Energy: a Prerequisite for Life

1. Energy: a Prerequisite for Life

2. -15 10 m EM radiation gamma rays X-rays Ultra-violet Visible Infrared Microwave Radio waves • Many wavelengths of light outside of visible • Astronomers must consider the full EM spectrum 1000 km

3. What does the Emitted Wavelength of EM Radiation Depend on? Temperature of the emitting object

4. So What Makes Life on Earth Possible? The Sun Emits Visible EM Energy Which Provides Global Climate On Earth That Is Conducive To The Formation And Sustenance Of Life As We Know It

5. Stars are massive gaseous body in outer space that generate energy through nuclear fusion and therefore emit visible light; petawatt (1015 watts) Solar energy comes from the rearrangement of protons and neutrons  this energy powers the stars

6. petawatt (1015 watts)

7. petawatt (1015 watts)

8. Energy input = Earth’s output 1) Ein (from the Sun) • Eout • 2) Reflectivity (Albedo) • Earth’s surface & • Atmosphere • (Greenhouse gases)

9. Brightness (Ein) depends on the distance of emitting object: Inverse Square Law: Ein = Measuring ‘b’ and knowing ‘L’ yields ‘d’ Of b, L, d -- which are directly measurable for astronomical sources?

10. New Core Curriculum: Foundations of Scientific Process EM radiation is not the only form of energy that exists and that is important for modern life! What other forms of energy exist besides EM radiation ? What is Energy? Energy is defined as the ability to do work and produce/transfer heat

11. ENERGY = WORK + HEAT Don’t Confuse Power, Work & Energy… Energy: In colloquial language, ENERGY is equated with vigor, liveliness and vitality In science, ENERGY is defined as the ability to do work and transfer heat

12. WORK Don’t Confuse Power, Work & Energy… • not concerned with a nature of the task, tiredness, etc. • defined as force acting through certain distance units: Joules, calories (cal), nutritional Calorie (kcal)

13. HEAT Don’t Confuse Power, Work & Energy… • energy of atomic / molecular motion • this energy always flows • from warmer to cooler object units: Joules, calories (cal), nutritional Calorie (kcal)

14. POWER Don’t Confuse Power, Work & Energy… • work being done in a certain time frame P = W / t units: [J/s = Watts, horse power: 1 hp = 746 W]

15. Energy Can Be Classified As Kinetic (KE) or Potential (PE) Energy Etotal = KE + PE PE can be converted to KE and KE can be converted to PE

16. Most technological devices are energy-form converters

17. out there, here’s the skinny Energy is never created or destroyed Law of Conservation of Energy Energy is never created or destroyed, it just converts from one form to another, the total energy always remains constant Every time work is being accomplished or heating is taking place, energy transfer is taking place

18. Various Forms of Energies • Mechanical energy • Chemical energy • Radiant energy • Electrical energy • Nuclear energy

19. Various Forms of Energies • Mechanical energy  created by a physical movement, it is characteristic of machines in motion; • Chemical energy  energy involving chemical processes (typically oxidation); plants create and store chemical energy from radiant solar energy ; • Radiant energy  EM blackbody radiation emitted by all “visible” objects in the universe; • Electrical energy  generated by the flow of electrical charges along a conducting material; • Nuclear energy  form of energy originating from collisions of atomic nuclei.

20. Activity: Chemical Energy & Energy Balance in the Human Body

21. Activity: Chemical Energy & Energy Balance in the Human Body • Energy Input • Energy values of foods can be estimated based on the content of: • Carbohydrate: 17kJ (4.0 kcal) of energy /g • Protein: 17kJ (4.0 kcal) of energy /g • Fat: 38kJ (9.0 kcal) of energy /g • Alcohol: 29kJ (7.0 kcal) of energy /g

22. Activity: Chemical Energy & Energy Balance in the Human Body Metabolic Energy: Energy needed to maintain life. Based on sex, weight, and age. For a young adult female, the metabolic rate is ~100kJ per day/kg body weight. For a young adult male of the same weight and age, the figure is about 15% higher

23. Activity: Chemical Energy & Energy Balance in the Human Body Muscular Activity: Energy consumed when muscles contract (writing, walking, playing tennis, or even sitting in class). It is typically anywhere from 50% to 100% of the metabolic energy depending on lifestyle: Let’s say the aforementioned female never lifts anything heavier than a textbook.

24. Activity: Chemical Energy & Energy Balance in the Human Body Metabolic Energy + Muscular Activity = kJ/day (kCal / day) So that’s the number of calories or kJ / day you need.

