Livestock sector is a significant energy consumer of different energy carriers. According to Eurostat, about 158 million tons of cow milk is produced annually and on average, each kg of milk produced requires 3.42 MJ of energy inputs. From that number, about 74% accounts for feed production, 9% for diesel fuel used mainly for manure management, and 17% for other demands such as electrical energy for milking systems, feeding, lighting and ventilation. More specifically, it is estimated that the on-farm electrical consumption is associated with milk cooling (36%), milk harvesting (32%), water heating (23%) and water pumping (9%). There is a range of factors affecting the final results, the most important of which being the farm location, infrastructure, production system and type of milking system. Renewable energy sources and energy efficiency measures and technologies in combination with energy conservation practices provide a unique opportunity for farms to reduce energy consumption and produce their own clean energy to become partially or even totally self-sufficient. Solar energy, bioenergy, heat pumps, wind energy, geothermal energy and organic Rankine cycle applications hold great potential to be applied to all types of farms, covering an extremely wide range of energy needs. Within RES4LIVE, in a dairy pilot farm smart management and control will be utilized to efficiently control the heat and electricity production systems, and regulate the barn ventilation. A developed biogas upgrading unit will be also demonstrated on an existing biogas digester, as well as a retrofitted tractor for biomethane use. Moreover, an electric tractor will be used, charged by the electricity produced by photovoltaic thermal hybrid solar collectors.

The production of 1 kg of eggs requires about 20.5 to 23.5 MJ of energy inputs and in all cases at least 50% of all energy inputs are associated with the production of feed. On-farm energy demand is mainly covered by electricity (55%), followed by diesel fuel (33%) and LPG (12%). Electrical energy consumption can be further classified according to its specific use into ventilation (33%), automatic feeding (15%), lighting (15%) and packaging (14%); while diesel and LPG are used mainly for heating, but also incineration of dead layer birds.

Renewable energy sources and energy efficiency measures and technologies in combination with energy conservation practices provide a unique opportunity for livestock farms to reduce energy consumption and produce their own clean energy to become partially or even totally self-sufficient. More specifically, solar energy can be utilized in all types of farms, being able to put up for both electricity and heating needs. Heat pumps’ potential is focused on applications that allow their coupling with photovoltaic-thermal hybrid solar collectors or geothermal units, especially in confined animal buildings, like poultry and pig farms. Wind energy constitutes a promising renewable energy sources for confined buildings, which have high electrical energy demand mainly for ventilation and lighting.

Within RES4LIVE, photovoltaic panels will be installed to fully cover the needs of an experimental farm for egg production. A heat pump and inverter fans for ventilation will regulate its indoor environment along with a smart control system, which will also manage the photovoltaic power production for maximizing the self-consumption.

Agricultural machinery is almost universally powered by diesel fueled internal combustion engines, however, several farm machinery manufacturers have conducted research on their electrification and have showcased their electric tractor prototypes at various exhibitions. Conventionally sized field work tractors with battery electric drives offer: (a) reduced emissions, (b) increased driveline efficiency, (c) torque reserve, (d) lower fuel import dependency, (e)increased controllability and (f) use of renewable energy.

Electric tractors can be either converted from conventional tractors, applying the appropriate modifications, or designed and manufactured from the beginning as electric vehicles. Currently the most applied concept for converting tractors is the replacement of the internal combustion engine with an electric drivetrain, without affecting the vehicle’s structure. Electric vehicles are classified into Battery Electric Vehicles (BEV) and Hybrid Electric Vehicles (HEV). HEVs use both an internal combustion engine and an electric motor and one of them acts as the primary power source. As current energy storage capacity of batteries is generally low to support several hours of heavy work, using an e-tractor would lead to a trade-off between either a longer working day for the driver due to the recharge time and reduced working time in the farm in total. At the moment two ways to overcome these limitations are autonomous drive systems and rapid recharging systems. Autonomous drive could allow the operation for more hours compared to a manned tractor, while rapid recharging could minimize the recharging time. RES4LIVE aims to demonstrate and assess the use of an e-tractor for on-farm daily tasks in one of its pilot farms.

