Solar at the dairy: how to crunch the numbers

SolarDairy

I’d love to install a solar system here on the farm but since we use most of our energy in the dark or at sunset, it’s a real challenge make it affordable. I’m really grateful to dairy energy expert Gabriel Hakim of AgVet Energy in Warragul for writing this guest post on how to crunch the numbers!

Energy Audit with Gab

Gabriel Hakim and Wayne check out the dairy during an energy audit back in 2012

With the backdrop of the recent closure of Hazelwood, and continued uncertainties over supply and prices more and more dairy farmers are asking “Can solar work for me?”.

The way electricity is consumed on most conventional dairies – early morning, late afternoon, and overnight – means it is a challenge to maximise the direct benefits of solar.  In southern Australia, most of the electricity generated by photovoltaic panels (PV) occurs between milkings, during the middle of the day.

How this electricity is used has huge implications for the economics of PV.  The three broad options are:

  1. sell all unused generated electricity into the grid;
  2. store unused generated electricity and use it later; and
  3. change the timing of electricity-using tasks so they make use of the electricity as it is generated.

The reality of course, is to deploy a combination of these options. This post explores option 1 for installing solar on an existing dairy with:

  • Twice-a-day milking. 6:00 – 9:30 am and 3:30 – 6:00 pm (includes milk cooling time)
  • 450 milkers calving all year round
  • 40-50 units
  • Conventional cooling (glycol chiller, with final direct expansion cooling in vat)
  • Conventional cleaning (warm pre-rinse, hot wash, hot final rinse) – ~1,600 l hot water/day
  • Average daily electricity consumption 450 kWh (large user)
  • Electricity charges are 22.6cents/kWh and 10.1 cents/kWh (ex GST and after discounts have been applied) for peak and off-peak respectively. Annual spend on electricity is $22,206.71 (ex GST).

How big should the PV system be? 

The optimum size depends on several things such as; the load profile, how much of your consumption you aim to off-set, the available roof space (or ground space), and how much you’re willing to invest.

For this case, let’s choose a 50 kW quality brand PV system. The going price for this roof-mounted system on a tilt frame is $59,545 (ex. GST) net of RECs.  And, from July 1, 2017 the feed-in tariff rate increased to 11.3 cents/kWh.

Whilst the calculations for the economic analysis might be straightforward, the real challenge is making realistic assumptions about power usage.

Unfortunately, many solar systems salespeople don’t have a good appreciation of dairying and I have seen too many instances where the intended outcomes are never realised because of poor or incorrect assumptions.

For the example dairy, the maximum proportion of PV generated electricity that can be consumed directly is 48% because the bulk of the electricity generated is typically between 11:00 am and 3:00 pm, when very little or no equipment is operating.  To increase the proportion of direct consumption would require shifting tasks to this timeslot – option 3, to be discussed in another post.

The PV system

PV system Size 50 kW PV capital cost $59,545
Average annual electricity generation  72,560 kWh Simple payback period 5.8 years

GabrielSolar1Table

Even with 48% of the generated electricity being directly consumed – and 52% being exported – the annual savings are substantial, $10,613 in year 1. The simple payback period for this investment is 5.8 years. Higher tariffs or future price increases would make the payback shorter.

The “take-home” lesson here is that the more you can consume directly the better the financials stack up.

If the PV system was bigger, say 80 kW, you might be able to capture a little more for direct use during the winter months but you will be simply exporting more to the grid. It is still financially attractive but requires more investment (~$95,300) and payback time is extended by about six months.

Financing solar
The financial indicators above assume farmers have the money to fund this investment stashed under the pillow (we all wish it was).

Fortunately, over the last three years or so the financing market has become far more amenable to funding energy related equipment. The number of institutions that offer products targeting this space seems to grow every month.

The Sustainable Melbourne Fund (http://sustainablemelbournefund.com.au/), for example, has broadened its focus to regional areas and is very interested in getting involved in the agricultural sector. They were really impressed by the environmental credentials of the Green Cleaning System I designed a few years back.

A cashflow-neutral investment
Financing an investment such as this can be very attractive as the savings in the electricity bills can be used to service the repayments. By negotiating a low (interest) rate and reasonable term length (5-7 years), these types of projects can become cashflow positive from the very first bill.

