1. Physics perspective of environment

2. What is energy? Work (Moving an object) An object in motion Field with an object (e.g. An object put at higher place) Heat Light Etc.

3. Making energy Making heat by burning oils or coals, etc. Utilizing steam or combustion to create a physical force Using the force to create electricity Utilizing motions in nature to create electricity Using chemical reactions to create electricity Utilizing quantum reactions to create electricity Using nuclear reactions to create heat

4. Engine system 1. Intake air and vaporized fuel 2. Compress the air-fuel mixture 3. Ignite the gas 4. Exhaust fumes To be repeated

5. Energy cycle system (General concept of engine) Rotating turbines / crankshaft, etc.

6. Ecology and energy circulation

7. Introduction to thermodynamics The zeroth law  Thermal equilibrium and principle of thermometer The first law  Energy conservation The second law  Entropy The third law  Infinite processes to reach absolute zero degree

8. Zeroth law of thermodynamics Systems A and B are thermal equilibrium with system C. Namely, A and B are equilibrium with each other. This process defines temperature.

9. Thermal equilibrium Thermal equilibrium is not uniformity of heat, but there is not heat flows between systems.

10. Latent heat 1 When a substance transforms into a different phase, the heat flows between the phases without change of the temperature. The heat that plays this role is known as latent heat.

11. Latent heat 2 When ice melts, the heat is absorbed by 80 cal per gram.  That is why ice can keep things refrigerated. When water is vaporized, the heat radiates 540 cal per gram.  When sweat dries out, the surface of your skin is significantly cooled down.

12. First law of thermodynamics The internal energy of a system transforms into heat flows. As a system, the internal energy and heat flow are conserved. |Q T – Q 1 | = |Q 2 – Q T |

13. Second law of thermodynamics In an isolated system, the entropy cannot decrease.  Energy and substances are diffused. The work done by heat cannot generate the same amount of internal energy.

14. Entropy 1 Entropy id defined as the change of the heat energy divided by the absolute temperature. The process of heat flow entails the increase of entropy The entropy after the heat flow is larger.

15. Entropy 2 When vapor becomes water by cooling, it looks like the entropy decreases. This is because it is an open system. In terms of the larger system, the entropy increases by the heat radiation.

16. Third law of thermodynamics As the temperature approaches zero, the entropy also approaches zero at thermodynamic equilibrium. In principle, it is impossible to reach absolute zero.

17. Steam engines This was started from the transformation of energy sources. [Wood  Coal] People needed innovation of technology to utilize coals effectively. T. Savery, T. Newcomen, and J. Watt developed steam engines with energy from coals. [The end of 17 to the middle of 18 centuries]

18. Newcomen’s engine 1. Burn the coals. 2. Boil the water. 3. The steam raise the pressure of the cylinder to lift the piston. 4. Feed water into the cylinder. 5. Then it pulls down the piston by lowering pressure.

19. Watt’s engine 1. Burn the coals. 2. Boil the water. 3. The steam raise the pressure of the cylinder to lift the piston. 4. The steam goes down into the condenser and it is cooled down to become water. 5. Then it pulls down the piston by lowering pressure.

20. Work and energy Work = force  distance Kinetic energy = 1/2  mass  speed 2 Gravitational potential energy = mass  grav.accel.  height You can find other energy, such as wind, water flows, chemical reactions, etc. These are exchangeable each other. Energy  Work

21. First law of thermodynamics revisited (Energy conservation) In a system, sum of all the work and energy is constant. They compensate each other; for example, more force with less distance, and less force with more distance to move an object. Without having energy from outside, the system cannot continue to work.

22. Entropy and work Entropy increases at the direction of the thermal processes. Work capability can be associated with the entropy.

23. Heat as energy The heat created from electricity is: Q=RI 2 t where Q, R, I and t are heat, resistance, current and time. Heat itself is energy: E = kT where k and T are Boltzmann const. and temperature. 1 calorie = 4.19 joules

24. Carnot cycle 1 The low grade heat source plays an important role. All the given heat cannot be used only for the work because the engine is stopped. Part of the given heat is absorbed into the law grade heat source.