Livestock farms consume a considerable amount of thermal and electrical energy. Photovoltaic thermal (PVT) collectors convert solar radiation into usable thermal and electrical energy, combining photovoltaic (PV) solar cells generating electricity, with a solar thermal collector, which transfers the excess heat from the PV module to a heat transfer fluid generating temperatures up to 80°C. Concentrating PVTs can reach temperatures up to 140°C. In a solar PV panel, photovoltaic cells typically reach an electrical efficiency (referring to the portion of energy in the form of sunlight that can be converted into electricity) between 15-20%, while the largest share of the solar spectrum (65-70%) is lost as heat, increasing the temperature of PV modules, thus decreasing the PV cell efficiency. PVT collectors make better use of the solar spectrum, supplying both electrical and thermal energy within the same area, while increasing the electrical efficiency. PVTs are especially interesting for applications where space is limited, combine the generation of electricity and heat in a single area, and can work most effectively with other energy sources such as heat pumps and coupled with thermal energy storage for provision when solar radiation is low. The average saved costs by PVT installation with available data is about 22 EUR/m2 annually. Investments of about 600 EUR/m2 are covered by saved fuel costs, considering the typical lifetime of a PVT system of at least 20 years, and reduce dependency on rising and fluctuating fossil fuel prices (depending on local feed in tariffs and prices for electricity, oil and gas, this value might vary a lot from case to case, See: Schubert, M. and Zenhäusern, D., 2020. Performance Assessment of Example PVT-Systems).

Energy use in pig farms can be assessed in the range 9.7-28.8 MJ/kg (Chen et al., 2015). Feed production is the largest energy consumer, with almost 72% of the total energy consumption whereas the remaining 28% is about direct on-farm energy use. Direct energy inputs are divided between transportation, heating, ventilation, watering, waste removal, lighting and other uses (such as mix and deliver feed, manure removal, mixing in slurry tanks, and power-washing). The key demand is due to the heating systems for the farrowing and first stage weaner houses and the mechanical ventilation systems. Therefore, pig barns show a significant potential of improvement of energy efficiency by means of a proper enhancement of the building envelope and the adoption of optimally controlled heating, cooling, and ventilation systems. Renewable energy sources and energy efficiency measures and technologies combined with energy conservation practices provide a unique opportunity for farms to reduce energy consumption and produce their own clean energy to become partially or even totally self-sufficient. More specifically, solar energy can be utilized in confined animal buildings, like poultry and pig farms, being able to put up for both electricity and heating needs. Heat pumps’ potential is focused on applications that allow their coupling with photovoltaic-thermal hybrid solar collectors or geothermal units. RES4LIVE aims to make the most of the significant de-fossilization potential of swine farms. Heat pumps will be demonstrated for both space and water heating applications. They will be also coupled with PVTs and geothermal heat storage, and smart control systems, which will monitor indoor environment and maximize the self-consumption.

The optimal thermal conditions for pigs are expressed as the thermo-neutral zone, which depends on the age of the pigs, but also on housing conditions, like air velocity, floor type, building insulation. Outside of this zone, cold or heat stress occurs, which results in discomfort, loss of productivity or even death.

Lactating and gestating sows and heavy fattening pigs are most at risk for heat stress. It results in changed lying behaviour, decreased feed intake and increased respiratory rate, skin and rectal temperatures. The most important consequences on productivity are a lower body weight of the offspring, higher abortion rate, feed conversion and mortality. As the internal heat production of pigs has increased the past 50 years due to increase in leanness, modern day pigs are more susceptible to heat stress. Combined with global warming, heat stress is occurring more frequently and severely throughout Europe, leading to serious economic losses.

Cold stress on the other hand is most critical for young pigs, since they don’t have brown fat tissue yet, which produces heat at low temperatures. It is an important cause of piglet mortality, but also of increased feed intake without increased body weight, and decreased meat quality.

It is very important to regularly check the actual ambient temperature in the pig pens and the pigs’ behaviour. Pay special attention to the new-borns, preventing cold stress, and to the sows and heavy fattening pigs, preventing heat stress. In RES4LIVE, the goal is to provide optimal comfort for the pigs with renewable energy systems and smart control. Heat pumps for example can provide both heating and cooling, which is vital for optimal productivity of the pigs.

The barn climate is a vital determinant of animal welfare and productivity. Ideally, the barn is climatized such that the heat produced during metabolism can be fully dissipated by the animal. When thermal balance is disturbed (by high ambient temperature or still air) certain physiological responses (panting, sweating) are triggered to adjust heat dissipation and/or production and restore the balance. Nevertheless, there is a limit to the efficacy of such responses, beyond which thermal stress occurs, leading to productivity loss and, in extreme cases, mortality. Dairy cattle are generally resistant to cold stress, but susceptible to heat stress, reportedly even at temperatures as low as 20°C. Heat stress is a significant challenge to sustainable dairy farming, especially in light of climate change and with continual genetic selection for higher productivity. Accurate criteria for when heat relief is needed remain the subject of ongoing scientific debate. In addition, while both practice and research have focused on the effects of temperature and humidity, there is growing awareness of the importance of air speed, with crucial implications for ventilation in dairy barns. In this context, RES4LIVE seeks to adapt and implement technologies that, while reducing reliance on fossil fuels, ensure effective prediction, prevention and mitigation of heat stress in dairy cattle as well. Data from pilot farms will be used to identify conditions of potential heat stress in various stages of growth and production. A smart control system will use these models for proactive control of the barn climate. The effectiveness of tube ventilation augmented with mechanical cooling of intake air in preventing and alleviating heat stress will be examined.

