Energy is the most important resource for progress and growth of any agriculture.  Pakistan being agro-based country is facing energy and water scarcity problems despite other problems of low productivity and soil conservation.  Increased food production to meet rising demand of increasing population will also be a great challenge for agriculture. Energy and water scarcity are two major obstacles to sustainable agriculture and food security. Sustainable agriculture is related to agriculture production system without damaging the environment and future generations and food security is access by all people at all time for active and healthy living at present plus ability to provide in future. Fossil fuel based energy generation is the current practice in agriculture in Pakistan and fossil fuel based energy is expensive and causes  GHS emissions enhancing climate change process.  To mitigate climate change and reduce GHG emissions, there is a need to shift current fossil fuel based energy generation to Renewable based energy generation. Non-fossil fuel based renewable energy sources include Solar, Wind, Biomass, Hydroelectric and Geothermal . Energy and water scarcity problems can be solved by the use of sustainable, clean and Renewable energy sources which will ultimately become instrumental in elimination of environmental damages and climate change.

Introduction

Food security and sustainable agriculture are the two main objectives of agriculture production process and these objectives can only be achieved by changing the farming practices from fossil based energy generation to Renewable Energy based farming. We will discuss that what types of renewable technologies available and how we can use them in our agriculture production system, what are the challenges and what strategies should be adopted to solve water and energy scarcity issues.

 Solar Photovoltaic

Technology that converts solar light radiations into electrical energy is called Solar Photovoltaics (Solar PV). The electricity generated from Solar PV can be used for running farm machinery, lighting, water pumping in agriculture production process. The solar electricity generation can be in the form of off-grid, hybrid and on-grid. In off-grid, the only source of power is solar which charges the batteries and then stored DC energy can be converted into AC electricity which can be used for lighting, running the farm machinery, running air-conditioners and water pumps. One weakness of this off-grid system is that when solar charged battery is discharged, system stops functioning and also battery needs to be replaced after three or four years. The major components used in this system are solar PV modules, solar charge controllers, solar inverter, solar mounting and DC cables. Such solar systems vary from 500W to 20 KW. Second type of solar power generation is hybrid solar system whose battery is only charged from solar but when there is no solar, the battery is charged from Grid or wind power or any other alternate AC source. Such systems are good where Grid or alternate source of electricity is available. One other application of this system is Micro-grid which is independent system supplying electricity to one farming community. Third is on-grid solar system which has no battery but it is sync with the Grid and when there is no Grid or load shedding the system does not produce energy and there is need to run generator to provide AC electricity to inverter of this system, This system is very useful where the Grid is available and load shedding is very less. Also the group of farmers can get installed this system along with Diesel Generator and they can do combined investment and run the system. In net metering based solar systems, the extra solar energy from its use is exported to Grid and meter revers its direction. Net metering SRO 892 (2015) has been promulgated and now every three phase user can install solar system with net meter and can export and import energy from Grid. In case of export the meter will move in reverse direction and units will be credited to user account. Solar based water pumping is very common in the world and water scarcity problem can be solved by installation of solar water pumps. Solar pumping not only produces water but saves energy also. The payback is about three years and pump has life of 15 years. Solar can be used for underground water heating, solar green houses and poultry farms. Hot water can be used for underground heating, cleaning of utensils and bathing applications. Solar prices have gone down substantially that the price of solar based power generation is equal to fossil based power generation.

 Solar Thermal

Technology that coverts solar heat radiations into heat energy is called Solar thermal.  The collectors used are low temperature tube and flat type and high temperature concentrated collectors. Collectors are of two types i.e passive and active. Low temperature collectors heat water upto 90 degree and high temperature concentrated collectors produce steam up to 800 Degree centigrade. The solar thermal technology based systems can be used for water heating, food drying, cooking, space heating, solar greenhouse and under-ground soil heating.

 Wind Power

Wind Power potential most exists in Sind and Baluchistan provinces. Wherever wind at the rate of 7 to 9 meter/second exists, wind power can be used to generate electricity by wind turbines which can be used for running farm machinery, pumps, air-conditioners and Poultry equipment. Wind Power system are small, medium and large. Small and medium systems up to 200KW can be installed at farms where wind speed is available. From wind turbine, directly wind pumps can be run by revolution of turbine blades.

 Mini and Micro-Hyrdo Power (MHP)

Hydro energy can come from the natural flow of water.  Amount of energy depends upon the flow and head of the water. At canals or run of river small heads micro and mini Hydro (MHPs) Turbines cab fixed varying from 5KW to 500KW and such MHP systems generate electricity which can be used for running farm machinery and water pumps. The MHP system consists of intake, canal, Forebay, Penstock, Turbine, generator and control system.

 Bio-Energy

Bio-energy  is renewable energy made available from materials derived from biological sources. Biomass (wood, corn, cotton sticks, sugarcane, bagasse, soybeans, flowers, agriculture, livestock and municipal waste etc) can be converted into bio-energy from different processes ( direct combustion, thermo-chemical process, bio-chemical process, pyrolysis, anaerobic fermentation, landfills,  ethanol fermentation, bio-diesel etc). Bio-energy can be in the form of fuel ( bio-gas, bio-ethanol, Bio-diesel) which can be used for running farm machinery, tractors, pumps, cooking  in agro-food chain,

 Conclusion

Use of Renewable energy sources in agriculture production process not only will solve problems of energy and water scarcity but will ensure food security and enhance sustainable agriculture in Pakistan. The shift toward increase of renewable energy will reduce dependence on fossil fuel and will reduce import bill and provide greater saving to the country. This will also enable us to meet the objective of UN Millennium Development Goad 07. The use of Renewable energy sources will improve soil quality and reduce the need for fertilizer, pesticides and herbicide application.