0 1 00:00:01,960 --> 00:00:14,010 Let's start with energy conversion as I mentioned earlier energy appears in Nature in several forms. 1 2 00:00:14,130 --> 00:00:23,310 We human make energy work for us by converting it from oneform to another form. 2 3 00:00:24,090 --> 00:00:34,100 Let's consider fossil fuel. How fossil fuel are converted into other forms of energy. 3 4 00:00:35,080 --> 00:00:45,840 I will show that in the following simple diagram by burning fossil fuel roughly of 90 percent 4 5 00:00:46,170 --> 00:00:53,120 of the chemical energy is converted into heat using heat engine. 5 6 00:00:53,160 --> 00:00:57,800 The thermal energy can be converted into mechanical energy 6 7 00:01:01,490 --> 00:01:08,580 heat engine have a conversion efficiency of 60 percent. 7 8 00:01:08,910 --> 00:01:19,970 The far majority of the current cars and trucks are based on this principle. mechanical energy can be 8 9 00:01:19,970 --> 00:01:33,340 converted into electricity using electric generator which has efficiency of 90 percent this show that 9 10 00:01:34,720 --> 00:01:45,340 in all process steps, making efficiency out of fossil fuel at least 50 percent of initial available 10 11 00:01:45,430 --> 00:01:57,980 chemical energy is lost in the various conversion steps chemical energy can be directly converted into 11 12 00:01:58,130 --> 00:02:01,130 electricity using something. 12 13 00:02:01,740 --> 00:02:13,900 called fuel cell. the most common fuel used in fuel cell technology is hydrogen chemical conversion efficiency 13 14 00:02:13,990 --> 00:02:26,370 is 60%. A regenerative fuel cell operates in the reverse mode and converts electrical energy into chemical energy 14 15 00:02:26,370 --> 00:02:36,810 electrical energy into chemical energy such as an operation is called electrolytes 15 16 00:02:39,530 --> 00:02:49,820 and the device operated in such a mode is called electrolyzer. 16 17 00:02:49,820 --> 00:02:59,110 hydrogen electrolyzers of 50-80% have been reported. 17 18 00:03:02,540 --> 00:03:11,850 Another route of making electricity is based on an alternative 'fuel' , nuclear energy. 18 19 00:03:11,990 --> 00:03:21,890 Nuclear energy is the energy generated in nuclear fission reactions and generates heat as well. 19 20 00:03:23,190 --> 00:03:31,750 This can be converted in electricity using the just introduced heat engines and electric generators. 20 21 00:03:34,130 --> 00:03:41,090 Next, we will look at alternative energy conversions, which are not based on 21 22 00:03:41,090 --> 00:03:41,510 fuels. 22 23 00:03:44,810 --> 00:03:48,360 hydroelectricity is one example. 23 24 00:03:48,630 --> 00:03:59,460 This potential energy of rainwater falling in mountain area or elevated is converted into mechanical 24 25 00:03:59,460 --> 00:04:05,720 energy using dense using so-called tidal pools. 25 26 00:04:06,040 --> 00:04:16,830 The potential energy stored in tidal can also be converted to mechanical energy the kinetic energy of 26 27 00:04:16,830 --> 00:04:22,280 wind can be converted into mechanical energy using windmills. 27 28 00:04:26,180 --> 00:04:31,570 Finally solar energy can be converted into electricity as well. 28 29 00:04:32,180 --> 00:04:39,800 If solar light is directly converted into electricity using a devices based on semiconductor material 29 30 00:04:40,100 --> 00:04:43,430 we call it photovoltaics. 30 31 00:04:43,820 --> 00:04:46,040 Photo means light. 31 32 00:04:46,300 --> 00:04:49,010 voltaic means electricity. 32 33 00:04:49,010 --> 00:05:02,490 Typically the efficiency of most commercial modules are the range between 15 to 20 percent. solar light 33 34 00:05:02,490 --> 00:05:06,020 can also be converted into heat. 34 35 00:05:06,030 --> 00:05:11,340 This is what we call it solar thermal energy 35 36 00:05:13,940 --> 00:05:25,230 example are heating of water flowing through a block observable material that is heated in sunlight. 