If we were to finance the above 45 kW PV system over a 7-year term, the fixed monthly repayments would be $846 equating to $10,152 per year. If we manage to achieve 40% or more direct consumption of the PV generated electricity, then this project would be “cashflow neutral” or even slightly positive from the outset. After seven years, the saving can be banked.

So, “Should I go solar?” is worth thoughtful consideration. The option presented here is the least financially attractive of the three options but still has merit. Ensure that any assumptions made are directly relevant to your situation. Do your homework and don’t hesitate to seek advice.

Thank you, Gabriel, and Milk Maid Marian looks forward to the next installment of solar smarts.

Slugterra brings the dairy to a halt

slugterra-games Pic courtesy of watchonlinecartoons

It’s stinking hot, we’ve finally got the cows over to the dairy after an “exceptional” road crossing (“exceptional” is when you have two cars forcing their way through the herd at once in different directions, while a flashing fire truck appears over the crest). Then, with just 16 of the 255 cows heading out into the paddock, the machines fall off.

Wayne – who started life as a fitter, turner and boilermaker – is uncontactable at the little man’s swimming lesson an hour up the road. It’s down to Clarkie and me. Running out of ideas, Clarkie is changing the belts that power the vacuum pump. I am looking for vacuum leaks. There’s one at the milk receival can but not enough to cause a total failure.

Standing under the sprinklers in 33 degree heat and udders bulging with milk, the cows wait.

We start the pump again and realise that no water is coming out of the water exhaust. The pump is hot. Too hot. Have we cooked it? Pumps like these cost thousands and, without it, there will be no milking tonight or in the morning. Sweat trickles down my neck.

dsc_6228

Brushing cobwebs aside, I look for the water inlet. There’s a rubber hose leading from a water-filled drum. It comes off easily and the elbow connecting it to the pump is full of goo. My spirits lift as I pick the slime out with my little finger. Clarkie digs into the port of the pump. A massive slug comes out. Could this be the answer?

We put it all back together again and press the start button. Only a few pitiful drips of water come out. Still no vacuum. The cows wait. I brush the sweat out of my eyes with a now filthy T-shirt.

The people we bought it from have folded so I reach for Dr Google. The pump is a “Flomax” water ring and, to my massive relief, the vacuum pump expert at Dynapump answers the phone! It turns out Dynapump does not make our pump but I have found not only an expert but a gentleman in Andrew, who offers to help with advice if I can text him a photo.

At the same time, Wayne finally answers his phone and tells us to prime the pump with water but not to put it down the exhaust.

“There must be a tap or a plug on it. You could damage it if you put it down the exhaust.”

We can’t see any way to add water, so Wayne gets a contact of his own, John, to call. But John is an hour away, at least. He suggests having another go at the pump with a long piece of wire. I do. Still nothing and this time, the pump begins to growl.

It’s 5.30pm. The cows have been waiting in the yard for an hour and a half. I make another call to Wayne and talk to him about sending the cows back to the paddock and letting Clarkie go home. My heart is in my boots.

Andrew of Dynapump rings back. Our water tank is too low to flood the pump. It has to have a water level at the same height as the shaft to make the pump seal so it can generate vacuum, otherwise it needs vacuum to draw in the water. We have a Catch 22.

There is only one way to get water into this pump and it involves a hacksaw. Clarkie and I nod and compare our weapons. His is sharper and in no time, we are pouring water into the exhaust. Yeah, there is a risk we could damage the shaft if we put too much water in but the belts should slip enough to protect it.

A roll of duct tape later and we’re ready to press start one last time. With an almighty cough, the pump springs into action. Just the hint of a grin spreads across Clarkie’s tanned face and he says: “We’re a bit clever, aren’t we?”.

Wayne and Clarkie are down there now milking together. I stink of sweat, cow and grime but I am one very grateful farmer. A breakdown like this is tough on the farmer and worse for our ladies. A huge thank you to Andrew of Dynapump for answering a milk maid’s desperate call that would have been much easier to dismiss as someone else’s problem.

