1. R.Carmassi I.T.I. Malignani - Udine HYDROGEN THE FUEL OF THE FUTURE?

2. R.Carmassi I.T.I. Malignani - Udine Hydrogen (H is the chemical symbol) is the most abundant element in our universe. On the Earth surface (land, water, atmosphere)0.88% is hydrogen. This hydrogen is bonded with oxygen, that’s to say it is not good as a fuel It is everywhere: water contains 11.2% hydrogen but… So water has to be splitted up into molecular oxygen (O 2 ) and molecular hydrogen (H 2 ), but this separation requires energy

3. R.Carmassi I.T.I. Malignani - Udine H 2 + 1/2O 2  H 2 O (l) + 286 kjoule One mole of hydrogen (2.02g) reacts with half a mole of oxygen (16.0g) producing one mole of water (18.0g) and 286 kjoule of energy We need the same amount of energy in the electrolysis of one mole of water to produce one mole of hydrogen: 286 kjoule + H 2 O (l)  H 2 + 1/2O 2 Electrolysis is the production of a chemical reaction by passing an electric current through an electrolyte.

4. R.Carmassi I.T.I. Malignani - Udine SO HYDROGEN WILL BE THE FUEL OF THE FUTURE IF ELECTRIC POWER WILL BE AVAILABLE FROM RENEWABLE SOURCES OF ENERGY IN OTHER WORDS, HYDROGEN, MORE THAN A SOURCE OF ENERGY, IS A PERFECT ENERGY CARRIER

5. R.Carmassi I.T.I. Malignani - Udine In the next slides we are going to see an example of hydrogen fuel from a renewable source of energy: the Sun

6. R.Carmassi I.T.I. Malignani - Udine

7. Sunlight is energy in the form of electromagnetic waves In solar cells sunlight is converted to electricity In electrolytic cells water is splitted up into oxygen and hydrogen. Energy is stored in hydrogen (potential chemical energy ) Water is purified (deionized) before electrolysis Hydrogen is dried, compressed, dried again, stored in the dispensing station In a ICE (internal combustion engine) Hydrogen is converted into mechanical energy Pure water is the only waste product of this engine

8. R.Carmassi I.T.I. Malignani - Udine CONCLUSION (fill in the gaps) In the previous slides we have seen: the Sun, …………… (PV) cells producing electric power, electrolytic cells producing hydrogen, a compressing-drying unit to store hydrogen under ………, a filling station in which a pick-up is fuelled with ………. The Sun’s energy is first …………. to electric energy and then …… as chemical energy in hydrogen in pressure tanks. In the pick-up this chemical energy will be converted to …………….. energy. MISSING WORDS converted pressure hydrogen photovoltaic mechanical wind energy stored fuels carriers pollutants water million source hydroelectric biomass

9. R.Carmassi I.T.I. Malignani - Udine CONCLUSION (fill in the gaps) The Sun’s energy is stored as chemical ………. in the photosyntesis as well. Photosynthesis produces indirectly ……… like wood or foods or, after hundreds million years, fossil …….. So fossil fuels and hydrogen are both energy ………, but there are some differences: All fossil fuels, if burned, produce …………… and increase the greenhouse effect; fossil fuels are renewable over a period of ……… years. MISSING WORDS converted pressure hydrogen photovoltaic mechanical wind energy stored fuels carriers pollutants water million source hydroelectric biomass

10. R.Carmassi I.T.I. Malignani - Udine CONCLUSION (fill in the gaps) Hydrogen, if burned, produces only ……,which is non pollutant; hydrogen is renewable over hours if a ……. of electrical power is available. If PV cells, or …………….. power, or electric power generated by …… are used, the hydrogen-water cycle is entirely free of pollutants and doesn’t contribute to the greenhouse effect. MISSING WORDS converted pressure hydrogen photovoltaic mechanical wind energy stored fuels carriers pollutants water million source hydroelectric biomass

11. R.Carmassi I.T.I. Malignani - Udine CONCLUSION In the previous slides we have seen: the Sun, photovoltaic (PV) cells producing electric power, electrolitic cells producing hydrogen, a compressing-drying unit to store hydrogen under pressure, a filling station in which a pick-up is fuelled with hydrogen. The Sun’s energy is first converted to electric energy and then stored as chemical energy in hydrogen in pressure tanks. In the pick-up this chemical energy will be converted to mechanical energy. The Sun’s energy is stored as chemical energy in the photosyntesis as well. Photosynthesis produces indirectly biomass like wood or foods or, after hundreds million years, fossil fuels. So fossil fuels and hydrogen are both energy carriers, but there are some differences: All fossil fuels, if burned, produce pollutants and increase the greenhouse effect; fossil fuels are renewable over a period of million years. Hydrogen, if burned, produces only water, non pollutant; hydrogen is renewable over hours if a source of electrical power is available. If PV cells, or hydroelectric power, or electric power generated by wind are used, the hydrogen-water cycle is entirely free of pollutants and doesn’t contribute to the greenhouse effect. MISSING WORDS Photovoltaic pressure hydrogen converted stored mechanical energy biomass fuels carriers pollutants million source hydroelectric

12. R.Carmassi I.T.I. Malignani - Udine Photovoltaic Cells (also called solar cells) In a photovoltaic cell, light excites electrons to move from one layer to another through semiconductive silicon materials. This produces an electric current. The strength of solar radiation at the outer edge of the earth's atmosphere when the earth is taken to be at its average distance from the sun is called the solar constant, the mean value of which is 1.37 × 10 3 joules per sec per m 2. The intensity of energy actually available at the earth's surface is less than the solar constant because of absorption and scattering of radiant energy as photons interact with the atmosphere. On a bright, sunny day, the sun shines approximately 1,000 watts of energy per square meter of the planet's surface,(in California?) Solar cells convert solar radiation directly into electricity with conversion efficiencies of 30 per cent

13. R.Carmassi I.T.I. Malignani - Udine BRITISH AND AMERICAN UNITS 1 inch= 2.54 cm 1 foot (ft) = 12 inches= 0.3048 m 1 cubic foot (cf)= 28.32 dm 3 1 (UK)gallon= 4.546 dm 3 1 (US)gallon= 3.785 dm 3 1 pound (lb)= 0.4536 Kg 1 pound/square inch (psi) = 6895 Pascal (Pa) = 0.06895 bar joule (j) is the SI unit of work and energy equal to the work done when a force of one Newton moves a distance of a meter. British thermal Unit (Btu) is the energy required to raise the temperature of 1 lb of water by 1°F. Btu is now defined as 1055.06 joules. Calorie (cal) is the energy required to raise the temperature of 1 gram of water by 1 °C 1 calorie = 4.186 joules