36 37 00:05:25,340 --> 00:05:30,010 This heat can be converted into electricity again. 37 38 00:05:31,120 --> 00:05:42,010 Using the heat engine as the conversion efficiency of heat engine strongly depends on temperature and 38 39 00:05:42,010 --> 00:05:53,170 concentrated solar power system are used to generate electricity so solar heating using so-called high 39 40 00:05:53,170 --> 00:05:54,870 temperature collectors. 40 41 00:05:56,190 --> 00:06:07,550 Next to generating heat and electricity solar energy can be converted into chemical energy as well. 41 42 00:06:09,330 --> 00:06:17,010 Next to generating heat electricity solar energy can be converted into chemical energy as well. 42 43 00:06:17,010 --> 00:06:28,410 This is what we refer to as a solar fuel. this is possible by using photovoltaics and regenerative 43 44 00:06:28,480 --> 00:06:29,370 fuel cell. 44 45 00:06:30,300 --> 00:06:39,490 But solar light can be also directly converted to fuel using photo electrochemical devices. 45 46 00:06:41,800 --> 00:06:49,050 This means we can convert solar energy into electricity, heat and chemical energy 46 47 00:06:53,140 --> 00:07:03,710 Renewable energy sources. renewable energy sources are the energy sources that are replenished by nature. 47 48 00:07:03,970 --> 00:07:13,210 Process at a rate of comparable or faster than its rate of consumption by Humans 48 49 00:07:16,340 --> 00:07:19,420 hydro wind solar energy. 49 50 00:07:19,900 --> 00:07:31,490 All our renewable energy sources fossil fuel and nuclear energy are not renewable energy as their fuel 50 51 00:07:31,970 --> 00:07:39,510 are consumed faster than they are generated in nature from all energy sources. 51 52 00:07:39,590 --> 00:07:54,560 Based on chemical , thermal, nuclear, hydro, wind, solar, geothermal roughly one-third is being used to 52 53 00:07:55,070 --> 00:07:56,480 generate electricity 53 54 00:07:59,650 --> 00:08:10,670 electricity is a form of electrical energy that can be easily and cheaply transported with relatively small 54 55 00:08:10,670 --> 00:08:11,480 losses. 55 56 00:08:11,660 --> 00:08:22,190 through an electric grid we might not realize it anymore but electricity has made today's modern society 56 57 00:08:22,190 --> 00:08:23,800 possible. 57 58 00:08:23,810 --> 00:08:28,700 It's as simple of modern life and progress. 58 59 00:08:28,700 --> 00:08:35,350 Electricity has been practically used for more than a hundred years now. 59 60 00:08:37,810 --> 00:08:48,430 Electricity provide us the energy to cook food, to wash and to do laundry illuminate houses and street 60 61 00:08:48,790 --> 00:08:58,980 watch TV, air conditioning and heat work on computer , surfing the Internet. 61 62 00:08:59,010 --> 00:09:05,730 Access to electricity determines the living standards of humans. 62 63 00:09:05,900 --> 00:09:14,270 We must realize that at around one point two billion out of there 7 billion people worldwide still don't 63 64 00:09:14,270 --> 00:09:24,560 have access to electricity grid electricity worldwide is mainly generated from oil, coal, gas, nuclear 64 65 00:09:24,890 --> 00:09:27,020 or hydro power. 65 66 00:09:27,050 --> 00:09:36,320 Here we see the relative contribution of these resources to global electricity generation 2007 66 67 00:09:38,630 --> 00:09:44,150 65 percent of electricity is coming from fossil fuel. 67 68 00:09:44,610 --> 00:09:49,970 as shown. where coalis dominant contributor. 68 69 00:09:50,460 --> 00:10:01,740 Unfortunately coal produce roughly 2 times more carbon dioxide being generated unit of energy in reference 69 70 00:10:01,740 --> 00:10:12,490 to gas. nuclear power is responsible for 60 percent off the wall its electricity generation and the 70 71 00:10:12,490 --> 00:10:22,840 hydro power and hydro power was 90 percent by far the largest contributor among the renewable energy 71 72 00:10:22,840 --> 00:10:33,370 sources in their conversion from chemical and nuclear power to electricity. 