The sun is up and so is the sparky (or, the day began pear-shaped)

Dairy cows are rounded up before dawn but, today, they slept in. We had a bit of a disaster in the dairy last night that would have meant the girls missed breakfast. That certainly would not do, so while they waited for the sparky to weave his magic in the grain auger control box, this is how the cows enjoyed watching the sunrise.

Sleeping in

Sleeping in

Two hours later than normal, with steaming breath and swaddled in layers of clothes to ward off the still chilly air, the kids and I had the rare treat of a family morning round up.

Rounding up was noisier than usual, too!

Rounding up was noisier than usual, too!

The cows seemed to take it all in their stride but we are lucky this has happened late in the season when milk production is falling away. Farmers are so fastidious about rising early because a late morning milking means painfully-full udders and the risk of mastitis. Wayne took the opportunity to do a heap of other farm chores while the feed system was repaired and will milk the cows late tonight to help even things out for the cows again.

A big thank you to Dutchy the sparky for getting out of bed so early on a frosty Sunday morning. It turns out that, in dairy country, the cows rule the lives of farmers, their families and even the local electricians.

Cows having a sleep in

GPS on the farm

A GPS comes in handy on the farm. We use it to plot farm infrastructure and maps, while contractors use them to fertilise and sow our pastures. Today, it did another very important job: science teacher for Zoe.

"We've got four, no, FIVE satellites!"

“We’ve got four, no FIVE satellites!”

With 250 cows drinking up to 200 litres of water each on a hot day, we need a pump we can rely on, so when the pressure began to fall, we were quick to investigate. Bugger. Faithful old Davey is getting pretty tired. An inch has been worn off his venturi and the jets need replacing. It’s a major overhaul, so we’ve decided to buy a second pump to keep Davey Senior company in semi-retirement.

To make sure Davey Junior is right for the job, it’s important to check how high he needs to suck water out of the river and then how high he needs to push it around the farm, which is where the GPS and its six-year-old pilot came in.

The GPS is magical to my little girl, and why not? It’s covered in buttons and talks to satellites whizzing through space at thousands of kilometres an hour. She was practically an astronaut today!

The tractor, the toddler and the ejector seat

The neighbours will think I have gone mad or won Tattslotto. The Macdonald farm is not known for gleaming machinery but, in the last few days, an updated tractor has arrived, followed by a new feedout cart.

The reality is that our ancient tractor was getting so tired I just had to trade it for a 6-year-old replacement. Then, in spectacular fashion, the geriatric feedout cart snapped a structural member and twisted itself into an irredeemable mangle. We’re currently feeding the cows 4 tonnes of hay and silage per day and, without it, the feeding regime would take at least an extra two hours that Wayne just doesn’t have.

The tractor may not be brand new but it’s seen barely any work in its former life as a parks and gardens curator and has gleaming paintwork teamed with dark tinted windows that instantly captures a milkmaid’s heart. Fortunately, there was urgent and important work to be done, so with toddler strapped to chest and dog in hot pursuit, I set off to christen the Green Machine and its pristine bucket.

And, oh, the experience was indeed rapturous! The new tractor was clearly designed by another child-wearing tractor driver. Alex cannot reach the forward-neutral-reverse lever on this model and a single, aptly-named joystick controls the front end loader’s up-down and tilt all at once, eliminating even more hazardous handholds!

Christening the Green Machine

Christening the Green Machine

The only thing that got me out of the tractor seat was the little man’s demands for food.

The next day, Wayne got his turn. Had to do some customisation. There was a cumbersome box to remove, the little spray tank that obscured the view, the radio key to re-enter, the steering wheel positioning and the ejector seat to adjust.

Me: (Distracted by toddler attempting to wear potty as a hat) “Hang on – what did you say?”

Him: “It was nearly impossible to squeeze in behind the steering wheel, so I had to get it up out of the way. You can see where the council blokes have been wearing the upholstery away trying to push their big…”

Me: (Hastily) “No swearing in front of Alex! What was that about the seat?”

Him: “Oh that…Yeah, well, I’d put the steering wheel up nice and high but that meant the seat was too low so I had to get it up too.”

“There’s a button between your legs to push and – can you believe it? – a little compressor starts up ‘brrrrrr’ and I’m being lifted up towards the roof! Problem is, the seat carries you away from the button and, pretty soon, you’ve got your head between your knees trying to keep your finger on the thing.”

