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