1. Renewables definition Renewable Energy is energy obtained from the natural and persistent currents of energy in the environment e.g. sunshine, wind, rainfall ------------------------------------------------------- considered “Green Energy” intrinsically non-polluting ------------------------------------------------------- “Direct” RE from natural environment “Indirect” RE from society’s wastes

2. Solar radiation Geothermal heat Gravitational potential Reflected 50Absorbed 120 absorbed as heat water phase change hydro flow kinetic wind waves photon interaction photosynthesis tides heat Total renewable energy flows through the biosphere: unit 10 15 W (10 9 megawatt) 80 40 0.3 0.03 3 0.001 radiation to outer space

3. Solar radiation per person Geothermal heat Gravitational potential Reflected 8,000 kWAbsorbed 20,000 kW absorbed as heat water evaporation, rain & hydro flow wind, waves photosynthesis (plants, crops) tides heat Per capita Renewable energy: kilowatt per person on Earth i.e. solar is equivalent of 20,000 one-bar electric heaters for each man, woman and child 13,000 kW 7,000 kW 50 kW 5 kW 500 kW 0.2 kW radiation to outer space

4. Solar radiation Geothermal heat Gravitational potential Solar water heaters, Solar buildings Hydro-electricity; very large (GW) to very small (100 W) scale wind turbines, wave power Fuel wood, biomass biodiesel, ethanol, wastes Tidal range power; e.g. Severn estuary & Tidal stream power heat pumps Renewable energy technologies Photovoltaic solar cells

5. Renewable energy technologies for heat, electricity, transport fuels solar buildings solar water heating solar thermal electricity solar cell photovoltaic electricity solar driers solar refrigeration hydroelectricity micro-hydro wind turbines wave power photosynthesis biomass crops pyrolysis biofuel oils biogas sewage gas urban waste geothermal heat tidal range tidal stream power fuel cells

6. Scaling: energy fluxes configure the technologies bright sunshine 1 kW/m 2 brisk wind (10 m/s) 1 kW/m 2 house heating boiler 10 kW/m 2 coal power station boiler 100 kW/m 2 nuclear power boiler 1,000 kW/ m 2

7. So, for renewables…………………... potential very large and sufficient free (no cost) in the environment but dispersed and variable need to capture, deliver, utilize and store encourages local enterprise & cash flow manufacturing growth from environmental push and commercial pull but….RE plant is relatively large so…..RE plant is capital intensive

8. Conclusions: renewables … proven technologies most are in the market place credit for environmental and sustainable benefits favoured by world, European, national & local policies but still much to do