1 00:00:05,569 --> 00:00:09,900 Let's start with the first question. What is energy? 2 00:00:09,900 --> 00:00:15,639 I notice that when I ask this question to students, they usually have trouble giving 3 00:00:15,639 --> 00:00:17,950 an exact definition. 4 00:00:17,950 --> 00:00:19,980 And I must say it is not easy. 5 00:00:19,980 --> 00:00:25,960 The scientific definition for energy would be something like: 6 00:00:25,960 --> 00:00:31,849 the capacity of a system to perform work. 7 00:00:31,849 --> 00:00:35,050 We humans use energy to do some work. 8 00:00:35,050 --> 00:00:39,210 We use energy for heating air and water. 9 00:00:39,210 --> 00:00:46,210 We use energy for transportation of people and products by cars, trains, trucks and planes. 10 00:00:46,980 --> 00:00:51,079 We use energy to produce food and products. 11 00:00:51,079 --> 00:00:55,809 We use energy to illuminate houses and streets. 12 00:00:55,809 --> 00:01:04,070 We use energy to watch TV, do our laundry, working on computers and surfing the internet. 13 00:01:04,070 --> 00:01:11,070 At the moment you are consuming energy by watching this video lecture. 14 00:01:11,590 --> 00:01:18,590 Energy appears in many forms in our daily life, like gravitational energy, kinetic or 15 00:01:19,500 --> 00:01:29,000 mechanical energy, electrical energy, heat radiation, wave energy, chemical energy and 16 00:01:29,000 --> 00:01:32,250 nuclear energy. 17 00:01:32,250 --> 00:01:34,899 The total amount of energy is always conserved. 18 00:01:34,899 --> 00:01:41,899 The form of energy may change in time, but the total amount does not change. 19 00:01:42,149 --> 00:01:49,149 This means that if we want energy to work for us, we usually convert it from one form 20 00:01:49,369 --> 00:01:52,090 to another form. 21 00:01:52,090 --> 00:01:56,800 An example is the electric motor, this is a tool in which we convert electrical energy 22 00:01:56,800 --> 00:01:58,590 into mechanical energy. 23 00:01:58,790 --> 00:02:02,180 The unit of energy is joule (J). 24 00:02:02,180 --> 00:02:06,829 Power is the energy per time and is expressed in watts (W). 25 00:02:06,829 --> 00:02:10,220 1 watt is 1 joule per second. 26 00:02:10,220 --> 00:02:16,019 In this course we will use a more practical unit, which is generally used to express the 27 00:02:16,019 --> 00:02:19,250 electrical energy, kilowatthours (kWh). 28 00:02:19,250 --> 00:02:28,250 1 kWh equals the energy of a power of 1 kW being used for 1 hour. 29 00:02:28,299 --> 00:02:34,730 1 kWh equals 3.6 million joules. 30 00:02:34,730 --> 00:02:40,219 The world as we know today is based on the capability of humans to convert energy 31 00:02:40,219 --> 00:02:43,329 from one form to another form. 32 00:02:43,329 --> 00:02:49,239 The most prosperous and technologically developed nations are also the ones which have access 33 00:02:49,239 --> 00:02:53,780 to and are using the most energy per capita. 34 00:02:53,780 --> 00:03:00,160 Therefore, many people believe that the biggest challenge for human kind in this century is 35 00:03:00,160 --> 00:03:03,060 tackling the energy problem. 36 00:03:03,060 --> 00:03:06,470 Why do we have a problem? 37 00:03:06,470 --> 00:03:11,840 The first challenge the human kind is facing is a supply-demand problem. 38 00:03:11,840 --> 00:03:14,810 The demand is constantly growing. 39 00:03:14,810 --> 00:03:20,979 The world population is still rapidly growing, and some studies predict a world population 40 00:03:20,979 --> 00:03:27,979 of 9 billion around 2040 in reference to the 7 billion people living on this planet today. 41 00:03:29,690 --> 00:03:35,579 All these people will need energy, which increases the global energy demand. 42 00:03:35,579 --> 00:03:42,579 In addition, the energy consumption per capita is linked to the living standard of a country. 43 00:03:42,699 --> 00:03:49,699 In 2010, in the United States (US) around 230 kWh of energy per capita per day was used, 44 00:03:50,660 --> 00:03:56,510 whereas countries in Africa, like Nigeria, only used one tenth of this energy, 45 00:03:56,510 --> 00:04:02,590 around 23 kWh per day per capita. 