being a greedy farmer, if I could make a quid, okay!

So, my idea ...

I get two more tanks (40kl) and sit them on the top of the two shipping containers I have sitting next to the tractor shed. Two other tanks already sit on the opposite side of the shed at ground level. Now all I have to do is figure out if I can cycle the water using micro hydro generation with wind and/or solar pumping back to high storage. Another thought is to use a smaller (500l) "header" tank at 10 metres agl. I also have a solar hotwater system not being used and wonder how I might integrate it into a system.

or/and a poly hybrid system ... back to Glort.

I have " Heard" of someone that runs a veg fired generator that backfeeds in to the mains. Using an induction motor as a generator the thing Phase locks to the frequency and having the field energised by the grid, the thing can't Island and be a danger either. By switching over to a C2C setup, the system can be self sufficient if the main power is isolated.

I don't understand. Was the veg genny driving the induction motor?? That doesn't seem right. Or are you describing two different systems? What is C2C?

By backfeeding directly into the household supply, the power runs everything in the home to it's max capacity and any shortfall is made up from the grid. When the power generated is excess to requirements, the meter spins backwards. In this way you get the same rate for the power you make as the power you use which is only fair.

Simple, but, how many amps are you thinking? Just putting some rough numbers to the problem. A 10 amp (240v/50hz) current generates 2.4Kw. At about 20c a Kw thats $0.50/hr ($12/day). That might be close to a winter electricity bill. Generating 240AC and backfeeding must be simpler than rectifying generated DC.

I wonder what the hoops would be to setting up things on an approved basis and if something like a micro Hydro would qualify for renewable energy grants/ bonuses/ tariffs?

The Rainbow Power Company has some good info and it seems Queenslanders are the only ones getting a feed in tarrif of any worth. They've been around for a while and also have hydro stuff here. Build it Solar has a lot of diy stuff.

I've also got an old holden jackaroo with a small diesel engine. I wonder how much power I could generate running on vegie oil .... I've got 1000l food grade tanks and often stop for take away.

Cheap power with a bit of ingenuity. What do you think?

Share this post


Link to post
Share on other sites

I get two more tanks (40kl) and sit them on the top of the two shipping containers I have sitting next to the tractor shed. Two other tanks already sit on the opposite side of the shed at ground level. Now all I have to do is figure out if I can cycle the water using micro hydro generation with wind and/or solar pumping back to high storage. Another thought is to use a smaller (500l) "header" tank at 10 metres agl. I also have a solar hotwater system not being used and wonder how I might integrate it into a system.

This idea has some merit.

There are companies/ businesses set up here and in the states that just pump water up hill and let it run down again.

They pump the water up to a dam or lake at night when they buy the power from the electricity co at a lower off peak rate. During the day they let the water run back down again using the pump motors as generators and sell the power back at a higher rate.

Surprisingly the power companies are OK with this. Id gives them the ability to have a buffer in times of high load to supply local areas and this has other benefits for them so they are happy for these systems. I looked it up a while back and there were 5 or 7 such systems running in NSW.

Can't remember what site I found the info on, may have been water board or electricity co.

You would have to work out the amount of power you could pull from the 10K L you have and the pump back time. Being on a farm you may also be able to do a deal on the power you buy and sell.

I had a look today at setting up these systems properly and they are classed the same as solar. You need an inverter which would run about $4k for a 5000W system and it has to be installed by a certified person. The tarrif that admin quoted in the other thread seems right much to my surprise. The general buy back is said to be 6-8C a KWH.

It seems the inverters work by supplying the household first and then the grid in the case of over supply. To me you would be better off just offsetting your own consumption on a 1:1 basis and reducing your Bill to 0 as if you go into credit and you are doing it on the sly you are sure to get an inspection.

I don't understand. Was the veg genny driving the induction motor?? That doesn't seem right. Or are you describing two different systems? What is C2C?

The Veg motor drives and induction motor.

Briefly, you start the engine and run it under the rated speed of the electrc motor. You then switch on the electric motor and bring the engine up to a speed where it overdrives the motor by about 10%. This turns the motor into generator and it's energised and phase locked to the grid. You can do this on a single or 3 phase motor but 3 phase is best as it's more efficent and you don't have to worry about capacitors in the system.

If when the motor is generating, the mains power crashes, the fiels will collapse in the motor windings and the thing will stop generating. this is a very hand saftey feature so anyone working on the power lines won't get BBQed nor will your motor try to supply the entire neighbourhood.

In the case of overload, the flux field in the windings will also drop and the motor will again stop generating which is like a built in overload protection. Very handy.

C2C is used on 3 phase motors to effectively gain a single phase output of the combined output of all 3 motor windings.