25. Activity: Chemical Energy & Energy Balance in the Human Body Let’s compare the number of calories or kJ / day you need with the energy used by a lightbulb.

26. Activity: Chemical Energy & Energy Balance in the Human Body Metabolic Energy: required will vary depending on environmental conditions.

27. Activity: Chemical Energy & Energy Balance in the Human Body There are 7 billion humans on earth. You now know how many kJ of energy the average human needs per day What is the total energy required for all humans on earth? What percent of the energy given by the sun is this?

29. Key sources of energy used today Future sources of energy

31. In the United States Today the major sources of Energy are Fossil Fuels, Nuclear & Hydroelectric

32. Fossil Fuels Like Natural Gas, Coal & Petroleum are Chemical Sources of Energy octane, a hydrocarbon found in petroleum

33. Only a small percentage of our energy comes from non-chemical sources like hydropower & nuclear

34. Fossil Fuel Reserves(billion oil equiv)

35. Future Carbon Dioxide Emissions ?

36. Conservation of Energy & Sources for the Future: According to the US department of Energy, US currently consumes ~ 1.06 · 1018 J of energy per year • Solar energy  radiant energy from the Sun • Geothermal energy  energy stored beneath Earth’s Crust • Hydrogen energy  hydrogen reacting with oxygen releases • clean energy (water is by-product)

37. Alternative Energy Sources  SOLAR TECHNOLOGY Solar Thermal : (100kW to 30mW power supply) Pro: clean. Con: unstable energy production (sunlight less than 50% of time), low energy efficiency, currently heat is taken up by oil and converted into steam to run turbines, the efficiency is 50%, which could be improved by using new material as heat storage media. Geographic limitation - needs large area to install (only 50% of the total area can be used for solar panels).

38. What controls local climate?What makes it variable? differential regional heating due to Earth’s spherical surface: the same amount of radiation is spread over larger surface in north and south latitudes vs. at the equator.

39. Atmospheric Circulation sets up convection currents Coriolis force: due to rotation of the earth acts at right angles to the direction of motion (deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere)

40. Alternative Energy Sources  SOLAR TECHNOLOGY Wind power: (modern windmill ~2 mW power supply) Pro: clean (no CO2), cheap to run (comparable to burning coal taking into account of carbon tax in the future). Con: expensive to set-up, intermittent productivity, hard to store resulting energy, geographic limitation due to space. If we scale up the current production by 80 times to make up for 1 wedge of carbon reduction (Socolow and Pacala 2006), it will likely interfere with the ecosystem and maybe even the climate system by changing wind pattern.

41. Alternative Energy Sources  SOLAR TECHNOLOGY Bio-fuel: Biofuel is defined as solid, liquid or gas fuel derived from relatively recently dead biological material and is distinguished from fossil fuels, which are derived from long dead biological material. There are two common strategies of producing agrofuels. One is to grow crops high in sugar, and then use yeast fermentation to produce ethyl alcohol (ethanol). Second is to grow plants that contain high amounts of vegetable oil, such as oil palm, soybean. When these oils are heated, their viscosity is reduced, and they can be burned directly in a diesel engine, or they can be chemically processed to produce fuels such as biodiesel.

42. Alternative Energy Sources  SOLAR TECHNOLOGY Bio-fuel: Pro: readily applicable, use unlimited source of solar energy. Con: With the current technology and specific situation in the US, biofuel remain expensive, harms the ecosystem and still produce CO2. Brazil and India could benefit from extracting ethanol from sugarcane that has much higher sugar content than corn, which is the main biofuel crop in the US.

43. Alternative Energy Sources  GEOTHERMAL ENERGY making use of Earth’s internal heat geyser

44. Alternative Energy Sources  HYDROGEN TECHNOLOGY Hydrogen economy: (100kW to 30mW power supply) Pro: more efficient than fossil fuel for the same amount of energy output. Coal gasification has incentive due to the large reserve in the US and theoretically it’s cleaner than directly burning coal. Con: hard to generate, hard to carry around, and traditional production methods using fossil fuel still generates CO2 by product. Coal gasification plants could generate hydrogen much cheaper (through bring coal to 1300-1400 °C and react it with oxygen to generate CO, H2 and CO2,or called syngas), given that the CO2 generated can be captured and stored properly. Or the most common technology is steam methane reforming (SMR) which uses reaction between hot steam (1000 °C) and methane to make CO2 and H2. But problems remain as how to store hydrogen in automobiles.

45. Alternative Energy Sources  HYDROGEN TECHNOLOGY ? Hindenburg disaster, 1937

46. Energy per gram