Agriculture 4.0 is the new approach towards farm management and precision agriculture. The ability to harness the technology advancements from other industries, such as IoT (Internet of Things), computer

science etc., allowed agricultural sector to evaluate and adopt them to achieve energy efficiency and optimal indoor conditions for the livestock. Agriculture 4.0 is combining low-cost sensors and actuators,

with cloud computing and artificial intelligence (AI) to achieve its goals and help farmers make better decisions, while at the same time reducing their environmental footprint.

Utilizing farmer-defined scenarios that consider specific livestock requirements, the areas occupancy and other characteristics, the IoT system is enabling smart control towards heating, cooling and ventilation

and optimize the microclimate, in terms of indoor air quality and thermal environment. To allow the smart control system to take the wheel and

operate automatically, the farms utilize smart sensors to

monitor the different environmental parameters,

such as temperature, relative humidity, wind speed and direction, hazardous gases (CO2, NH3, H2, O2, VOC), as well as energy consumption data. Moreover, the system can collect baseline data2 to evaluate, assess and compare “Before” and “After” conditions.

Precise indoor environmental and energy smart control are integral parts of the RES4LIVE implementation. The data will be available to the users in real-time, through a cloud platform, which will:

• allow remote monitoring;

• provide useful analytics, and;

• perform actual control of the connected devices.

The above-mentioned features will assist in both everyday operations and long-term farm management.

For homeothermic animals, thermoneutral zone is the range of ambient temperature in which normal metabolism provides enough heat to maintain an essentially constant body temperature. For laying hens this is between 10°C-25°C and is prerequisite for attaining maximum productivity. Raising hens outside these limits, initiates physiological responses that negatively affect performance and egg quality. Prolonged periods of heat stress are accompanied by reduced feed intake, reducing growth rate of pullets, and egg production and size for hens. Since birds cannot sweat, hens are panting at high temperatures to reduce their core temperature through mouth and the respiratory system. However, this physiological adaptation results in eggs with reduced eggshell strength and thickness and increased percentage of cracked or broken eggs. When hens are cold stressed, their feed intake increases in order to produce more metabolic heat and compensate with the heat losses from their body. This has unfavorable effects on feed utilization for growth, in case of pullets, and for egg production in case of laying hens, leading to increased costs. Moreover, during prolonged periods of cold stress, especially during night hours, small chickens are piling on top of each other, and a high incidence of mortality is usually observed because of suffocation. The negative effects of extreme temperatures are often combined with inadequate relative humidity and air velocity values. Therefore, in the framework of RES4LIVE, we deem of major importance the use of equipment that can accurately adjust microclimate conditions - heat pumps and smart control systems - in a laying hens house in order to attain maximum productivity with respect to animal welfare and egg quality.

Livestock buildings facilities need precise control of air temperature and relative humidity. In these demanding environments, the heat pump (HP) is the only indoor climate control technology that can ensure such conditions, since it is designed to provide heating, cooling, and dehumidifying in a space, by transferring thermal energy form a cooler space (source) to warmer space (sink) using electricity.

They can draw energy from ambient air or water (coming from ground or solar collectors) to heat internal air (typical A/C heating mode) or provide hot water (35-50 oC). In cooling mode energy is extracted from hot spaces by circulating cold water or air with a piping system, in order to lower the comfort temperature of the animals (15-25 oC).

The efficiency of a heat pump is expressed in the COP value (Coefficient of Performance), which indicates how much electrical energy is needed to generate thermal energy.

Even though the heat pumps are powered by electricity (which may or may not have a renewable source), because of their high efficiency are considered a Renewable Energy Source (RES) technology, presenting no onsite emissions. A properly dimensioned heat pump (for a well-insulated space, about 0.09 kW/m2) can lead to cost savings up to 50-60% and a significantly lower environmental impact compared to a gas-fired installation for heating, and reduced CO2-eq. emissions. Their manufacturing specific cost can be of the order of 300-600 €/kWth, while they need limited maintenance.

Their capability of operating in heating, cooling, and dehumidifying mode, can provide superior thermal comfort of the hosted animals, leading to increased productivity with minimum climate change impact.