Say you have a 15Kw motor as a genny. On any 2 poles, you could get a ( theoretical) 5Kw output of any leg. You couldn't run a 6 KW load though as this would be more than that leg could supply. the way to get a single 15KW supply would be to add a capacitor of the right value ( you can work it out for each motor) across 2 legs and then 2 capacitors or a single one of double the value across another 2 legs.

What this does is bring the 3 120o offset " Pulses" together. the Caps act like an electronic delay between the phases so they all act like one. Now you can run that 6KW load no worries and another if you wish as well.

C2C is for when you want to run the motor as a stand alone genny, not as a grid tied one.

The caps also control certain other aspects of the motor like the field winding energising and the resultant output voltage. If the motor is overloaded, the field in the winding colapses and the motor stops generating.

When this happens as is often the case when trying to start the motor generating in a c2c config, the windings need to be " Flashed" to restore the small magnetic flux field to establish the magnetism needed. This is easy just by shorting a 12V battery across 2 poles like flicking the wire to make a spark. You can watch on a volt meter as the thing starts generating and come up to power again at which point you can reconnect the appropriate loading.

You can also adjust the output of the motor to the speed. For instance you could over drive the motor to a higher revs to get you IC engine on it's power curve but then lower the cap values to compensate and give you he right voltage albeit at the expense of frequency.

Simple, but, how many amps are you thinking? Just putting some rough numbers to the problem. A 10 amp (240v/50hz) current generates 2.4Kw. At about 20c a Kw thats $0.50/hr ($12/day). That might be close to a winter electricity bill. Generating 240AC and backfeeding must be simpler than rectifying generated DC.

A high current circuit is typically 20, 30 and 40A in 240V and that would be about the most I'd expect a normal circuit board to handle tops.

If I get my old Merc motor and a bigger 3 phase motor than the 7.5 Kw I have now, then I could easily sink 20 or 30 A into the circuit or have a couple of circuits and wire 2 legs of the motor across each. ( yes, one leg is shared.) AS a rough guess and it depends on motor to motor as there are some losses as one would expect, a 7.5 Kw motor should be good for around 5Kw output.

As a rule of thumb, you want a motor of double the HORSEPOWER ( not KW) to drive it. Something around 15Kw would be nice for a " Household" system if one had the HD wiring back to the board to support it. for this you would want around 30 HP from the driving motor.

I'll bet your farm is already wired for high current to the sheds and High output 3 phase motors are not hard or expensive to come by. They are also the far better choice than a regular generator for grid feed as they will automaticly phase lock where with a normal genny you'd need an expensive inverter or interlock controller.

Everything that comes from an induction motor being used as a generator is already AC. The frequency is controlled by the grid in the case of a direct feedback and in the case of a self sufficient C2C setup, the value of the caps control the frequency. These are not stable however and the frequency and voltage will change with the load so a c2c setup is best for constant loads ( unless a dump controller is used) and things like lights etc which don't give a rats about frequency.

I've also got an old holden jackaroo with a small diesel engine. I wonder how much power I could generate running on vegie oil .... I've got 1000l food grade tanks and often stop for take away.

The power you could generate would be limited by the size of the motor you were turning and the amperage rating of the cable you were feeding into. With an engine like that, You'd probably be good for 20-30 kw effectively being sunk back into the grid. That's 125 Amp by my reckoning.

More than your meter would handle unless you have 3 phase and fed it back across the 3 legs or you were running some other load on your property to suck some of it off.

Share this post


Link to post
Share on other sites

Something else I thought of today that might suit your cheap power needs and could work well with the resources already on your farm.

The first one which would be great with the tanks you have is a methane Digester. Cow Dung is a fantastic raw material for these things and you could simply use the gas produced to fire a gas hot water heater or an engine.

Basically you put the dung and you can use vegetable ( and human if you are so inclined) waste onto a tank, let it ferment and the bacteria do their trick and you get methane gas. You could get enough easily to make running a generator viable and you could also set up a co-gen system for keeping the tanks warm to increase production or to have warm or hot water for washing your dairy facilities etc.

If you milk the cows you would probably get enough slurry from washing down the milking shed when you were done to feed straight into a digester without having to go pick up cow pats around the place.

Once you have the gas, you can supplement a diesel engine with it or get any old petrol engine and do an easy gas conversion. Be great with car engines because you could get them cheap from wreckers and just replace them with another used one when they did wear out.

The other thing you could look at which is not as simple IMHO is to buy or build a wood gasifier.

If you wave a decent amount of timber on your property, you could use that as the fuel to run a petrol engine to drive an induction motor or genny.

I believe commercial models are made although I don't know if they are available here. There is heaps of Vids on you tube and info on the net about building the things.

