Renewable Energy Opportunities and Challenges

1. Renewable Energy Opportunities and Challenges Phil Malte Professor of Mechanical Engineering September 22, 2006

2. US Renewable Energy Use2004: 6.1 quads, 6.1% of primary energy use.Predominant: hydroelectric and wood wasted burned in the wood products and pulp/paper industries.Renewable energy in last place: behind the 3 major fossil energies and now also behind nuclear.

3. Worldwide Renewable Energy Use 2003: 27 quads of hydroelectric,which is about 6% of total worldwide commercial primary energy use (420 quads).Worldwide biomass use is estimated to add about 50 quads – a significant amount of this use occurs in developing nations.Percentage-wise (and absolute-wise), the world uses considerably more renewable energy than the US.

4. Direct Solar Solar water heating Solar thermal electric Solar PV Passive heating Indirect Solar Motion of water Hydro-electric Wave energy Ocean streams Wind Indirect Solar Cont. Biomass Direct combustion Gasification Fermentation Anaerobic digestion Biofuels Non-Solar Geothermal Tidal Barrage Current Renewable Energies

5. Capacity (rated power generation) 12/04

6. Terms • Capacity = Rated Power Output • Efficiency = Power Out / Power In • Capacity Factor: Average Power Output / Rated Power Output • Most renewable energy systems: CF = 0.1 to 0.5 • Fossil fuel and nuclear power plants: CF = 0.8 to 0.9 • Rated power can be misleading, ask about the average power

7. Mature. Long history. Evolved from water wheels for grinding. US development: 1930-60 Worldwide resource: 2300 GW. 650 GW installed capacity. Most of the resource of Asia (20%), South America (20%), and Africa (5%) undeveloped. North American resource is about 50%-developed. About 90% of European resource developed. Columbia/Snake: 23 GW installed capacity, 19 dams. Environmental impact to rivers and streams, land flooded, and to fish killed. Large hydro turbines: 70 to 98% fish survivability, 95-98% bypass. Purposes: electricity generation, flood control, and irrigation. Power of water = rghQ Power (watts) = P Density = r = 1000kg/m3 Head (meters) = h Flow rate (m3/s) = Q Hydro Plant Output P = rghQh Efficiency (h) accounts for: Friction in penstock Friction in turbine Hydrodynamic efficiency of turbine Efficiency of generator Typically h = 60-80%. Typically CF = 40-50% Hydro-electric

8. Grand Coulee Hydropower

9. Washington State Facilities

10. Washington State Energy Use (2001) Energy Use (Trillion BTU) Oil Hydro Natural Gas Coal Nuclear Wood Waste

11. Tidal Barrage (Brittany Coast of France)

12. Tidal Current(Devices under RD&D)

13. High current regions of estuaries and rivers Tidal current predictable UK leader in RD&D 10-100 MW power plants appear feasible EPRI feasibility study published this summer First US demo: East River Puget Sound potential being assessed In-Steam Turbines

14. 4 Examples of Wave Energy Devices (RD&D) Attenuator Point Absorber Oscillating Water Column Overtopping

15. Several devices invented. The device shown, 100-150 meters long, bends as it rides the waves, causing rods inside to move, driving electric generators. UK RD&D. Wave-tidal test center north of Scotland. OSU has wave energy research center. Oregon coast has the infrastructure for using the electricity – this is lacking on WA coast EPRI study last year. Wave Energy Machines

16. Wind Turbines

17. Established technology Long history – wind mills for grinding, farm turbines for water pumping. Electrical generation turbines since 1920s. Significant US RD&D in 1970s. Europe became the manufacturing leader in 1990s. Annual rate of growth about 20%. Installed capital cost about $1000/kw P (average) rVa3Ah Large 2-3 bladed turbine efficiency: 40-50%. Capacity factor: 0.3-0.4. Capacity by country: World (48 GW) Germany (16.7 GW) Spain (8.3 GW) US (6.8 GW) Denmark (3.1 GW) India (3.0 GW) Installed in 2004 (8.2 GW): Spain (2.1 GW) Germany (2.1 GW) India (0.9 GW) US (0.4 GW) Leading manufacturers: Vestas (DK, 34%) Gamesa (ES, 17%) Enercon (DE, 15%) GE Wind (US, 11%) Siemens (DE, 6%) Wind Turbines

18. http://rredc.nrel.gov

19. Trends and Challenges • Suitable wind turbine sites tend to be located distant from urban centers. Thus, the need for and cost of new electrical transmission can be a challenge. • Off and on production tax credit in US has been a challenge. • Off shore wind turbines, especially in Europe, may be the next major development. • Variable speed wind turbines now available, replacing constant speed technology. • Gear box, generator, and power conditioning offer opportunities for system improvement. • The randomness and unpredictability of the winds present a challenge for integrating wind power into the power system. • Energy storage methodology and experience lacking. • Wind turbine site selection and installation can be controversial and can encounter strong resistance.

20. Energy from Biomass: PNW • The energy consumed from biomass in WA State is essentially as much as that from coal or nuclear. • Most of the WA (and OR and ID) biomass energy use is associated with the wood products and pulp/paper industries. • Combustion of bark for mill steam and heat. • Combustion of wood product trimmings, sawdust and sanderdust for mill steam and heat. • Combustion of black liquor, a product of chemical wood pulping. Black liquid is composed of the spent pulping chemicals (Na and S) and the lignin (not cellulosic) fraction of the wood. Burning the black liquor in recovery furnaces captures the pulping chemicals for reuse and liberates the heating value of the lignin for steam generation needed by the mill. • Additionally, though of secondary use, wood is burned for residential space heating in WA, OR, ID and elsewhere in the US.

