Farmers have been advised to identify the least energy-efficient areas on their farms before adopting renewable technologies such as solar PV or heat pumps.
Rectifying areas where farmers are losing heat or wasting electricity should be the first step farmers take to be become more energy efficient on their farms.
That is according to energy and rural development specialist at Teagasc, Barry Caslin who recently discussed viable energy options for farmers at the Irish Pig Health Symposium 2023.
Energy efficiency
Any company in Ireland, he said, is entitled to a grant by the Sustainable Energy Authority of Ireland (SEAI) which covers the cost of an audit to assess a farm’s energy efficiency.
The idea of the audit is to have more information which is needed to improve on-farm energy usage and make investments in energy-saving measures and renewable technologies, he said.
The key points in energy efficiency are looking at enclosed creep areas for the thermal environment to be better regulated whereby the heating system can be managed more easily.
There is less heat on the sow as well, which means she is going to be heating more, he said explaining that a cooler sow would be heating more using those enclosed creep areas.
Speaking about more energy-efficient lighting, Caslin said that by switching from tungsten to fluorescent bulbs, the energy used per pig produced could be reduced from 2-4kWh to 0.2-0.4kWh.
This reduction would be even more significant using LED lights, he added. By using more efficient pumps, the energy per pig produced could be reduced from 6kWh to 3kWh.
In terms of ventilation systems and fans, Caslin highlighted the importance of maintaining fans in a clean condition as their efficiency can drop by 20% if they are not being cleaned.
Solar PV
Solar panels need daylight rather than sunlight, Caslin said. Thus, a solar PV system would generate approximately five times more electricity in May/June than in December/January.
Speaking about the potential of solar PV usage on Irish pig farms, he said the best return of investment is to use a generator for electricity for self-consumption on the farm.
Up to 50kW systems, this is considered microgeneration for which no planning permission is required unless the farm is located in a solar safe guarding zone e.g., near an airport, he said.
Monocrystalline panels are the most expensive but also the most efficient solar panels of which there are two types – glass foil and glass on glass, Caslin explained.
The price difference between the glass foil panels and the glass-on-glass ones, which are a more premium product, is 15-20%, he added. However, there are also different rates of degradation.
Caslin explained that the amount of electricity that is generated by a solar PV system continues to decline on an annual basis from the year the panels were bought.
The rate of degradation for glass foil panels ranges from 0.55%-0.70% per year, compared to glass-on-glass panels which electricity generation drops by 0.34% per year in kWh of production.
Panels should be positioned at 35° facing south, south west, or south east. Sometimes, he said, this side might be shaded by trees and farmers might need to opt for a ground-mounted system.
Standard solar panels are 1.66m x 1m at 320/400W per panel or 0.32kW/04.kW respectively. In the midlands, Caslin said, each kW would generally produce 900-1,000kWh of electricity per year.
800-sow pig farm
Example
- Annual electricity use 325,000kWh
- Day rate for electricity €0.25c/kWh, night rate €0.15c/kWh
- Annual electricity bill €119,190 plus VAT
- Main uses: farrowing and heat pads (30%); manure processing (20%); feed and water delivery (15%); lighting (15%); ventilation system (10%); power washing (5%); miscellaneous (5%)
- Area roof space available for solar PV 1,200m2
- ESB connection: three-phase
- Maximum import capacity 100 kVA
- Location of transformer: within 75m
- Battery storage: not suitable
- Accelerated Capital Allowance (ACA): 100%
- System generates 109,200kWh per annum
- System requires 975m2 of roof space.
Using this example, equipment costs for a 130kWp system would be at €137,750, minus grant aid available under the Solar Capital Investment Scheme of €54,000 would result in net costs of €83,750.
A payback period of three years would be achieved in this case at the 60% grant rate under the Targeted Agriculture Modernisation Schemes (TAMS), Caslin said.
The 130kWp solar PV system on an 800-sow farm would lead to electricity savings of €27,300 and would offset 38t of carbon dioxide (CO2) per annum, the energy and rural development specialist said.