If you are in an area of decent wind, maybe a wind turbine could be of some help. You can Build your own alternator out of F&P washer motors or make a PMA out of a car alternator. You can also buy PMA's at a reasonable price on the net. From there you would have to build a tower and the blades or buy those as well.

Till recently the problem with wind on a diy scale was the need for a costly inverter if you wanted to grid feed. You can now buy on ebay small Plug in units that you feed from a battery or direct input and they plug into the powerpoint and push the power back into the mains.

You can get these from 300W up to 5000W. A 2500W unit is under $600.

With one of these units, you could use the windmill to charge batteries and then feed back into the mains or get an engine driving a couple or 3 ordinary 24V alternators into a couple of batteries. Connect the grid tie inverter and you are back feeding.

This would have to be about the simplest, easy to set up system you could have. Get your veg ( or methane) fueled engine, add the alternators and inverter and you are there.

If we assume using your engine on Veg and $1000 in setup costs for alternators and the inverter, you could easy produce the $12 a day of power in your original calculation. That would give you a payback time of under 3 months.

The beauty of using an inverter like this would be the whole thing would be plug and play on the high voltage side. All you would need to do would be wire up the alternators to a couple of batteries and connect the inverter to the batteries and a power point.

Easy and a lot cheaper and more powerful than a standard 1.5Kw solar system.

If you had a car engine and a High current Circuit or 2 regular circuits close by, you could add more alternators and another inverter and make even more power depending on how much you use and want to offset.

You could also run a single inverter system 24/7 if you wired in some shut-downs on the engine for low oil pressure or overheat. There are generator controller panels already available for this. I have one and it will even monitor battery voltages and start and shut-down the engine as the batteries need charging.

I intend to wire up a Lister with the appropriate sensors to this panel so I can run it standalone when I get organised.

Share this post


Link to post
Share on other sites

Thanks Glort. You're a treasure.

Yeah ... there's a gazillion ways of generating electricity. Storing it is the trick. Feedback is a form of storage but if the grid goes down, well. Batteries are okay but I'm wary after spending a long time in "battery rooms" servicing the bastards, so, not high on my wish list. I do have a small solar/battery setup for the hot house watering system and that works just fine with batteries that no longer start vehicles.

Methane is a good idea except, we're beef cattle farmers so collection is a pain in the bum. A wood gasifier sounds like a lot of hard work. I think, for my situation, I still prefer the micro hydro using water, at height, to store energy. The thought is to run it 24/7 and using the $12/day that's ... uummm ... $4380 a year. two more tanks ($5k) and $5k for microhydro/solar/wind/ pump/generate system, and other stuff. Two years is pretty good.

A plug-in inverter? Do you mean like this? hhmmm ... I like the idea, very simple.

Pic of the shed and tanks. The two containers are on the other side of the shed.

post-21-0-33757200-1341488080_thumb.jpg

Edited by twisty

Share this post


Link to post
Share on other sites

I guess the first question I'd ask is do you have a problem with power outages?

IF you do, then I'd say either a battery system or a generator are you most reliable options.

The hydro idea the way you want to do it with tanks and pumping with a windmill would be better as a cost reduction system IMHO. If you had a nice flowing creek, Different story.

The other thing that occours is if you are going to use a windmill as your energy source, You'd be better off either hooking up an alternator to it and generating the power direct or using an electric water pump running backwards off the windmills output as an induction generator.

This would seem to me to have better potential efficencys than pumping water around the tanks.

If a windmill water system is what you are thinking, I don't think you are going to get a lot out of it.

A 4" pump on a windmill with say 12Ft blades is going to pump around 3Kl an hour. That means it's going to take under ideal conditions around 12 hrs to recharge you 40Kl Tanks so you will only get to operate them twice a day. Sitting the tanks on containers is only going to give a max of 12 Ft head if that which isn't a lot. With that a pelton wheel type arrangement on the alternator may be best. I still see the output as being pretty low however.

If you are going to "reuse" the water in the tanks, you are going to have to have tanks at the bottom for the water to be held in till it's pumped back up and those tanks would have to be lower than the generator height which would logically be at ground level. You'd either want to sink them in the ground or pipe the water from the generator to lower ground. Of course then you have a reduction in your pumping capacity from your mill.

I'd be interested to get more input on your situation and prefrances but I can't at this stage see the tank arrangement being able to produce or store much power at all.

I really think your best bet would be to go into town and see how much veg oil you could get hold of and look at setting up your rodeo motor on an induction motor.

Do you have any idea of what your present consumption is or a figure you want to aim for in your generation setup?

