General Science 101

General Science 101Chapter 1 - Energy and Power and the Physics of ExplosionsChapter 1: Energy and Power and the Physics of ExplosionsWhat is energy?

Energy can be defined as the ability to do work.

Energy must be conserved and cannot be created nor destroyed.

This means that energy can transform into other forms (heat, chemical, mechanical, biological, etc.)

To put it simply, energy makes the Earth go around and what allows us to exist!EnergyTypes of EnergyKineticPotentialChemicalNuclearHeatGravitationalSince energy is conserved, it must transform from one type to another.

Kinetic energy energy of motion

KE = m v2

Potential energy stored energy

PE = m g hEnergyConservation of Energy Kinetic energyKE = m v2

Potential energyPE = m g h m v12 + m g h1 = m v22 + m g h2 m v12 + m g (0) = m (0)2 + m g h2

m v12 = m g h2 v12 = 2 g h2 PowerPower is the rate at which energy is used (energy over time).

Power is measured in Joules per second (J/s) or Watt (W)How to measure energy!We measure energy using different units.

In Chemistry and Biology, people use the calorie (cal) or kilocalorie (Cal). 1 Cal = 1000 cal.1 Cal is equal to a food calorieThis is amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

In Industries, people use the kilowatt-hour (kWh)1kWh ~ 1000 Cal

In Physics, people use the joule (J)1kWh = 3.6 million JOne can of soda contains150 Cal = 150,000 cal = 0.150 kWhor630,000 J

Not an endorsement of Coke products!How to measure energy!The average household uses 12,000 kWh of energy each year.

That is equivalent to:~80,000 cans of soda (~150 Cal each)~120,000 bananas (~100 Cal each)~2,000,000 grams of coal~360 gallons of Gasoline

The United States uses ~4,000,000,000,000 kWh per yearWe have to generate it somehow.16 W bulb (on 10 hours) 4.8 kWh/month (57.6 kWh/year)100 W bulb (on 10 hours) 30 kWh/month (360 kWh/year)Refrigerator 36.7 kWh/month (440 kWh/year)Dishwasher 41 kWh/month (492 kWh/year)Clothes Washer 24.9 kWh/month (299 kWh/year)Electric Clothes Dryer 74.7 kWh/month (896 kWh/year)Stove & Oven (self-cleaning) 61.25 kWh/month (735 kWh/year)Energy DensityHow energy sources compare!What is interesting about this?

Understanding Energy: TNT vs. CCCsChemical Reactions and energy transfer are key!

Requires digestion, which is a slow process, the chemical energy than has to convert into heat and other materials.Transfers chemical energy to heat quickly. This quickness produces gases that explode.

Understanding Energy: BatteriesWhile batteries contain 340 times less energy than their weight in gasoline, they provide a unique opportunity for portable devices.

Electrical energy storage Requires massive storage units, which lowers the energy density

Understanding Energy: GasolineSimilar to TNT, Gasoline converts chemical energy to explosive energy and heat. However, gasoline needs air to do this.

While electric cars run off of batteries, those batteries must charge and that power has to come from somewhere.

This is typically a coal or natural power plant.

Therefore, electric cars are not zero emission vehicles unless you charge them with a zero emission source (nuclear, solar, wind, etc.)

The breakdown:Electric CarGasolineEmissions 0.23 lbs./MJ (Coal)0.16 lbs./MJ

Cost per Mile$0.01$0.04

This ignores manufacturing costs and price of vehicle or emissions due to energy production.

Electric vs. GasolineCars EditionChevy CruzTelsa Model SUnderstanding Energy: Hydrogen FuelLiquid Hydrogen gas has ~3 times more chemical energy per gram than gasoline.

Sounds goodbut!

It is ~3 times less energy per gallon.1 kilogram of hydrogen ~ 1 gallon of gasoline

Compressed hydrogen gas has 6 times less.

Combines hydrogen and oxygen to produce energy and water

Hyundai Blue

Hydrogen cannot be found.

It has to be made!

Electrolysis makes hydrogen and oxygen from water. Due to density13Understanding Energy: UraniumUranium has a huge energy density (30 million times that of TNT)Fission reactions break apart uranium to produce energy and lighter radioactive elements

Uranium takes advantage of chains reactions to break atoms and produce large amounts of energy. This is a achieved through the critical mass.Due to density14Harnessing Energy The Steam Engine

Since the 1800s, Steam has been the easiest manner to transfer energy.

- Boats- Trains- Power Plants

It is just matter of how you heat the water.

Understanding Energy: Coal/Natural GasBoth generate a considerable amount of CO2, but they produce the most energy for the United States.Similar to a nuclear power plant, coal and natural gas plants burn their fuel to boil water and turn a turbine.Uranium takes advantage of chains reactions to break atoms and produce large amounts of energy. This is a achieved through the critical mass.

Due to density16Understanding Energy: Nuclear PowerNuclear power has minimal waste, but that waste is radioactive for 1000s of years.Takes advantage of the energy produced by the fission of Uranium in a controlled environment.Generation IV Reactors could revolutionize the nuclear power industry by using a lead convection cooled system.

Due to density17Understanding Energy: GeothermalPumps water deep into the ground where it is heated by the earth. Steam then travels up and pushes a turbine.

Due to density18Understanding Energy: Solar Power (Concentrated)Collects sunlight and boils water to generate electricity through a turbine.

These types of solar collector plants are very efficient, but require large amounts of area.Due to density19Understanding Energy: Solar Power (Panels)Solar panels use advanced materials to convert sunlight into an electric current 150 (cheap) 400 (expensive) W/m2~3000 sun hours per year (varies by place)

0.4 kW * 3000h = 1200 kWh/year for one panel

Therefore, the average household needs approximately 10 panels to get 12,000 kWh per year. Assuming you buy the expensive ones!

Due to density20Understanding Energy: HydroelectricUses river water to push a turbine and generate electricity.

Possible environmental concerns:

Impact of a reservoirDisplacement of animals and other organisms

Advantages:

Controls water flow Fairly consistent energy supplyDue to density21Understanding Energy: Wind/Tidal PowerGenerates power by having a turbine turned by wind or the tidal forces.

Due to density22Cost of EnergyNuclear power is the cheapest, but public apprehension continues to hold the building of newer plants.

Coal is still the work horse for the United States, China, and India, which means the CO2 emissions are not stopping anytime soon.

Solar has wonderful possibilities, but needs to become more cost effective and efficient.

The amount of energy used by each state divided by its population.

Essentially, how much each person (on average) uses in that state.

Millions of BTU per capitaEnergy Information Administration (EIA)How much energy does the US consume?How much energy does the US consume?

Energy Information Administration (EIA)CO2 EmissionsNuclear power is the cheapest, but public apprehension continues to hold the building of newer plants.

Coal is still the work horse for the United States, China, and India, which means the CO2 emissions are not stopping anytime soon.

Solar has wonderful possibilities, but needs to become more cost effective and efficient.

This will be covered more extensively when we look at Climate ChangeEnergy Take AwaysEnergy is defined as the ability to do work, which means it is critical for life.There are many ways to generate energy (Chemical, Mechanical, Solar, Atomic) .Most energy source include boiling watera slight modification of a steam engine.Some sources are better than others, but the ability to store energy is one of our biggest challenges.