Niamh Power

Residential solar photovoltaic (PV) is a significant contributor to sustainable energy systems. Early adopters can provide insights into its effectiveness and lessons for policymakers and grid operators. This study investigates electricity use in 59 early-adopter PV homes in Ireland, integrating household survey data with high-resolution smart meter and PV system data. The dataset enables analysis of technology adoption, load profiles and self-usage, but data standardisation was challenging due to 12 different PV data sources, 25 file formats, and seven temporal resolutions, underscoring the need for harmonised data protocols. Results show these homes differ markedly from national averages: median annual electricity use was 8,394 kWh, 2.8 times the Irish median, and baseloads were less than half (~250 W) expected from national load profiles. Fewer than 10% of households peaked in the evening (5-7 p.m.), while 53% peaked overnight, reflecting EV charging, battery operation, and tariff-driven load shifting. Average self-consumption rate (SCR, 57%) was above the 30% assumed in fuel savings calculations but below the 100% used in building energy rating assessments. In bivariate tests, battery ownership was associated with ~+17 pp higher SCR while smart tariffs were associated with lower SCR and Self-Sufficiency Rate (SSR) (~-16pp and 12pp respectively). EV ownership was linked to materially higher annual use and higher peak import, but not to higher SCR, implying sub-optimal charging alignment with PV output. The findings highlight to policymakers opportunities and risks in scaling PV adoption, particularly the importance of aligning flexible loads with renewables to maximise SCR/SSR and reduce peaks.

Phosphorus (P) is an essential growth-limiting nutrient that cannot be synthetically produced. Mineral P fertilisers are typically applied to crops to sustain modern farming practice and food production. These fertilisers are generally derived from finite phosphate ore, for which there is much concern over long-term sustainability. To address these concerns, various technologies have been developed to recover P from municipal wastewater treatment plants. One product recovered from these processes is struvite, which is a precipitate formed of magnesium, ammonium, and phosphate. To analyse the fertilisation value of the recovered struvite, field trials were conducted on perennial ryegrass (Lolium perenne) over three growing seasons, analysing the dry matter yield of recovered struvite fertiliser. The trial was based on a three-crop silage system designed to mimic typical Irish agricultural practice. This research highlights that recovered struvite as a fertiliser provides additional benefits including increasing the soil P levels. The struvite test case produced a statistically significantly increased soil P level from the baseline of Morgan’s extractable P content of 6.4 mg/L to the optimum Morgan’s soil P level of 11.13 mg/L. The findings of this research provide insight into the added benefits of recovered struvite fertiliser as a sustainable renewable P fertiliser.

Anaerobic digestion (AD) has been recognised as an effective means of simultaneously producing energy while reducing greenhouse gas (GHG) emissions. Despite having a large agriculture sector, Ireland has experienced little uptake of the technology, ranking 20th within the EU-28. It is, therefore, necessary to understand the general opinions, willingness to adopt, and perceived obstacles of potential adopters of the technology. As likely primary users of this technology, a survey of Irish cattle farmers was conducted to assess the potential of on-farm AD for energy production in Ireland. The study seeks to understand farmers’ motivations, perceived barriers, and preferred business model. The study found that approximately 41% of the 91 respondents were interested in installing AD on their farming enterprise within the next five years. These Likely Adopters tended to have a higher level of education attainment, and together, currently hold 4379 cattle, potentially providing 37,122 t year⁻¹ of wastes as feedstock, resulting in a potential CO₂ reduction of 800.65 t CO₂-eq. year⁻¹. Moreover, the results indicated that the primary consideration preventing the implementation of AD is a lack of information regarding the technology and high investment costs. Of the Likely Adopters and Possible Adopters, a self-owned and operated plant was the preferred ownership structure, while 58% expressed an interest in joining a co-operative scheme. The findings generated provide valuable insights into the willingness of farmers to implement AD and guidance for its potential widespread adoption.