“As you’ll no doubt remind me, my perfectly proportioned arms don’t reach all that far, so once I couldn’t touch the button any more, I let go and sat up to have a look. All I could see – right before my eyes – were the air-conditioning controls.”

Me: (Laughing) “Those ceiling-mounted knobs? Did you hit your head?”

Him: “Yep, it’s the world’s slowest ejector seat. Put that in your OHS manual.”

Because diesel is the new asbestos

Diesel Bobcat without windscreen

Breezy is beautiful

Diesel fumes have always left me feeling sick and it turns out my queasiness is justified. A report in the West Australian explains:

“Researchers from the WA Institute for Medical Research and the Telethon Institute for Child Health Research found that children with fathers who were exposed to diesel exhaust fumes at work about the time of conception were 62 per cent more likely to have brain tumours.”

“The results, published in the International Journal of Cancer, also showed that children of women exposed to diesel fumes at work before the birth had twice the risk of brain tumours.”

Scary stuff? Yes. According to the WHO, diesel is the new asbestos.

“Experts at the World Health Organisation (WHO) say diesel engine exhaust fumes can cause cancer in humans. They say they belong in the same potentially deadly category as asbestos, arsenic and mustard gas.”

We are lucky to live far from city pollution but we do have a diesel car, diesel tractor and diesel UTV that gets me and the kids around the farm. That new UTV came with a roof and windscreen – a combination that, ironically, may have threatened our children’s health. Unfortunately, it seems the windscreen created negative pressure and built up a vacuum that sucks air from behind and around the UTV back over the cabin. With it came a lot of dust and a strong smell of diesel fumes.

The windscreen is now stacked neatly against a garage wall and we are breathing easy once more.

The dairy farmer’s calendar

Summer is the laziest time of year for a dairy farmer but when Wayne and I started writing a “to do” list yesterday, my head began to spin a little. Not satisfied with a mild head rush, I went on to draft a rough calendar:

The Annual Milk Maid’s To-Do List

Lazy Summer Days

  • Milk cows
  • Pay bills
  • Deal with crises (pump breakdowns are popular this season)
  • Begin drying cows off for their annual holiday
  • Make hay
  • Have we conserved enough fodder? Consider buying more
  • Begin feeding silage, crops and hay
  • Return cow effluent back to pastures
  • Spend a day changing rubberware in the dairy
  • Control blackberries
  • Vaccinations, drenching, branding, preg testing
  • Big maintenance projects (the stuff you put off the rest of the year)
  • Dream of the next Great Leap Forward

Autumn Anxieties

  • Milk cows
  • Pay bills
  • Deal with crises (milk quality issues popular this season)
  • Continue drying cows off for their annual holiday
  • Special feeding regime for expectant cows
  • Welcome and nurture new calves
  • Test soils for nutrient levels
  • Repair cow tracks
  • Sow new pastures
  • Fertilise pastures
  • Return cow effluent back to pastures
  • Chase revegetation grants and order trees
  • Maintenance
  • Still feeding silage and hay
  • Nude rain dancing in full swing

Winter Woes

  • Milk cows
  • Pay bills
  • Deal with crises (calving emergencies popular this season)
  • Welcome and nurture new calves
  • Fence and spray areas for revegetation
  • Spend a day changing rubberware in the dairy
  • Feed three groups of cows different rations
  • Mating program in full swing
  • Consider another drenching
  • Buy new gumboots and practise rain dancing in reverse
  • Redo budgets after milk factory announces opening price
  • Keep chin up

Supercharged Spring

  • Milk cows
  • Pay bills
  • Deal with crises (unpredictable weather popular this season)
  • Train the new members of the herd
  • Visit the accountant (and maybe the banker)
  • Fertilise, fertilise, fertilise
  • Vaccinate and wean calves
  • Thoroughly clean and disinfect the calf shed
  • Plant trees
  • Control thistles
  • Make silage
  • Sow summer crops
  • Make grass angels

I know I’ve missed stuff – lots of it – but it should give you an idea of what happens day-to-day and season-to-season on our very average Australian dairy farm. So, dear Reader, as we head into 2013, what do you want to know more about?