Share this post


Link to post
Share on other sites

The hydro system is dead in the water! After a bit of research I've discovered that achieving even 100watts from a micro/nano hydro system with my configuration is almost impossible. The problems are, not enough water and not enough head. A 7 metre head gives 10psi and is the maximum I could achieve. The chart below for a nano hydro system tells the story ...

post-21-0-46511300-1341703126_thumb.jpg

Our power supply is very reliable. I've been interested in power generation and storage since I was a little bugga. Problem is I'm also easily distracted and projects get put aside. I'm just playing with ideas and, perhaps one day, I'll dig the solar hws out and hook it up as well.

Glort, I like the veg oil engine and will do a bit more research. I could run the tractor on it as well (save a grand or two a year). Thanks for the input.

Edited by twisty

Share this post


Link to post
Share on other sites

If your power is reliable and you just want to cut costs, The veg driven induction motor would work well and be able to give good savings.

That said, the first thing you need to do is source your fuel Oil. If you are in a bit of an out the way town you won't have any problem. If you are in a major it may be a little more difficult but shouldn't be any great problem. Get the oil ( and I do mean get it NOW) before you even start setting up the genny.

Having a reserve of oil that has had some time to settle before you start using it gives you a big advantage from the start and ever more.

I'd strongly Suggest a basic water injection system for the gen setup because no engine likes being run at the same RPM for hours at a time especially on veg. The WI will stop it claging up and keep the internals clean... maybe cleaner than they are to start with!

Using an engine like this you can easily make it a co-gen system and extract heat from the coolant and exhaust. You can easily back feed or set it up with some transfer switches to be a stand alone system.

What sort of powerbills do you have now and what is your main power use on the farm?

Share this post


Link to post
Share on other sites

I used to maintain a dial up control system for an old man back in the mid 90s. The system used a pump and mini hydro setup down around the snowys. Pump the water up hill at night, generate during the day.

Share this post


Link to post
Share on other sites

I'd be very interested to hear a LOT more details about the system.

How much water, what height, size power of pumps and especially differential between the price you bought the power for and the price you sold it.

Share this post


Link to post
Share on other sites

Just came across this thread again while looking for some info on Google. 

Did you ever get round to doing anything with your own generating set up Twisty?

I did get myself a Lister CS 6 Diesel engine and have been playing with that a bit and my little horizontal China Diesel. I have also been doing a bit of testing with a Fisher & Paykel washing machine motor. These are permanent magnet motors and are the 1st choice for the wind and micro hydro crowd. 
I tore the old machine apart and without touching anything, spun the motor with my cordless drill and got 800 Volts out of it. Apparently with a more powerful drill you can get 1000V in their standard configuration. 

They can be easily re-wired to give 12, 24 or 48V but I haven't decided which way I'm going to go yet. 

There is a 30Kw Generator I'm talking to someone about that I could drive off my Merc motor. All I'd need is an add on governor which would run about $300-350.  A normal house is wired for about 20 KW so a 30 KW genny would be enough to run everything in the place.
Simultaneously.  :0)

Share this post


Link to post
Share on other sites

G'day Glort,

 

I've done nothing about electrical generation.  I've been busy fencing and cursing the weather.  I'm just doing a steel cleanup and have a few old washing machines to get rid of.  Time to get the motors out.  Thanks for the reminder.

Share this post


Link to post
Share on other sites

The only motors I am aware of in washing machines that are any good as generators are the Fisher & Paykel one because they are permanent magnet types. 
I haven't done a lot with those yet other than basic testing.  They would be best suited to re-wiring to make an efficent alternator for battery charging or grid back feed. 
I came across a bunch of 2Kw solar inverters last year and these would be perfect for use with these motors. I would just need to rectify the three phase output to DC which is cheap and easy and then feed it into the solar inverters which will condition the power and feed it back to the gris spinning my meter backward for anything above the power I am using at the time. 

These things are real popular to convert to wind generators so if you get good breezes, some wind turbines may be a great solution for you.  The benefit I would see is the things can work 24/7 in the right areas and are virtually maintenance free. Unlike an engine which would require you to supply fuel which in the case of veg you would have to collect and filter, once you built the wind Gennys they would require pretty much non of your time. 

You could possibly mount them on a shed roof making the hardest part, the tower, a lot easier. While the power output is lower than a generator setup, the cost is dramatically less as well and if you set up several of them, the output would be multiplied and coupled with the potential for constant operation, the KWh generated could be very significant. 
It' really does depend on your location though. 

I'm in suburbia so wind is totally impractical but I'm still inclined to build a wind turbine and stick it up on the shed roof for  chits and giggles. With the efficiency of LED lighting, I could still probably get enough power to fill the lighting power needs in the garages and learn a lot in the process. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...