Founder and director at DryMac, Adrian Padt spells out the impact of soaring energy costs on the macadamia sector while at the same time offers some practical solutions for farmers to cut down on their energy bills.
Following articles in previous editions of The Macadamia on the soaring energy costs and energy security being at an all-time low, we, at DryMac felt it was pertinent to re-address these issues, but to also showcase solutions to mitigate them.
“Macadamia farmers say the cost of fuel to run generators during Eskom’s rolling blackouts is crippling operations” The Macadamia Winter Edition 2023
To start, let’s analyse the figures:
Energy costs have increased by almost 300% since 2000. And Fuel prices have approximately doubled:
On the table below, we can see the Capital investment (CAPEX) and operational costs (OPEX) for Solar and Generators.
Now let’s look at the Eskom Transformer Line charges highlighting savings if one optimises the plant for a smaller transformer feed.
Further comparisons between Solar and Diesel (with Eskom line rentals as well as Heat Pump technology savings) are detailed on the following two tables
As one of the leading processing plant manufacturers I am often told by farmers and processors that if they had known about HEAT PUMP TECHNOLOGY and ENERGY EFFICIENT SYSTEMS, they would have gone with that from the start. The reality is, that even if you have invested in other systems, by changing over now, the savings that you generate from converting will give you a payback within 2-3 seasons and from then on the savings are compounded.
I also get asked whether to install SOLAR or a GENERATOR. The simple answer is that a generator operating cost (OPEX) as a power supply alternative can be used to cover a drop in power across an emergency or a short period, but at extended load shedding intervals it is unsustainable in the long term and subject to cost fluctuation and supply of diesel. Solar however can be a manageable solution as a power alternative as there are limited OPEX costs, little to no maintenance and investment can be typically amortised across ten to fifteen years. The resistance to solar has been from large CAPEX cost specified to cover a large solar system. And secondly that the sun only shines during the day meaning a similar large investment on batteries. The reality is that optimising the system and then choosing what runs at certain times instead of running everything simultaneously means that smaller solar systems will work adequately at a fraction of the capex cost. If we can reduce demand and identify the components of the system that are needed at certain times, we can reduce the CAPEX, OPEX and reduce electricity costs substantially.
Using an example of a typical 400 to 600Ton DNIS per season plant I suggest 6 immediate interventions that will start saving money straight away.
HOW TO SAVE MONEY TO MITIGATE THE ESKOM PRICE HIKES IN SIX STEPS
1 OPTIMISE sizes of your electrical and mechanical equipment
First and foremost, this has a direct impact on line charges. It is also of utmost importance that all electrical and mechanical machinery, as well as fans, need to be accurately specified. I often walk into a factory where they are using a 1.1kW fan where they might only need a 0.37kW, because most fans run 24/7 you’ll be tripling the operation electrical cost. Remove these fans immediately size the fans correctly and change them out. The recovery of the cost to pay for this fan change would be within one season.
2 AUTOMATE the electrical control for the plant
Control your energy by switching circuits on or off smartly with a PLC. What is key here is SMART PREFERENTIAL SWITCHING (SPS), this allows you to prioritise, share or isolate critical | non-critical functions choose exactly what turns on or off during load shedding. When dehusking one can automatically monitor and control supply for the drying units to either be switched off or down to (limp mode) low power consumption mode, IE it keeps one heat pump going with a recirculation fan, until dehusking is finished.
3 INVERTER TYPE TECHNOLOGY
Using inverters type heat pumps and electrical appliances saves up to 30%, they also regulate startup spikes due to their capacitive and variable frequency control. Using VFD (variable frequency drives) or VSD’s on electrical motors can also save power and limit power spikes.
4 HEAT PUMPS
Converting drying system from boilers to heat pump / dehumidifying technology can reduce energy usage by 30%, and converting drying system from elements to heat pump / dehumidifying technology can save the heating energy up to seven times more efficiently (700%!)
5 POWER FACTOR CORRECTION
Power Factor Correction (PFC) can provide several benefits for your electrical system, such as lowering electricity bills by reducing apparent power and demand charges, increasing available capacity and reducing overload risk of equipment, improving voltage stability and quality, it will also reduce demand in some instances with up to 40%! (Typically 5-10%)
6 SOLAR POWER
Of course this discussion would not be complete without talking about solar. Clients are often dissuaded from a Solar option when they see the massive amount of capex required to run their entire plant. However, systems should be sized to run what is required rather than be sized for everything running simultaneously. From our experience, we’ve established that a 3-phase 15kw system is adequate to run and manage a 400t-600t plant using a 30KVA lithium battery backup (provided you have spec’d and sized your plant correctly). The cost of a 15kva 3-phase system is R300/R400k as opposed to a 100kva 3phase system which would cost you in the region of R3/5 million. Also bear in mind that it is scalable, so you can always start off with a smaller system and increase this when budget and demand is required”.
David Davidson a macadamia farmer from Mtubatuba says in stage 6 he has 10-12 hours of power outage daily. “My 15kw of solar panels and 30kwhrs of batteries run dehusking and drying during the day, and drying only once the sun has gone. Alternatively, a generator would use in excess of 1500 litres of diesel for stage 6 load shedding monthly. in effect, my DryMac MacCurer curing system means minimal electrical usage so can run off a small solar system – no diesel generator at 1500 litres a month means R37,500 saving a month in diesel costs”. My line costs(25Kva) vs a 100kVA line feed saves me R26 000 per year on line costs only,” Davidson said.
