The document presents an overview of green power, defined as energy sources with minimal greenhouse gas emissions, including hydro, wind, biomass, solar, and geothermal. It discusses the increasing interest in renewable energy driven by concerns over fossil fuel dependency and environmental impacts, noting that renewable market penetration is accelerating. The conclusion emphasizes the growing importance of renewable energy technologies for engineers and policymakers as global warming concerns intensify.

1. GREEN POWER EET 3700 Presented by: Dan Ehlke

2. OVERVIEW What is Green Power? Why Green Power? Kinds of Green Power Hydro Wind Biomass Solar Geothermal Conclusion

3. WHAT IS GREEN POWER? “ Green” Power: any energy source with a negligible impact on greenhouse gas emissions. Includes: hydro, wind, biomass, geothermal, & solar

4. WHY GREEN POWER? In the 1970s & 1980s the interest in green power was driven by the goal of replacing fossil fuels after the first oil shock in the mid 1970s Now, the broader goal includes minimizing the emission of CO2.

5. WHY GREEN POWER? There are considerable external costs for electricity from fossil fuels that someday must be taken into account as concerns about global warming become real. While contributions from renewable energy is small, with the exception of hydro, their market penetration is growing at a much faster rate than from conventional sources.

6. WHY GREEN POWER? Competition: green option as a means of differentiating their service & winning customer loyalty. More than 190 electric utilities offer green power in the U.S. 50% of consumers surveyed are willing to pay an extra $15 per month to receive green electricity.

7. HYDRO Most mature renewable source of electricity around the world. 700,000 MW contributes 21% of electricity worldwide (year 2000) Negetive: Limited exploitable sites Potential damage to environment – Indiginous people of developing countries.

8. HYDRO Types Impoundment Allows operators to stabilize power with fluctuating water levels. Reduce flooding River – flow. Relies on river flowing water to keep producing electricity.

9. HYDRO Impoundment type Water turns turbines at bottom of the penstock (powerhouse) Turbine attached to series of gears which increase the speed of rotation. When there is too much water, the spillway allows extra water to bypass the penstock.

10. WIND Second most popular source of green power. 17,500 MW worldwide (70% of which was in Europe) in 2000 However, in 2001 1,695 MW was added in the U.S. making it the second largest concentration of wind power in the world.

11. WIND HAWT: Horizontal-axis wind turbine Axis about which blades rotate is horizontal Higher height for greater wind speeds All commercially available wind turbine generators. Utility-scale Utility-scale typically have greater requirements Solid towers, concrete pads, built on-site. Individual-scale VAWT: Vertical-axis wind turbine Axis about which blades rotate is vertical Must be mounted closer to the ground

12. WIND The nacelle houses the gearbox, generator, and associated controls. Rotor blades pitch angle may be controlled to optimize energy capture with changing wind speeds Prevent damage past design rotational speed Rounded tips reduce minimum speed needed to start, and increases aerodynamic efficiency Cut-in speed: wind speed necessary to begin producing electricity (as low as 3 m/s)

13. BIOMASS Plant matter, trees, grasses, agricultural crops or other biological materials. 14,000 MW of annual worldwide generation capacity. The U.S. is the largest biomass generator in the world with 7,000 MW. Expected to grow more than 30,000MW by 2020. Developing countries: availability of cheap feedstock Bio Materials steam turbine Bio Materials fuel gas engine, turbine or fuel cell Biomass gas may also be integrated into industrial manufacturing plants for power, heat or cooling needs.

14. SOLAR -THERMAL Concentrating sunlight and trapping its’ heat to produce steam 3 types: Central receiver 2,000 sun-tracking heliostats to single collection vessel Molten salt flowing through the receiver and transferred to a hot salt storage tank, then steam generator when needed. Trough based Mirrors are parabolic Tracks the sun on one axis due to linear focus Lower concentration factor Lower cost potential Dish based Point focused – 2 axis tracking

15. SOLAR - PHOTOVOLTAIC 800 MW worldwide capacity Fundamental unit: cell Material: semiconductor material Gallium arsenide Crystalline silicon Amorphous silicon Available current is a function of cell area & light intensity. Formed into modules (series & parallel configs) to obtain greater voltage & current.

16. GEOTHERMAL Heat at the core of the earth exploited to produce electricity through steam. 7,974 MW generated worldwide (1999) Capital intensive: enough steam supply wells have to be drilled up-front to provide the full plant capacity at startup.

17. CONCLUSION As the concerns about the availability & environmental impacts of fossil fuels become more wide spread, the interest on environmentally benign renewable energy technologies will surely take center stage among engineers & policymakers.

18. Questions?