food and fuel fuel value: the energy released when 1 g of a material is combusted -- measured by...
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Food and Fuel
fuel value: the energy released when 1 g of a material is combusted
-- measured by calorimetry
calor is the Latinword for “heat”
metria is the Greekword for “to measure”
Food
The body runs onglucose, C6H12O6.
-- 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 glucosefrom the blood stream into the cells.
Diabetics must closely monitorblood sugar levels and take insulinto 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 downslowly; insoluble inwater; easily storedfor future use
proteins: 4 kcal/g; contain nitrogen which ends up as urea, (NH2)2CO after
digestion
H–N–C–N–H
H H
O
Fuel
fossil fuels: coal, petroleum, natural gas
-- products of what used to be living things -- nonrenewable
coal-burning power plant
Future oil suppliesare 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 fuelcontributes to the greenhouse effect.
coal gasification: coal is treatedwith superheated steamto make the gasesCH4, H2, 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
daughternuclei
releasedneutrons
cooling towers containment 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 generateCO and H2 gases, which could be burned...
from + CH4 + H2O CO + H2
heat
Sun
Solar (or photovoltaic) cellsdirectly convert solarenergy into electricity.
Problems with solar energy:
-- it is dilute
-- it fluctuates w/time of day and weather conditions
-- storing it for later use
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