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, C6H12O6.
With food intake,
-- When it is in the blood
stream, glucose is called… blood sugar increases;
with physical (or mental)
“blood sugar.”
activity, it decreases.
Insulin is the hormone that moves glucose
from the blood stream into the cells.
-- Our bodies produce glucose out
of the foods that we consume.
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,
(NH2)2CO after
digestion
O
H–N–C–N–H
H
H
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.
coal gasification: coal is treated
with superheated steam
to make the gases
CH4, H2, and CO
coal gasification plant
-- 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.
Nuclear energy, from the splitting or fusing of atoms,
also is nonrenewable. FISSION
-- a lot of bang for
your buck, but
there is the
problem of
U or Pu
daughter
released
hazardous waste disposal
nuclei
cooling towers
neutrons
containment building
Renewable energy sources include:
solar
solar panels
wind
wind generators
geothermal
geothermal plant in Iceland
hydroelectric
biomass
crops, biowaste
biomass plant in Britain
Solar heating can be used to generate
CO and H2 gases, which could be burned...
for energy or reacted together to get the heat back.
heat
from + CH4 + H2O
Sun
CO + H2
Solar (or photovoltaic) cells
directly convert solar
energy into electricity.
Problems with solar energy:
-- it is dilute
-- storing it for later use
-- it fluctuates w/time of day and weather conditions