P.W.G. Groot Koerkamp

Energy demand on dairy farms in Ireland

Reducing electricity consumption in Irish milk production is a topical issue for 2 reasons. First, the introduction of a dynamic electricity pricing system, with peak and off-peak prices, will be a reality for 80% of electricity consumers by 2020. The proposed pricing schedule intends to discourage energy consumption during peak periods (i.e., when electricity demand on the national grid is high) and to incentivize energy consumption during off-peak periods. If farmers, for example, carry out their evening milking during the peak period, energy costs may increase, which would affect farm profitability. Second, electricity consumption is identified in contributing to about 25% of energy use along the life cycle of pasture-based milk. The objectives of this study, therefore, were to document electricity use per kilogram of milk sold and to identify strategies that reduce its overall use while maximizing its use in off-peak periods (currently from 0000 to 0900 h). We assessed, therefore, average daily and seasonal trends in electricity consumption on 22 Irish dairy farms, through detailed auditing of electricity-consuming processes. To determine the potential of identified strategies to save energy, we also assessed total energy use of Irish milk, which is the sum of the direct (i.e., energy use on farm) and indirect energy use (i.e., energy needed to produce farm inputs). On average, a total of 31.73 MJ was required to produce 1 kg of milk solids, of which 20% was direct and 80% was indirect energy use. Electricity accounted for 60% of the direct energy use, and mainly resulted from milk cooling (31%), water heating (23%), and milking (20%). Analysis of trends in electricity consumption revealed that 62% of daily electricity was used at peak periods. Electricity use on Irish dairy farms, therefore, is substantial and centered around milk harvesting. To improve the competitiveness of milk production in a dynamic electricity pricing environment, therefore, management changes and technologies are required that decouple energy use during milking processes from peak periods.

Investment appraisal of technology innovations on dairy farm electricity consumption

The aim of this study was to conduct an investment appraisal for milk-cooling, water-heating, and milk-harvesting technologies on a range of farm sizes in 2 different electricity-pricing environments. This was achieved by using a model for electricity consumption on dairy farms. The model simulated the effect of 6 technology investment scenarios on the electricity consumption and electricity costs of the 3 largest electricity-consuming systems within the dairy farm (i.e., milk-cooling, water-heating, and milking machine systems). The technology investment scenarios were direct expansion milk-cooling, ice bank milk-cooling, milk precooling, solar water-heating, and variable speed drive vacuum pump-milking systems. A dairy farm profitability calculator was combined with the electricity consumption model to assess the effect of each investment scenario on the total discounted net income over a 10-yr period subsequent to the investment taking place. Included in the calculation were the initial investments, which were depreciated to zero over the 10-yr period. The return on additional investment for 5 investment scenarios compared with a base scenario was computed as the investment appraisal metric. The results of this study showed that the highest return on investment figures were realized by using a direct expansion milk-cooling system with precooling of milk to 15°C with water before milk entry to the storage tank, heating water with an electrical water-heating system, and using standard vacuum pump control on the milking system. Return on investment figures did not exceed the suggested hurdle rate of 10% for any of the ice bank scenarios, making the ice bank system reliant on a grant aid framework to reduce the initial capital investment and improve the return on investment. The solar water-heating and variable speed drive vacuum pump scenarios failed to produce positive return on investment figures on any of the 3 farm sizes considered on either the day and night tariff or the flat tariff, even when the technology costs were reduced by 40% in a sensitivity analysis of technology costs.

Gaseous Emissions From Aviaries And Nitrogen And Phosphorus Losses In The Outdoor Run Of Organic Laying Hens

Emissions and losses from animal production systems cause substantial environmental impact, e.g. eutrophication, acidification and global warming. The objectives of this study were to assess the year round emissions of ammonia (NH3), nitrous oxide (N2O), and methane (CH4) from commercial aviary systems with organic laying hens and to determine the level and variation of the total mass, and load of nitrogen (N) and phosphorus (P) excreted into the outdoor run of three commercial organic laying hen farms. Emissions were computed from the ventilation rate (CO2 mass balance) and gas concentrations. N and P losses were calculated from number of hens, mass and content of excrements in the outdoor run. Mean emission per hen was 410 mg d-1 for NH3, 3.12 mg d-1, for N2O and was 81.7 mg d-1 for CH4. Mean predicted emission of NH3 per hen on the first day after manure removal was 298 mg d-1, and increased by 5.47% d-1. Using aviary systems in organic laying hen husbandry instead of single-tiered systems has the potential to reduce emissions of NH3, N2O, and CH4. Mean percentage of hens outside was 1.7% on farm 1, 16.0% on farm 2 and 7.1% on farm 3 and. On all farms load of N and P heavily exceeded the fertilization standard of 170 kg ha-1 y-1 and decreased exponentially with increasing distance from the hen house, due to an also exponentially decreasing hen density.

Environmental consequences of segregating pig urine and feces - a life cycle perspective.

The aim of this study was to assess the environmental consequences of segregating pig urine and feces under the animal house compared to conventional manure management. The environmental impact was assessed by using life cycle assessment. System boundaries encompassed the stages: in-house management, outside storage, transport and field application. Five impacts were evaluated: climate change (CC), terrestrial acidification (TA), marine eutrophication (ME), particulate matter formation (PMF), and fossil fuel depletion (FFD). Results showed a decrease for CC (up to 82%), TA, and PMF (up to 49%) when urine and feces were segregated, whereas ME increased (up to 11%). It was concluded that segregation of pig urine and feces reduces the environmental impact compared to a conventional manure management system and that the liquid state of the feces is essential for further improvement of the environmental performance of manure management with segregation.