Dr Natalie Meades: IBERS, Aberystwyth University.
- Embracing renewable energy technologies on farm has the potential for farms to become more diversified, reduce environmental emissions and become more sustainable.
- The adoption of renewable energy technologies provides an opportunity for farms to lower energy costs through complete or partial energy self-sufficiency. Moreover, renewable energy has the potential to generate additional revenue for farms by selling surplus electricity to the grid, renting land to investors or through joint ventures with investors.
- Renewable energies such as solar, wind and water are largely dependent on climate and geography, as such certain technologies may not be suitable for all enterprises and therefore careful planning and selection is needed.
Introduction
Climate change is one of the greatest threats to life on Earth and can be defined as the gradual change in the Earth’s climate and geography resulting in the warming of the Earth. Greenhouse gasses such as methane, nitrous oxide, carbon dioxide and fluorinated gases when emitted into the Earth’s atmosphere, trap heat from sunlight and contribute to the warming of the Earth. This is a perfectly natural process and is essential for maintaining the Earth at a temperature conducive for life. However, anthropogenic activities such as the burning of fossil fuels and certain land management practices have amplified this process resulting in global warming and climate change. As such, the UK government along with other countries are developing targets and strategies to mitigate, prevent, stop and adapt to climate change. One way in which the UK Government including the Welsh Government is aiming to do this is by achieving net zero greenhouse gas emissions by 2050. This involves changing the ways in which we currently utilise resources and manage the land so that greenhouse gas emissions are equal to greenhouse gas sequestration, as such an equilibrium is achieved.
The agricultural industry is currently receiving attention regarding its use of natural resources and the effects of certain land management practices on the environment and on nature. To put this into perspective, ‘The Department for Environment Food and Rural Affairs’ (DEFRA) estimated that in 2019 the UK agricultural industry contributed to; 10% of total greenhouse gas emissions, 68% of total nitrous oxide emissions, 47% of total methane emissions and 1.7% of total carbon dioxide emissions in the UK for that year. Moreover, according to the ‘Agriculture and Horticulture Development Board’ (AHDB) 56% of agricultural greenhouse gasses are typically produced from methane, 31% from nitrous oxide and 13% from carbon dioxide. As a result, greenhouse gas production within the industry is a topic of conversation and the ‘National Farmers Union’ (NFU) has set the target for the UK and Welsh agricultural industries to achieve net zero by 2040.
Renewable Energy
Renewable energy as discussed in a previous technical article can be defined as energy that is generated from a resource that is not depleted when used. This includes energy generated from sources such as; solar, wind, hydroelectric and bioenergy. Of the renewable energies currently utilised in Wales, approximately 76% of renewable energy generates electricity and 24% heat. Depending on type, such energies are either described as being clean or green due to having no or low green-house gas emissions. This article will primarily focus on renewable energy and electricity, in which the Welsh Government has set a target for Wales to meet the equivalent of 70% of its electricity demand from renewable energy resources by 2030.
Renewable Energy and Agriculture – what are the opportunities?
Currently, the agricultural industry is heavily reliant on fossil fuels such as oil, natural gas and a small quantity of coal to; power machinery, for electricity to power equipment and lighting and to heat, dry and cool depending on the farming enterprise. However, fossil fuels are non-renewable finite resources which emit greenhouse gasses when burnt. Moreover, the cost-of-living crisis in the UK has seen a steep increase in energy prices and standing charges, thereby influencing general farm and variable costs, which therefore affect margins. As such, there is need and drive to reevaluate the ways in which energy is sourced and utilised on farm for both environmental and economic benefit.
The integration of renewable energy on farm in either complete or partial replacement of non-renewable energies provides an attractive alternative to fossil fuels. Depending on type, infrastructure and energy generating capacity, the use of renewable energies on farm provides an opportunity for farms to become more diversified, reduce environmental emissions and potentially become energy self-sufficient and therefore lower energy costs. This could be particularly advantageous for enterprises that use high volumes of electricity such as the dairy and poultry industries. Not only that, for remote farms which do not have access to the grid the use of renewable energies could provide an opportunity to receive electricity to buildings and reduce the reliance on fossil fuel powered generators. Moreover, the integration of renewable energy onto farms is outlined within the proposed actions of the Welsh Sustainable Farming Scheme, as part of the scheme characteristics to ‘reduce on farm emissions and maximise carbon sequestration ‘by ‘adopting energy efficiency practices and producing renewable energy on-farm’.
