Methane from Biomass

1
Methane from Biomass

• Methane makes up 85 of the natural gas extracted
  from the ground.
• In the presence of water and absence of oxygen,
  organic material will ferment naturally.
• Such organic materials include
• Crops
• Agricultural waste (animal or vegetable)
• Waste from lumber mills
• waste from breweries
• Algae
• Sludge from sewage treatment plants
• Municipal waste
• Fermentation by bacteria in the absence of oxygen
  is called anaerobic fermentation

2
Methane from Biomass

• Same heating value as natural gas
• High conversion efficiency(50-70 of the useful
  energy is converted)
• High cost
• Useful in systems that can generate their own
  power - for example sewage plants

3
Biodiesel

• Diesel fuel made from vegetable oil, recycled
  cooking grease or oil and animal fat
• Used as a fuel additive, designate the same way
  we designate ethanol fuels-i.e B where is the
  amount of biodiesel in the diesel fuel.
• B20 widely used in trucks and school buses

4
Nuclear Energy

• Nuclear Fission - the splitting of two atoms
• Nuclear fusion the combining of 2 atoms
• Both process release energy

5
Atomic structure

• Atoms are composed of protons , neutrons and
  electrons discovered in the 1930s
• Protons positively charged
• q1.60217648710-19 C
• m1.67262158 10-27 kg
• Neutrons no charge
• m1.6749 x 10-27 kg
• Electron negative charge
• q -1.60217648710-19 C
• m 9.1093821510-31 kg

6
Atomic structure

• Protons and neutrons make up the nucleus
• Electrons orbit the nucleus at specific distances
  known as energy levels
• Atomic number number of protonsZ
• Atomic mass number A Z N, where N is the
  number of neutrons
• Atomic mass total mass the electrons, protons
  and neutrons
• Atomic weight the ratio of the average mass of
  an atoms 1/12 of the mass of an atom of
  carbon-12.
• Ion if an atom loses or gains an electron and
  has a net charge
• Isotope-atom has the same number of protons but
  different number of neutrons

7
Atomic Structure

• Atoms are held together by forces
• There are four forces in nature
• Gravity -force between masses
• Electrostatic forces-like charges repel unlike
  charges attract
• Strong nuclear force - causes an attraction
  between protons and neutrons
• Weak nuclear force causes protons to transform
  into neutrons and neutrons in to protons

8
Atomic Structure

• In atoms, the electrostatic force is holding the
  electrons to the nucleus, since the electrons are
  negatively charged and the protons are positively
  charged.
• The protons in the nucleus are being pushed apart
  by the electrostatic force since they have the
  same charge, but the strong nuclear force
  overcomes this repulsion on the atomic size
  scales and holds the protons together.

9
Fission

• In the late 1930s, it was discovered that if a
  uranium nucleus was bombarded by neutrons, it
  absorbed the neutron and became an unstable
  isotope of uranium, which then spilt into 2
  separate atoms (Krypton and Barium) and emitted
  more neutrons and gamma rays

10
Is mass conserved?

• Now the mass of the fission products plus the
  excess neutron should equal the mass of the
  initial incident neutron and the uranium. But it
  doesnt.
• Where did the mass go?
• Well, remember E mc2 - mass cannot be created
  or destroyed, only converted to and from energy,
  so the missing mass must be converted into energy.

11
How much energy

• 200 MeV is released per fission event
• The fission of 1 g of uranium or plutonium per
  day liberates about 1 MW.
• This is the energy equivalent of 3 tons of coal
  or about 600 gallons of fuel oil per day
• No CO2 emissions!
• Vastly superior in terms of energy per amount of
  fuel

12
Self sustaining or chain reaction

• The fission reaction itself releases neutrons,
  these can be used to fission additional nuclei,
  so the elements are there for a sustained or
  chain reaction.
• Tremendous power capability made this an ideal
  weapon.