2/3 of the energy is 72 73 00:10:33,370 --> 00:10:34,370 lost. 73 74 00:10:34,450 --> 00:10:45,910 1/3 end up form electricity means 40 percent of electrical energy is used in the residential purpose 74 75 00:10:46,930 --> 00:11:02,370 and 47 percent is used in industry and 13 percent of energy is lost in transmission as you can see 75 76 00:11:02,820 --> 00:11:11,190 in 2007 transport didn't play a significant role in electricity consumption. 76 77 00:11:11,340 --> 00:11:20,820 However it expected that transport related electricity consumption will increase in the coming decade 77 78 00:11:21,600 --> 00:11:22,320 as well. 78 79 00:11:24,500 --> 00:11:36,690 In 2007, 22 hundred tera watt hour of electricity was generated world wide if we consider 79 80 00:11:37,380 --> 00:11:40,550 0.5 gigawatt nuclear power plan. 80 81 00:11:40,620 --> 00:11:48,590 It's means we need about 5000 nuclear power plants at around the world. 81 82 00:11:48,600 --> 00:12:02,240 If our electricity needs the will it be fully covered by nuclear power realize that sources for electricity 82 83 00:12:02,240 --> 00:12:14,390 generation might differ from country to country for example In the Netherlands, electricity generation 83 84 00:12:14,440 --> 00:12:27,110 Heavily depends on the local gas resource and in Brazil hydro-electricity is the most important resource. 84 85 00:12:27,620 --> 00:12:30,010 in the last 100 years 85 86 00:12:34,950 --> 00:12:46,220 in the last 100 years that humankind's energy infrastructure heavily relies on fossil fuel. 86 87 00:12:46,310 --> 00:12:56,510 We are quickly using that solar energy of millions and millions of years of cover into chemical energy 87 88 00:12:56,900 --> 00:13:02,910 by photo-process and the stored in the form of gas, coal and oil. 88 89 00:13:05,130 --> 00:13:11,570 How did we do that before the Industrial Revolution. 89 90 00:13:11,850 --> 00:13:22,140 The main source of electrical energy back then was wood and biomass which is secondary forms of solar 90 91 00:13:22,140 --> 00:13:34,850 energy the energy source was replenished in same characteristic time as the energy being consumed in 91 92 00:13:34,850 --> 00:13:37,540 the pre-industrial era. 92 93 00:13:37,710 --> 00:13:43,980 Humankind was basically living on secondary form of solar energy. 93 94 00:13:44,060 --> 00:13:51,330 We are not claiming that since energy consumption was fully sustainable way of living. 94 95 00:13:51,350 --> 00:14:02,570 We have to take in mind that due to increasing population density was already playing a role as the 95 96 00:14:02,570 --> 00:14:05,220 end of first millennium. 96 97 00:14:05,240 --> 00:14:13,360 In Europe the sun has been energy source for all process. 97 98 00:14:13,620 --> 00:14:16,130 on the surface of this planet. 98 99 00:14:16,200 --> 00:14:27,700 Wind is a result of temperature difference in the atmosphere introduced by solar radiation. waves are 99 100 00:14:27,730 --> 00:14:42,590 generated by wind, cloud and rains are initially formed by evaporation of water due to sunlight because 100 101 00:14:42,590 --> 00:14:47,330 the sun is the only real energy source we have. 101 102 00:14:47,330 --> 00:15:01,540 We need to move back again to an era in which we start to utilize the sun to satisfy our energy needs is 102 103 00:15:01,540 --> 00:15:13,240 in the next block, in next section we will introduce you to that technology which is called solar 103 104 00:15:13,250 --> 00:15:19,850 energy specially PVor photovoltaic energy. 104 105 00:15:19,970 --> 00:15:22,450 See you in the next block.