The installation of renewable energy technologies for small-scale low carbon generators, has the potential to generate additional revenue, in which surplus energy can be sold to the grid through the Smart Export Guarantee, depending on connection availability and distance to the grid. Previous opportunities to generate revenue have included, the Feed In Tariff, however this closed to new applicants in 2019. Other potential revenue opportunities include, investing companies that look to rent land from farms to install their technologies or to collaborate with farms in joint ventures. This may seem an attractive option, as direct investment of capital by farms may not be needed. However, landowners in the UK may be hesitant to rent land to large companies, regarding the effects some experienced with the alteration of the Electronics Communication Code in 2017.
The different renewable energy options available to farms will be outlined in the next section. It must be noted, that farms have a number of options available to them and are not just restricted to one technology. In fact, having a mixture of renewable energy technologies on farm can be beneficial and useful should one be working more effectively than the other.
What Technologies are Available for Use on Farm?
Solar photovoltaic
Solar photovoltaic (SPV) technology involves the conversion of solar radiation into electricity within SPV panels. Such technology is increasing in popularity and becoming more accessible and affordable as the technology develops and advances. The efficiency and success of SPV is largely down to geographical location and as such SPV panels should ideally be south or near south facing and at the most appropriate angle for maximum solar capture. Electricity generated from SPV technology can be used during the day as it is generated or depending on the technology; stored in batteries for later use or sold back to the grid thereby generating revenue. There is little maintenance required with solar panels other than ensuring they are free of dust, leaves and bird excrement that could potentially decrease solar capture, however seeing as the Welsh climate has high rainfall this is rarely an issue. It must be noted that SPV panels don’t have an infinite life span, where a study estimated the degradation rate of field aged solar panels to be 0.8-1.8% per year and for the average lifespan of a SPV panel to be approximately 25 years depending on the technology.
SPV panels can be fitted onto the rooftops of agricultural barns, sheds, glasshouses or on water and often require planning permission from local authorities. Such systems are extremely attractive as they do not require additional space on the ground. Moreover, inverters associated with SPV panels are typically housed within soundproof casing and as such have limited noise pollution so may be suitable for location near to urban and residential
areas depending on social views. SPV panels can also be fitted on the land and on a much larger scale as solar farms with permission from planning authorities. However, many argue that land utilised solely for energy production directly competes with agricultural production and therefore negatively effects food security, farming culture and tradition. As such, an integrated system known as agrophotovoltaic could be implemented on farm in which livestock and/ or crop production coincide with SPV technology. Such systems have demonstrated great benefits and are estimated to increase the productive capacity of the land by 60-70%.
Livestock agrophotovoltaic systems are often restricted to sheep production systems, due to the size of cattle and the natural curiosity of goats to climb being potentially damaging to SPV panels. Research as to the effects of livestock agrophotovoltaic systems on animal performance and pasture quality are limited. However, a two-year study conducted at Oregan University compared recently weaned Polypay lambs grazing in open pastures to lambs grazing on pastures with SPV panels, in which pasture was partially or completely shaded by the panels. The results of the study demonstrated lambs grazing under the panels to have no difference in live weight gains or live weight production when compared to lambs grazing open pasture. Interestingly, when pasture quality and yield were measured, it was found that pasture shaded by the solar panels had a lower density and therefore lower yields in comparison to open pasture, however this was outweighed by the nutritional quality of the shaded pasture which was greater in comparison to open pasture. Moreover, SPV panels have been demonstrated to have positive effects on improving the welfare of sheep in which they provide shelter from the elements and shade from direct sunlight thereby helping to reduce the likelihood of ailments such as heat stroke.
Crop agrophotovoltaeic systems involve SPV panels located on stilts in which crop production occurs around or directly beneath panels. Panels can be ground mounted or at such a height that agricultural machinery can successfully pass underneath. Research on the effects of such systems have mainly been conducted in arid and semi-arid areas on plants such as; lettuce, cucumber, tomato, wheat, maize and potatoes to name a few. A literature review on crop agrophotovoltaic systems weighed up the benefits, challenges and opportunities associated with such systems. SPV panels have demonstrated beneficial effects in creating canopies which shade and protect plants from intense solar radiation and are therefore thought to stabilise yields in hot and drought conditions. However, it must be considered that not all agricultural plants are tolerant to shading and therefore plants should be carefully selected for use in such systems to limit loss of yield. There is still much more to learn and more research is required regarding the effects of integrating this technology with other agricultural plants and in temperate climates.
