Quiz: What You Don't Know About Food, Water, and Energy


Photograph by Francisco Negroni

You know that food gives you energy, and water is essential for life. But did you know how much energy and water go into the food you eat?

The food sector accounts for what percentage of the world's total energy consumption?

  • 5 percent
  • 15 percent
  • 30 percent
  • 40 percent

The food sector accounts for 30 percent of all global energy consumption and 22 percent of total greenhouse gas emissions, according to the United Nations' Food and Agriculture Organization (FAO).

Thanks to the "Green Revolution" in agriculture, the world's grain harvest increased 260 percent between 1950 and 1984. Which of the following was NOT a factor driving up production?

  • Increased grain land per capita
  • Increased irrigation
  • Increased fertilizer
  • Breeding of seed varieties with tolerance for high levels of fertilizer

Grain land per capita fell 30 percent over that time period. The unprecedented food production boost resulted from increased use of fossil energy both for irrigation and synthetic nitrogen fertilizer (in conjunction with selective plant breeding to raise nitrogen tolerance.)

About two-thirds of global water supplies used for irrigation are drawn from underground aquifers. How much of that water is obtained through energy-intensive pumping?

  • 26 percent
  • 36 percent
  • 66 percent
  • 86 percent

About two-thirds of the total aquifer water for irrigation is extracted through energy-intensive pumping from deep wells. That share is projected to rise to 87 percent by 2050, as shallower water reserves become depleted. Current extraction rates exceed the rate of recharge.

For every calorie of beef consumed, how many calories of fossil fuel energy are used in the food supply chain?

  • 10
  • 20
  • 30
  • 40

Beef production, relying on large amounts of feed grain, is energy-intensive, with 40-to-1 fuel-to-food value in calories. On average, every calorie of food we consume uses up five calories of fossil fuel energy for pumping water, fertilizing, harvesting, processing, transportation, and distribution.

What country devotes 65 percent of its domestic oil use to providing fresh water?

  • Chile
  • Saudi Arabia
  • Australia
  • Kenya

Saudi Arabia uses 65 percent of its oil for desalination of water and the associated electricity generation.

Which process in the global food-supply chain results in the largest greenhouse gas emissions, according to the United Nations' Food and Agriculture Organization?

  • Crop production
  • Livestock production
  • Processing and distribution
  • Retail, preparation and cooking

Because methane has 25 times the global warming potential of carbon dioxide, the digestive methane emissions from ruminants like cattle help to make livestock production more greenhouse-gas intensive than either crop production or other stages of the food-supply chain.

How much can the average household in the United States reduce its greenhouse gas emissions by "buying local," for example, at farmers' markets instead of supermarkets?

  • 5 percent
  • 15 percent
  • 25 percent
  • 35 percent

The average U.S. household could expect to save just 4 to 5 percent of its greenhouse gas emissions by buying local, researchers at Pittsburgh's Carnegie Mellon University calculated. Long-distance transport of food by ship or rail can be done at low energy per ton, and growing food in high-productivity locations saves energy.

Which one of the following forms of renewable energy, on average, requires the most water per unit of energy produced?

  • Wind energy
  • Solar thermal energy
  • Biomass energy
  • Hydropower

Due to irrigation needs, the global average requirement for biomass energy is 70 cubic meters (18,492 gallons) of water per gigajoule of energy, compared to just 22 cm (5,811 gallons) for hydropower, 0.27 cm (71 gallons) for solar thermal, and no water for wind energy production, according to the Water Footprint Network, a Dutch nonprofit.

Which of the following is FALSE about solar-powered pumping systems for irrigation?

  • They have a higher initial cost than conventional petroleum-powered pumps.
  • They have more moving parts and require more maintenance than petroleum-powered pumps.
  • They have lower long-term costs than petroleum-powered pumps, because fuel is free.
  • They have been shown to improve rural farm productivity and living standards in projects throughout the world.

Solar photovoltaic (PV) pumping systems are more reliable than diesel or gasoline pumps because they have fewer moving parts and require only unskilled labor to clean solar panels. Studies dating back to the 1990s have shown that lifetime costs of solar irrigation systems are lower.

In Europe and North America, about how much food is thrown away or wasted per person each year?

  • 10 pounds (4.5 kilograms)
  • 50 pounds (22.7 kg)
  • 100 pounds (45.4 kg)
  • 200 pounds (90.1 kg)

In wealthy countries, about 210-250 pounds (95 to 115 kg) of food per capita is wasted annually, as fresh produce rots in the fridge, food is tossed after expiration dates, or left on the plate unconsumed. As a result, about 38 percent of global energy spent on food is wasted, says the United Nations' FAO.





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