Food and Fuel fuel value: the energy released when 1 g of a material is combusted -- measured by calorimetry calor is the Latin word for “heat” metria is the Greek word for “to measure”

Food The body runs on glucose, C 6 H 12 O When it is in the blood stream, glucose is called… “blood sugar.” -- Our bodies produce glucose out of the foods that we consume. With food intake, blood sugar increases; with physical (or mental) activity, it decreases. Insulin is the hormone that moves glucose from the blood stream into the cells. Diabetics must closely monitor blood sugar levels and take insulin to keep that level within range.

carbs: 4 kcal/g; quickly broken down into glucose; not much can be stored as carbs fats:9 kcal/g; broken down slowly; insoluble in water; easily stored for future use proteins: 4 kcal/g; contain nitrogen which ends up as urea, (NH 2 ) 2 CO after digestion H–N–C–N–H HH O

Fuel fossil fuels: coal, petroleum, natural gas -- products of what used to be living things -- nonrenewable coal-burning power plant Future oil supplies are in question.

-- most impurities (e.g., sulfur compounds) are easily removed in this process -- the fuel gases can be transported by pipeline and then burned for fuel Combustion of ANY fuel contributes to the greenhouse effect. coal gasification: coal is treated with superheated steam to make the gases CH 4, H 2, and CO coal gasification plant

Nuclear energy, from the splitting or fusing of atoms, also is nonrenewable. -- a lot of bang for your buck, but there is the problem of hazardous waste disposal FISSION daughter nuclei released neutrons cooling towerscontainment building U or Pu

Renewable energy sources include: solar wind solar panels wind generators

geothermal hydroelectric biomass geothermal plant in Iceland biomass plant in Britain crops, biowaste

for energy or reacted together to get the heat back. Solar heating can be used to generate CO and H 2 gases, which could be burned... from + CH 4 + H 2 OCO + H 2 heat Sun Solar (or photovoltaic) cells directly convert solar energy into electricity. Problems with solar energy: -- it is dilute -- it fluctuates w /time of day and weather conditions -- storing it for later use