46 00:04:02,590 --> 00:04:07,739 In this graph you see the living standard expressed in human development index. 47 00:04:07,739 --> 00:04:11,070 The darker the color, the more developed the regions are. 48 00:04:11,070 --> 00:04:15,949 However, the light colors in this figure are getting darker by the year. 49 00:04:15,949 --> 00:04:23,660 In many countries the living standard is rapidly increasing like China and India, where approximately 50 00:04:23,660 --> 00:04:28,030 2.5 billion people are living. 51 00:04:28,030 --> 00:04:35,030 These people represent more than a third of the world's population. 52 00:04:35,440 --> 00:04:43,220 Both increasing world population and increasing living standards will increase the energy demand. 53 00:04:43,680 --> 00:04:49,040 The International Energy Outlook 2013 predicts that the energy consumption will increase 54 00:04:49,040 --> 00:04:56,040 by 56% by 2040 in reference to 2010. 55 00:04:56,790 --> 00:05:02,010 The increasing demand in energy has economic impact, as well. 56 00:05:02,010 --> 00:05:07,480 If there is more demand for a product, while supply does not change much, the product will 57 00:05:07,480 --> 00:05:09,870 get more expensive. 58 00:05:09,870 --> 00:05:14,110 This is also true for energy. 59 00:05:14,110 --> 00:05:20,490 As an example we show a plot of the annual averaged price for an oil barrel, normalized 60 00:05:20,490 --> 00:05:24,960 to the value of the 2008 US dollar. 61 00:05:24,960 --> 00:05:31,050 First, you can see that prices went up during the oil crisis in the 70s. 62 00:05:31,050 --> 00:05:38,050 In this decade some countries stopped producing and trading oil for a while. 63 00:05:38,160 --> 00:05:44,820 The second era of higher oil prices started at the beginning of this millennium. 64 00:05:44,820 --> 00:05:50,520 Due to the increasing demand from new growing economies, 65 00:05:50,580 --> 00:05:53,850 the oil prices have been significantly increased. 66 00:05:54,050 --> 00:06:00,670 A second challenge that human kind is facing is related to the fact that our energy infrastructure 67 00:06:00,670 --> 00:06:06,560 heavily depends on fossil fuels like oil, coal and gas. 68 00:06:06,560 --> 00:06:13,290 Fossil fuels are nothing but millions and millions of years of solar energy stored in 69 00:06:13,290 --> 00:06:16,170 the form of chemical energy. 70 00:06:16,170 --> 00:06:22,860 The problem is that humans deplete these fossil fuels faster than they are generated 71 00:06:22,860 --> 00:06:26,620 through the photosynthetic process in nature. 72 00:06:26,620 --> 00:06:32,660 Therefore, fossil fuels are not a sustainable energy source. 73 00:06:32,660 --> 00:06:38,639 In the coming century we will see that we are running out of the oil and gas reserves 74 00:06:38,639 --> 00:06:44,050 if we continue our current rates of consumption. 75 00:06:44,050 --> 00:06:49,980 Another barrier is that it is technological more challenging to get the fossil fuels out 76 00:06:49,980 --> 00:06:52,340 of the reserves currently left. 77 00:06:52,340 --> 00:06:56,950 Governments and companies are willing to take higher risks, like we have seen in 78 00:06:56,950 --> 00:07:00,310 the Gulf of Mexico spill in 2010. 79 00:07:00,810 --> 00:07:07,810 A third challenge is that by burning fossil fuels we produce the so-called 80 00:07:08,030 --> 00:07:11,860 greenhouse gases (GHG) like carbon dioxide. 81 00:07:11,860 --> 00:07:18,860 The additional carbon dioxide created by human activities is stored in our oceans and atmosphere. 82 00:07:18,919 --> 00:07:25,560 Here you see the increase in carbon dioxide concentration in the Earth's atmosphere up to 2000. 83 00:07:28,389 --> 00:07:33,480 Most scientists think the increase in carbon dioxide is responsible for the global warming 84 00:07:33,480 --> 00:07:37,510 and climate change, which can have drastic consequences of the 85 00:07:37,510 --> 00:07:41,240 habitats of many people. 86 00:07:41,240 --> 00:07:47,220 Therefore, human kind is looking for alternative energy sources, like solar and wind.