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Lectures 1-2: Estimates, Energy Use, Wind, Cars
- 1. Renewable Energy NeilGreenham ncg11@cam.ac.uk
- 2. Aims • Todevelop the skills to be quantitative about energy generation, storage and use • Order of magnitude estimates from simple physics • To understand the physics/chemistry/materials science behind some (non- PV) renewable energy technologies, for example • Hydrogen • Batteries • Biofuels
- 3. Absent Friends • Prof. David MacKay • Chief Scientific Adviser, Department of Energy and Climate Change (2009-2014) • Regius Professor of Engineering The book: • Available at all good bookshops • Free online at http://www.withouthotair.com/
- 4. Water-Powered Car MightBe Available by 2009 “Forget cars fuelled by alcohol and vegetable oil. Before long, you might be able to run your car with nothing more than water in its fuel tank. It would be the ultimate zero-emissions vehicle. While water is not at first sight an obvious power source, it has a key virtue: it is an abundant source of hydrogen, the element widely touted as the green fuel of the future.” http://www.newscientist.com/article/mg19125621.200-a-fuel-tank-full-of- water.html?full=true
- 5. Nuclear versus Wind “If we’re going to cut greenhouse gases by 60%, there’s no other possible way of doing that except through renewables” “Anybody who is relying on renewables to fill the energy gap is living in an utter dream world and is, in my view, an enemy of the people “We have a huge amount of wave and wind” “Nuclear is a money pit” Anne Leslie, Journalist Sir Bernard Ingham, former press secretary to Margaret Thatcher Michael Meacher, former environment minister We need numbers, not adjectives!
- 6. What is inthe course? Lectures 1-2 Lectures 5-6 • Estimates • Energy use • Wind • Cars • Hydrogen • Storage • Batteries • Heating and cooling • Exergy • Solar thermal Lectures 3-4 • Energy and charge transfer • Photosynthesis • Biofuels Lectures 7-8
- 7. Rate of energyuse of average UK person? kW kW h day-1
- 8. Some answers NB.Electricity use ~16 kWh/d/person 106
- 9. Possible UK renewableenergy sources
- 10. Some answers NB.Electricity use ~16 kWh/d/person 103 Realistic renewables?
- 11. 53 TWh/year =2.3 kWh/person/day Digest of United Kingdom energy statistics (DUKES) Current renewables (2013) Hydro Landfill Bio PV Onshore wind Offshore wind
- 12. How many windturbines does it take to run a car? Average family car, 33 m.p.g = 12 km per litre Distance travelled per day: 50 km Wind turbine diameter: 25 m Average wind speed: 6 m s-1
- 13. Wind David Cameron’schimney
- 14. Microwind An Ampair'600 W' micro-turbine. The average power generated by this micro-turbine in Leamington Spa is 0.037 kWh per day (1.5 W)
- 15. Real data –27 m turbines, Norfolk (‘225 kW’) Photo by Andrew Dunn Average output (1 turbine): 42 kW
- 16. Refinements? Betz’s law 328vdPower πρ= ? Best power when vafter = vbefore/3 328590vdPower πρ.max= In practice, more like 0.5 ⇒ 35 kW
- 17. Wind power perperson in UK? Spacing ~ 5 times diameter • Cover 10% of UK • Population 60m • Area 244 000 km2
- 18. Cars Where doesthe energy go? Why does a car do 33 m.p.g.?
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- 21. Efficient transport • Have small frontal area per person • Have small weight per person • Convert energy efficiently • Go slowly • Go steadily
- 22. Solar power perperson in UK? 10% of land area
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- 24. 600 km ×600 km, 15 W/m2 ⇒ 1 billion people at 125 kWh/d 145 km × 145 km, 15 W/m2 ⇒ UK population at 125 kWh/d
- 25. Just electricity? Eachblob 1500 km2 Half filled at 15 W/m2 ⇒ 10 GW average per blob 65 blobs ⇒ 1 bn people at 16 kWh/d each
- 26. HVDC transmission 2GW 3.1 GW, 1360 km 1.9 GW, 1420 km 0.7 GW, 580 km
- 27. HVDC cables Finland– Estonia 350 MW in 2 cables Photos: ABB