The relation between energy costs and food production
Summary
- Food takes energy to produce
- Some modern food production is exceedingly energy intensive
Details
- factors that determine energy costs of food: fertilization and pesticide, irrigation, method of harvesting, processing, packaging, transport, retail, trip to buy food and cooking.
References
Quotes
The energy costs of common foodstuffs range widely, due to different modes of production (such as intensity of fertilization and pesticide applications, use of rain-fed or irrigated cropping, or manual or mechanized harvesting) and the intensities of subsequent processing. The typical costs of harvested staples are around 0.1 toe/t for wheat, corn and temperate fruit, and at least 0.25 toe/t for rice. Produce grown in large greenhouses is most energy intensive; peppers and tomatoes cost as much as 1 kgoe/kg. Modern fishing has a similarly high fuel cost per kilogram of catch. These rates can be translated into interesting output/input ratios: harvested wheat contains nearly four times as much energy as it was used to produce it but the energy consumed in growing greenhouse tomatoes can be up to fifty times higher than their energy content. These ratios show the degree to which modern agriculture has
become dependent on external energy subsidies: as Howard Odum put it in 1971, we now eat potatoes partly made of oil. But they cannot simplistically be interpreted as indicators of energy efficiency: we do not eat tomatoes for their energy but for their taste, and vitamin C and lycopene content, and we cannot (unlike some bacteria) eat diesel fuel. Moreover, in all affluent countries, food’s total energy cost is dominated by processing, packaging, long-distance transport (often with cooling or refrigeration), retail, shopping trips, refrigeration, cooking, and washing of dishes: at least doubling, and in many cases tripling or quadrupling, the energy costs of agricultural production.