Sustainable Food Guide
|Environmental Practice at Work © 2005|
|Energy Issues... |
Food is energy. And it takes energy to get food. Food must yield more energy to the eater than is needed in order to acquire the food. If this energy balance remains negative for too long, death results.
The energy ratio between food energy (out) and energy in has decreased dramatically in last 50 years. It was about 100 for traditional pre-industrial societies to less than 1, as fossil fuel use has increased.
Fruit and vegetable cultivation in the UK has an output/ input ratio is between 2 and 0.1 (0.002 for winter greenhouse vegetables) where 1 calorie of food energy ten calories of energy input. Beef production ratio is between 0.1 and 0.03.
The food system has become almost completely dependent on crude. Virtually all of the processes in the modern food system are dependent upon this finite resource. See Eating Oil
The ‘Green Revolution’ requires fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon power irrigation. The Green Revolution increased the energy flow to agriculture by an average of 50 times the energy input of traditional agriculture. Between 1945 and 1994, energy input to agriculture increased 4-fold while crop yields only increased 3-fold. In the US, 400 gallons of oil equivalents are expended annually to feed each American (1994). Since then, energy input has continued to increase without a corresponding increase in crop yield. We have reached the point of marginal returns.
These ratios refer to the energy consumed up to the farm gate and exclude processing, packaging and distribution. UK imports of food products and animal feed involved transportation by sea, air and road amounting to over 83 billion tonne-kilometres, requires 1.6 billion litres of fuel. Energy use is the ‘flip side’ of climate change and also includes the miles to transport food.