Comparison of Energy Efficiency & Water Footprints in Food Production
- The systems approach looks at all components, relationships and feedback effects within a process
- The approach is useful for showing whether the impacts in one area of the system have consequences on another
- Food production is a system:
- Inputs - things that enter the system
- Human inputs like labour, money, and technology
- Physical inputs like land, soil, seeds and water
- Transfers/processes/stores - the operations that occur during food production, turning inputs into outputs
- Weeding, ploughing, sowing, milking, rearing, shearing etc.
- Decision-making by states and farmers
- Changes and patterns in land use
- Outputs - the products (the end of the system)
- Positive outputs - crops, milk, eggs, animal fodder, profits/wealth
- Negative outputs - waste, air/water/land pollution, soil erosion
- Inputs - things that enter the system
- The system may also have feedback effects:
- Positive feedback - imbalanced equilibrium with stagnation, decline or complete loss of the system
- Natural disasters may also impact positive feedback
- Negative feedback - return to equilibrium with increased reinvestment and innovation
The systems approach to food production
- Food systems can be intensive or extensive
- Intensive systems:
- Capital intensive - high capital and low labour inputs
- Labour intensive - low capital and high labour inputs
- Profit oriented
- The land is relatively small
- Output is high
- Extensive systems:
- Small labour and capital inputs
- Rely on natural characteristics e.g. rainfall and soil quality
- The land is larger
- Fewer agricultural technologies
- Output is low
- Subsistence oriented
- Intensive systems:
Advantages of the systems approach
- The systems approach can compare energy efficiency and the water footprint within food production systems
- There are many different types of farms/food production systems
- Each food production system will have different energy efficiency and water footprints
Types of food production systems
Type of farming | Characteristics |
Arable | Crop growth, like barley or wheat |
Pastoral | Rearing animals/livestock e.g. ranching |
Mixed | Growing crops and rearing animals simultaneously |
Commercial | Profit-oriented - produce is sold on markets e.g. coffee or cotton |
Subsistence | Growing crops/rearing livestock purely for the farmer and family |
Sedentary | Use of the same land each year e.g. maize or sugarcane |
Nomadic | Herding of livestock to find new grazing pastures (moving from one place to another) |
Energy efficiency
- Modern food systems require man-made technologies and resources to function
- These may need large energy inputs to operate
- The Energy Efficiency Ratio measures the energy efficiency of a system
- It is calculated by:
- Total outputs ÷ total inputs
- Inputs can be:
- Direct e.g. fuel, labour, machinery, planting
- Indirect e.g. irrigation, electricity, fertilisers and pesticides
Energy inputs and outputs in a food production system
- Energy efficiency can be affected by:
- Climate
- Warmer climates are more efficient. Crops will need fewer energy resources (they can use the sun)
- Wetter climates are more efficient as they need less irrigation
- Soil type
- Some soils are not fertile and require more fertilisers
- Crop type
- Certain crop types need more energy
- Topography
- Flatter topographies use less energy as there is lower water/nutrient runoff
- Farming type
- Certain farming types may be less energy-efficient than others
- Use of technology
- Greenhouses use more energy than cultivating open land
- Climate
- The energy efficiency ratio is useful for showing the efficiency of different food production systems
- However, it ignores energy use in other areas of production e.g. packaging, processing, distribution and consumer preparation before consumption
Water footprint
- All food systems require embedded water to operate
- Agriculture uses roughly 85% of global water consumption
- The water footprint can be calculated by summing up all the water used in the system
- It includes the consumption and pollution of freshwater (inputs and outputs)
- Water is separated into 3 categories:
- Green - water from rainfall that is evaporated, transpired or stored in the soil or used by crops
- Blue - water from surface/groundwater sources that evaporates, is used for a product or is returned to another source e.g. for irrigation
- Grey - sources of water pollution into freshwater through pipes or from indirect leaching/runoff
- Factors affecting the water footprint include:
- Climate
- Wetter climates require less irrigation
- Topography
- Fewer pollutants from runoff on flatter land
- Type of food production system
- Meat production requires more water than vegetable growth
- Pastoral farming has a higher water footprint than arable farming
- Certain crops may need more fertiliser or pesticides (this may cause more pollution)
- Climate
- The water footprint is useful for showing the sustainability of different food production methods
- It can be used to assess and produce more sustainable methods of water use
Litres of water needed to produce food products