25. Carnot cycle 2 This is a reversible system. (repeatable) The efficiency is given only by T 0 and T 1. This system includes the direction of the heat flow.

26. Human-activity system as an engine Excess of each process may cause problems… Depletion of natural resources Destroying ecology Waste disposal problems Pollutions Destroying ecology

27. Human activity and environmental structure Natural resources will be depleted when human consumption is more than the quantity that nature can produce. Other biological systems play very important roles to keep various equilibria on the earth. Environments need to have margins to neutralize exhausted products to manage entire ecology.

28. Water as an important factor in environment 1 Water is harder to be heated up and harder to be cooled down. (= high specific heat: 4186 J/kg K) This provides a stable environment on the earth.

29. Water as an important factor in environment 2 The vaporized water becomes lighter to go up. Then, it gets cooled there and falls as rain or snow. Due to the latent heat and radiation, this process Remove excess heat from the earth.

30. Bio-system and its cycle The system is based upon sun shine and water. Plants produce carbohydrates (sugars) to feed animals. Animals’ excretory substances are degraded by bacteria. The substances degraded by bacteria are used for plants. This process repeats.

31. Heat death of the universe 1 If the entropy keeps on increasing, every system will become equilibrium, which is called heat death. However, an open system exchanges lower and higher entropies. Entropy keeps increasing in a closed system.

32. Heat death of the universe 2 In the universe, the entropies flow as in the structure:

33. Ecological systems 1 Biological creatures inhabit  10 km (6.21 miles) from the surface of the earth. Plants produce carbohydrates by photosynthesis. Animals consume them and excrete as in a different substances. Bacteria and fungi biodegrade the substances and carcasses for plants.

34. Ecological systems 2 Bacteria play an important role for the cycle. especially for the circulation of nitrate

35. Ecological systems 3 Bacteria biodegrade carbons and nitrides in detritus into CO 2 (carbon dioxide), NH 4 + (ammonium ion), and NO 3 - (nitrate ion). Amount of CO 2 crated by bacteria is exactly the same amount consumed by plants. One gram of soil contains about 1 billion of bacteria (1 million kinds).* * Computational improvements reveal great bacterial diversity and high metal toxicity in soil. J. Gans, et al. Science, 309, 1387-1390 (2005)

36. Photosynthesis 1 A simple description of photosynthesis: Breathing: CH 2 O + O 2  CO 2 + H 2 O Photosynthesis: CO 2 + H 2 O  CH 2 O + O 2 CH 2 O is the product from photosynthesis.

37. Photosynthesis 2 The carbohydrate produced by photosynthesis is glucose, C 6 H 12 O 6. 6CO 2 + 12H 2 O  C 6 H 12 O 6 + 6O 2 + 6H 2 O Many of glucose get bonded to become starch. Starch is multiple glucose missing water: (C 6 H 10 O 5 ) n

38. Photosynthesis 3 The entropy of carbon atoms seems decreased by photosynthesis, but the entropy of the larger system is surely increasing. How? Remember that vaporization of water makes the entropy increased.

39. Photosynthesis 4 The actual chemical reaction of photosynthesis is: 6CO 2 +6H 2 O+6H 2 O  C 6 H 12 O 6 +6O 2 +6H 2 O The H 2 O of right hand side radiates heat due to the latent heat. (The increase of entropy) for photo- synthesis liquidvapor

40. Entropy and photosynthesis To produce glucose by photosynthesis, it needs sufficient water not only for the chemical reaction but also for the “exit” of entropy. It is said that the imbalance of the entropy- circulation system may cause desertification or other malfunctioning of plant systems.

41. Water on the earth 1 Specific gravity (S.G.)  In general, most of S.G. of substances become larger (i.e. heavier) when they are refrigerated, but water is different.  Water has S.G., 1.0 when it is at 4 degrees of Celsius. (the heaviest)  Temperature of water, T w. T w =0  S.G.=0.999; T w =50  S.G.=0.988; T w =100  S.G.=0.958.  The S.G. of ice is 0.917.

42. Water on the earth 2 The S.G. of water does not depend on the temperatures significantly. The S.G. of ice is smaller than the liquid phase of water; therefore, the ice can float. This makes water circulate faster and more easily; thus, it has generated variety of biological species.