Panels have also demonstrated beneficial effects on the soils beneath them, in which soils have been observed to have greater moisture retentions and improved water use efficiency due to reduced evapotranspiration. This could be especially useful over hot summer months regarding water use and irrigation demand. Conversely, heavy rainfall may result in increased runoff from panels and result in localised soil erosion and the formation of gullies surrounding panels and therefore damage crops. However, the use of solar tracking technology has demonstrated beneficial effects in overcoming such challenges in which, solar exposure to the panel can be maximised, shade exposure of plants reduced and rainfall distributed. Although research into this area is limited, early studies also suggest the shading of pasture by SPV panels to not negatively affect biodiversity. A study demonstrated that although the onset of floral blooms were delayed by shading, this did not affect the visitation of flowers by insects.
Wind
Wind energy is another popular form of renewable energy and was responsible for producing 24% of the total electricity in the UK in 2020. This type of energy is dependant on the weather, although it is possible to have wind over 24 hours and therefore is not restricted to certain times of the days as with SPV technology.
Wind drives the propellers of a wind turbine generating kinetic energy which is then converted to mechanical energy and generates electricity. As such, they are most efficient in offshore environments or onshore in high up exposed areas with limited tree cover and high wind capacity. Electricity can either be used directly as it is generated, stored in batteries for later use or sold to the grid generating revenue depending on type and scale.
When many think of wind energy, wind farms are generally considered. Turbines on such sites are a significant investment and will often involve investors. Turbines can be up to 150 m in height and due to their vertical scale do not take up a lot of ground space, allowing for agricultural activities to continue around them. However, consideration is needed regarding the accessibility of land for initial installation and regular access requirements to sites for maintenance. On a smaller scale, wind energy can be utilised via a singular turbine on farm or as small-scale turbines which are typically < 50 m in height and have the potential to generate between 5 – 50 KW depending on type. On an even smaller scale, rooftop turbines could be installed depending on energy demand.
The planning, application and installation process for wind turbines is long and detailed. In Wales, onshore wind energy projects of more than 10 MW capacity are classified as developments of national significance and approval of applications are granted by Welsh Ministers, whereas smaller projects are approved by local authorities. Some of the major hurdles to consider when applying for planning permission are the social perceptions of the local communities, in which wind turbines are often seen as eye sores and many have concern regarding noise pollution and the devaluation of property. As a result, they are not suited close to residential areas. From an environmental perspective, there is also concern regarding the effects on wildlife. For example, birds colliding with blades, habitat loss and disturbance. However, a study suggested painting one of the blades of a turbine black to have the effect of reducing bird fatalities by >70% in comparison to non-painted turbines.
Hydroelectric
Hydroelectric energy is responsible for approximately 5.2% of renewable energy generation in Wales and involves the generation of electricity from the movement of water. The flow of water drives a turbine converting kinetic energy into mechanical energy which is then converted into electricity. Electricity can be used directly, stored in a battery for later use or surplus sold to the grid depending on technology and location.
Hydroelectric technologies on farms tend to be of a small scale generating less than 100 kW of electricity. The majority of technologies on farms utilise the natural flow of water from rivers or streams, however some rely on the storage of water in small reservoirs or mill ponds. Provided they are built correctly, hydroelectric power has little effect on local ecosystems. However, hydroelectric energy is largely dependent on the constant flow of water, and therefore a decrease in efficiency may be seen when water levels are low. The initial cost of installation is high and following the removal of support schemes in Wales such as the Feed In Tariff and Renewables Obligation the number of new hydroelectric projects has declined since 2017. However, the technology lasts for a long period of time with many suggesting this outweighs the initial cost.
Summary
The integration of renewable energy technologies such as solar, wind or hydro-electric power provide an opportunity for the gradual or complete replacement of fossil fuels on farms, thereby providing a pathway for farms to become more sustainable. Incorporating renewable energy on farm can help to reduce energy costs, increase the productive value of the land and provide revenue opportunities by; selling surplus electricity to the grid, renting land to investing companies or via collaboration with investing companies in joint ventures. To increase the incentive for uptake of renewable energy technologies on farms, greater support, funding, grants and access to demonstration sites could be implemented. It must be noted that not all renewable technologies will be suited to all farm systems and types, therefore careful selection and planning is needed. Likewise, the renewable energies described in this article rely on natural resources such as solar, wind and water which are largely dependent on geography and climate. As such, there may be times in which backup energy sources are required.