21. Energy from Biomass (Europe) • This picture also holds for the forested areas of northern Europe, though a better use of the biomass resource for co-generation is practiced in Sweden and Finland, and the combustion and fuel upgrading technologies tend to be superior to those used elsewhere. • Some of the large-scale European systems use fluidized bed combustors and gasifiers. In the case of the gasifiers, the biomass is converted into a syngas of H2, CO, H2O, and CO2, which is burned in the furnace/boiler for heat and power. • Integrated gasification combined cycle (biomass IGCC) systems, in which the syngas is burned in a gas turbine engine, have not been proven commercially viable.

22. Energy from Biomass (Developing World) • Large amounts of biomass are used for cooking and heating in rural sections of the developing world. This is the greatest energy use of biomass in the world. The fuel sources are: • Wood gathered • Animal dung • Crop residues • In most cases, the heating value of these fuels is converted to heat by direct combustion. Typically, the particulate emission (ie, smoke) is very high. • Improvements include: • Gasification of the fuel to gas which is burned. These are simple, small-scale, air-blown gasifiers. These are cleaner and more efficient than direct combustion. • Anaerobic digestion of animal and crop wastes to methane, which is burned for cooking. • Large-scale combustion of biomass is also practiced in the developing world, for example: combustion of bagasse for power generation and heat. • Throughout the world, methane (actually a CH4/CO2 product gas) is produced by anaerobic digestion in landfills and sewage sludge tanks and then cleaned for use to recip engines for power and heat generation.

23. Biofuels

24. Alternative Fuels for Vehicles in USMTBE and most of the US ethanol are oxygenate additives for gasolineLNG (liquified nat gas) use is small compared to CNG (compressed nat gas)Brazil’s production/use of ethanol also is plotted

25. Percentage of ethanol to oil use on energy basis for US and Brazil

26. Energy Ratio • Energy content of the fuel / Commercial energy input required to produce the fuel • Gasoline and diesel: Energy ratio  5 • Factors for biofuels: • Energy for farm machinery • Energy for chemical fertilizers • Energy for converting harvested biomass into biofuel • Use of agricultural residues for energy • Co-products • Corn ethanol: Energy ratio = 1.3-1.7 • Biodiesel: Energy ratio  3 (literature shows ERs from less than 1 to 4, depending on fertilizer use and credit from co-products) • Anhydrous ethanol (blended fuel) and hydrous ethanol (100% substitute for gasoline). Brazil offers E25 and E95 (hydrous ethanol), made from sugar cane.

27. Direct Solar – Solar Thermal for Hot WaterSeveral roof top residential domestic water heaters (composed of one or two collectors) are commercially available, including systems not requiring a mechanical pump (Australia) and systems using tubular collectors (based on the heat pipe principle, China). Worldwide, 40 million households use solar hot water. China generates over 50% of the world’s solar hot water. Scandinavia and Germany have built several large solar water heating systems for space heating. Two in Denmark are shown blow: a diurnal system on the left, and a seasonal system on the right – which stores the heat from summer to winter.

28. Direct Solar – Solar Thermal ElectricThere are three methods of solar thermal electric generation. These include the parabolic trough collector in which a fluid at the line focus is heated to about 400 C. This heat is then transferred to water/steam in the boiler of a Rankine cycle power plant. The picture at the left shows the 0.35 GW system at Kramer Junction, CA. The power tower, see picture at right, is another method. This involves point focus, leading to very high temperature. Typically. these systems are 10-20 MW. The other system, not shown below, is the point focus dish collector, typically of 25 kw capacity. This focuses the sunlight onto the hot end of a Stirling engine driving an electrical generator.

29. Direct Solar: Passive Solar Heating of the Built Environment • Solar energy consumption statistics normally do not include passive solar. • Passive solar involves the heating of homes and buildings by solar energy entering through windows and skylights. For a typical home in the UK, this represents about 15% of the heating requirement of the home over the year, with the contribution coming mainly in the autumn and spring, when heating of the home is required and adequate solar energy is available. In the winter, much like Seattle, little solar energy is available to meet the heating requirement, and in the summer, the solar energy typically is not needed (in fact, steps may be taken the shade the home from solar input). • Passive solar heating of homes is especially effective for areas such as the Rocky Mt states that have cold, sunny winters. Building design methods are well known and available for both enhancing the wintertime solar gain of homes and buildings and reducing their heat losses. • Methods are also well known and available for reducing the summertime solar gain of a building and for providing passive cooling and ventilation. • Mechanical cooling using solar energy is also known – solar absorption refrigeration. Non-solar methods involve the use of the coolness of the ground.

30. Direct Solar: Solar Photovoltaic (PV) (Grid Tied, UW Mech Engr Bldg) PV Panels on roof and wall produce DC power Inverters convert DC to AC power AC Power is sent to the electric grid

31. Direct energy conversion Typical efficiency: 10-20%. Worldwide installed capacity: 4000 MW (Japan > Europe > US  rest of world) Worldwide production in 2004: 1195 MW (57% growth relative to 2003) Installed cost (grid tied, US): $8/wpeak Worldwide applications Installed in 2004: Grid tied (610 MW) Off-grid (175) Communications (80 MW) Consumer Products (70 MW) Central Power Gen >100 kw (20 MW) Type of PV produced in 2004: Single Crystal Si: 340 MW Polycrystalline Si: 670 MW Other Si: 110 MW Other materials: 75 MW Manufacturers (2004 production) : Sharp (324 MW) Kyocera (105 MW) BP Solar (85 MW) Mitsubishi (75 MW) Q-Cells (75 MW) Shell Solar (72 MW) Sanyo (65 MW) Schott (65 MW) Isfoton (53 MW) GE Solar (25 MW) Solar PV Status

32. Solar PV Efficiency Trends, NREL Data