02 July 2025
Soaring energy prices and how they impact on the cost of production on Welsh dairy farms has reinforced the value of investing in an energy audit.
An audit identifies where savings can be made - in some systems this can add up to several thousand pounds a year.
During a recent series of Farming Connect on-farm events that focussed on farm energy costs and consumption, NFU Energy project engineer Jonathan Sandercock advised farmers how audits worked and where they could make gains.
An energy audit starts with a farm visit followed by a report that offers solutions on how that farm can capture energy savings.
This might include modernising energy intensive systems, or investing in renewables and using the energy produced at peak demand.
One of the most common mistakes picked up during an audit is incorrect application of technology – for example using the wrong type of slurry separator to produce ‘green’ bedding for cow cubicles.
“One farmer we visited was using a roll press that generated material with a dry matter content of 20% but to produce green bedding he required a screw press that would increase this to 40% therefore the bedding he was producing was too wet and that’s why the system wasn’t working for him,’’ Jonathan explained.
“The system was not fit for its purpose and was costing a lot of energy to run for no real gain.’’
An audit typically costs £1,500 - £2,000 and is only financially sensible in systems with high energy consumption, he added.
“The energy use on a sheep farm is vastly different to that of a dairy farm - a sheep farm might only spend £2,000 a year on energy therefore an audit won’t be good value for money, but if a dairy farm is paying £40,000 a year and an audit identifies savings of 10% that would reduce spend by £4,000 a year.’’
The three biggest consumers of energy on a dairy farm are the water-heating and milk cooling systems and the vacuum pump.
In older systems, a pump will run at full speed when that function is not required which means that energy is being consumed unnecessarily.
Jonathan advised that modulating pump speed with a variable speed controller can reduce energy use by up to 50%.
Also, a variable speed milk pump will create a slower and more consistent flow of warm milk through a plate pre-cooler, exposing it to cold water for longer and maximising heat exchange.
Jonathan said this was more effective than a stop-start process with a float switch, and it reduced load on the refrigeration system.
Heat recovery is another simple system which more dairy farms should utilise, he recommended.
This works by reusing the heat that's normally wasted by the refrigeration system; instead of allowing that heat to escape into the air, it redirects it to heat water, cutting the energy needed for washing by 40-50%.
More farms are investing in renewable energy as it offers good solutions to reducing costs, with photovoltaic (PV) solar panels a cost-effective option in a dairy farming situation.
“The energy crisis in the last five years has opened farmers’ eyes to how susceptible they are from price spikes and not in control of their costs when they rely on buying that energy in,’’ said Jonathan.
Solar panels can typically reduce energy costs on a dairy farm by 30-50% and those savings will provide a five-to-seven-year payback period.
However, as milking is often done at times of the day when there is little sunshine, Jonathan said systems need to be adapted to make best use of it, through water heaters and ice-builders for example.
By installing these with capacity for two milkings, solar energy usage can be further exploited.
Also, reducing the temperature of the milk before it enters the bulk tank by installing a pre-cooler will mean refrigeration compressors use less electricity.
Being more energy efficient also aligns with environmental efficiency as on-farm energy generation reduces reliance on fossil fuels, says Farming Connect’s carbon specialist officer, Dr Non Williams.
It can help farms reduce their carbon footprint by utilising the energy produced.
Renewable energy options, such as AD plants, have secondary benefits too.
“If a nutrient-rich digestate is produced along with the renewable energy it can be applied on farmland and potentially reduce greenhouse gas emissions associated with purchased inputs due to less fertiliser requirements,’’ said Non.
The digestate can also aid nutrient cycling, help to build soil organic matter, and consequently, organic carbon levels.
“With many renewables and technology options, there are a lot of ‘ifs’ and ‘buts’ but if they complement a system they can have many benefits,’’ Non added.
However renewable energy cannot always be used as part of the calculations around a farm’s own carbon emission reductions.
“If farmers are exporting, that is selling the energy they are producing from renewables, this carbon benefit is assigned to the energy sector due to how carbon is accounted for in the UK’s Greenhouse Gas Inventory nationally,’’ Non explained.