Skip to main content

On-farm energy efficiency

With the recent hike in energy costs, it is not surprising that more farmers are carrying out energy audits to identify how they can make savings. The Sustainable Energy Authority of Ireland's (SEAI's)

Support Scheme for Energy Audits (SSEA) will offer SMEs a €2,000 voucher towards the cost of a high-quality energy audit. In most cases, this will cover the total cost of the audit. The annual energy spend must exceed €10,000. Application to the scheme is easy, with automatic approval for eligible businesses. Details can be found on the website. 

Higher electricity and fossil fuel prices bring more opportunity to improve the viability of renewable-energy systems. Previously, some projects may not have been feasible, but now they are often a no-brainer. Energy efficiency goes hand in hand with on-farm carbon reduction. Energy audits are already being used by some processors to help deliver net-zero targets across their supply chains. 

General audit findings on dairy farms

1. Installation and maintenance of the most modern equipment

The three biggest consumers of energy on a dairy farm are the vacuum pump, the water-heating system and the milk-cooling system. Vacuum pumps are sized with enough reserve capacity to maintain constant pressure when claws are changed or knocked off. However, there are extended periods of time between milking and cleaning the udder when vacuum-pump requirements are much lower. In the older systems, the vacuum pump continues to run at full speed, which is wasting energy. Modulating the vacuum-pump speed with a variable speed drive (VSD) controller can save up to 50 per cent less energy or units of electricity (kWh) in the milking process.
Meanwhile, the function of a variable-speed milk pump ensures a slower and more consistent flow of warm milk through a plate pre-cooler. The warm milk is exposed to cold water for longer, maximising the exchange of heat. This is much more effective than a stop-start process, and it reduces the electrical load on the refrigeration system.

2. Load shifting and peak saving

This year has been a significant year for solar PV, especially for rooftop solar. With the practical elimination of the requirement for planning permission, a new simplified grid connection policy, revisions to VAT regulations and the introduction of a 60 per cent grant aid towards the cost of solar PV system, there has never been a better opportunity to invest in this technology on your farm and farmhouse. However, milking often takes place outside peak solar hours, so dairy farmers need to think creatively to make the most of this cheap energy.
A solar diverter is a device through which any solar power not being used in your farm is diverted to an electrical appliance, generally an immersion heater in your hot water and/or an electric heater. The use of water heaters and ice-builders can be used as thermal energy storage systems and are cheaper than using batteries. Many farmers operate ice-builders or immersion heated systems at night to take advantage of night rate tariffs, but greater savings can be made by charging them during the day using free solar power.
The efficient use of solar PV can be increased where hot water and ice water systems are large enough for an evening and morning-after milking. This will save having to run systems twice per day and will maximise solar energy usage on the farm. 

3. Utilising pre-coolers to cut milk temperature 

Pre-cooling of milk in-line by well or mains water before it enters the bulk-milk tank has a number of advantages. The temperature of the milk will be reduced and can save the refrigeration compressors from using a considerable amount of electricity. A plate cooler fitted to the discharge side of the milk pump is the most popular pre-cooling system mainly due to its high efficiency and compactness. Using a pre-cooler milk can reduce the temperature by about 15oC before it enters the tank. The water can then be collected for parlour washing or as drinking water for the cattle to minimise waste.

4. Renewable energy

Solar PV is definitely the most suitable investment for most dairy farms, regardless of the herd size. All dairy farms have a large surface area on their shed and in the absence of planning-permission requirements the barriers to installation are low. PV is also scaleable – the larger the herd, generally the more roof space for panels. Typically, dairy farms can save 30-50 per cent in energy costs by installing solar panels, and systems will pay for themselves within three to four years, depending on the contract with your electrical provider.
Savings will also be made by replacing older fluorescent lighting with LEDs in both parlours and in the cow cubicles. Upgrading fluorescent tube lighting with modern LED battens can cut electricity use by 60 per cent.

Microgeneration and Solar PV

Farmers who are eligible for the grant under the Solar Capital Investment Scheme are expected to see payback periods of two to four years. There are challenges in rural areas in terms of grid capacity which can limit the export capacity on some farms. The other Targeted Agricultural Modernisation Scheme (TAMS) limiting factor is that the solar survey will determine the previous electricity use. The Department of Agriculture, Food and the Marine (DAFM) assumes that a typical PV array will generate 1,000kWh (units) of electricity per annum.  A farmer who can demonstrate that their previous electricity bills for both the house and farm was, for example, 25,000kWh would be permitted to apply for 25kW of PV generated electricity through the inverter.  This assumes they have a mini-generation grid connection to match and that all other terms and conditions are met. TAMS recipient farmers are not prohibited from selling excess electricity back to the grid at times when they cannot use it. They can avail of the Clean Export Guarantee (CEG) market rate which is available from their electrical utility. 

Tax considerations

For non-domestic installations, the cost of panels is eligible for accelerated capital allowances, therefore the expenditure can be offset against the business’ taxable profits. One hundred per cent of the installation cost can be offset against profits in the year the spending is incurred. Ensure the equipment model is eligible for accelerated capital allowances by checking the Triple E product register before making purchase. This is relevant to all the aforementioned renewable technologies and energy efficient equipment including LED lighting. If energy is generated surplus to the requirements of the farm business and is sold to the national grid, this is treated as taxable income.