sustainability: renewable energy strategies

SUSTAINABILITY | RENEWABLE ENERGY STRATEGIES
AN INTRODUCTION

Solar: Solar Thermal
Solar: Photo Voltaic
Solar: Chimney
Wind: Turbines / Generators
Hydropower
Co-generation
Bioenergy
Geothermal
Energy from Space
Hydrogen Energy / Fuel Cells

"Install a solar roof and during your lifetime you could prevent 34 tons of greenhouse gas emissions. Solar PV generated power could provide 10,000 times more energy than the world currently uses."- Solar Century

A patch of 100 square miles of open space covered with efficient solar panels such as in Nevada, where sun rays are powerful, could generate all the electrical power needs of the United States. - National Renewable Energy Laboratory

"We need to use available resources and technologies to make solar energy the backbone of the electricity network."
- Abdullah Juma

"Kyocera estimates that world demand (for Photovoltaics) will be 250MW per year by the year 2000, with 140MW in Japan." - Greenpeace report

The world market for solar cells has gone from $340 million in 1988 to $900 million in 1996. In Japan, housing companies have introduced homes with silicon roof tiles that generate enough electricity to meet most of a family's annual needs and have already installed 10,000." - Worldwatch

Solar Energy is Natural, Clean, and Reliable.
It reduces dependency on conventional fuels.

It protects you against inflationary fuel costs and possible shortages.

Solar equipment will pay for itself in fuel savings.

It will increase the resale value of your residential commercial, or industrial property.

The American Lung Association reports that air pollution from electricity production costs the nation $20 billion per year in health care impacts.

SUSTAINABILITY | Solar: Solar Thermal
Solar hot water heaters use the sun to heat either water or a heat-transfer fluid in collectors. A typical system will reduce the need for conventional water heating by about two-thirds. High-temperature solar water heaters can provide energy-efficient hot water and hot water heat for large commercial and industrial facilities.
Direct Systems: This system uses a pump to circulate potable water from the water storage tank through one or more collectors and back into the tank.
Indirect Systems: a heat exchanger heats a fluid that circulates in tubes through the water storage tank, transferring the heat from the fluid to the potable water.
Thermosiphons: has a tank mounted above the collector. As the collector heats the water, it rises to the storage tank, while heavier cold water sinks down to the collector.
Draindown Systems: In cold climates, this system prevents water from freezing in the collector by using electric valves that automatically drain the water from the collector when the temperature drops to freezing.
Swimming Pool Systems: In solar heated swimming pools, the pool's filter pump pumps water through a solar collector, and the pool itself stores the hot water.

SUSTAINABILITY | Solar: Photo Voltaic
Photovoltaic solar cells, which directly convert sunlight into electricity, are made of semiconducting materials. The simplest cells power watches and calculators and the like, while more complex systems can light houses and provide power to the electric grid.
Building-Integrated Photovoltaics (BIPV) these are double purpose of producing electricity and serving as construction materials. They can replace traditional building components, including curtain walls, skylights, atrium roofs, awnings, roof tiles and shingles, and windows.
Stand-Alone Photovoltaic System these produce power independently of the utility grid. In some off-the-grid locations as near as one-quarter mile from the power lines, stand-alone photovoltaic systems can be more cost-effective than extending power lines.

SUSTAINABILITY | Solar: 'Chimney'
The solar chimney basically operates like a hydroelectric power plant, but instead of water it uses hot air . These are designed primarily for desert location and consists of a tall column surrounded by a glass solar collector or greenhouse. The air is heated by a circular greenhouse and drawn through the chimney which acts as a thermal accelerator. Within the chimney are several vertical axis turbines.

SUSTAINABILITY | Solar: Thermal Concentrator
Concentrating solar power technologies use reflective materials such as mirrors to concentrate the sun's energy. This concentrated heat energy is then converted into electricity. There are three form of technologies:
Trough Collectors which areParabolic trough systems use curved mirrors to focus sunlight on an absorber tube filled with oil or other fluid. The hot oil boils water to produce steam, which is used to generate electricity;
Power Tower systems use a large field of sun-tracking mirrors, called heliostats, to concentrate sunlight onto a receiver on the top of a tower; Dish/Engine Systems, uses mirrors in the shape of a dish to collect and concentrate the sun's heat onto a receiver.

SUSTAINABILITY | Wind: Turbines / Generators
Wind turbines convert wind energy into electricity. The electricity
may be used in D/C or A/C form to supply equipment, lighting and other systems. Modern wind turbines are divided into two major categories: horizontal axis turbines and vertical axis turbines. Old-fashioned windmills are still seen in many rural areas.
Horizontal Axis Turbines (HAWT) are the most common turbine configuration used today. They consist of a tall tower, atop which sits a fan-like rotor that faces into or away from the wind, the generator, the controller, and other components.
Vertical Axis Turbines (VAWT) these fall into two major categories: Savonius (vertical blades) and Darrieus (S-shapedin plan)

SUSTAINABILITY | Hydropower
Flowing water creates energy that can be captured and turned into electricity. Hydropower is currently the largest source of renewable power, generating nearly 10% of the electricity used in the United States. The most common type of hydropower plant uses a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which, in turn, activates a generator to produce electricity. Another type of hydropower plant—called a pumped storage plant—can even store power. The power is sent from a power grid into the electric generators.

SUSTAINABILITY | Ocean
Ocean energy draws on the energy of ocean waves, tides, or on the thermal energy (heat) stored in the ocean.
Wave Energy: The total power of waves breaking on the world's coastlines is estimated at 2 to 3 million megawatts.
Tidal Energy: Tidal energy traditionally involves erecting a dam across the opening to a tidal basin electricity can be generated from the elevated water in the basin.
Ocean Thermal Energy Conversion (OTEC) Systems
A great amount of thermal energy (heat) is stored in the world's oceans. OTEC systems convert this thermal energy into electricity — often while producing desalinated water.

SUSTAINABILITY | Co-generation

Cogeneration is considered to be a very cost-efficient means of
generating both electricity and thermal energy [for cooling] from the same fuel source. The cost efficiency comes not only from the generation of electricity, which can be used to reduce the expense of purchased utility power, but also from the fact that the generated steam is used twice. A variety of fuel types may be used, ranging from natural gas to fuels such as wood or agricultural waste (refereed to as "bio-mass").

SUSTAINABILITY | Bioenergy
Bioenergy technologies use renewable biomass resources to produce an array of energy related products including electricity, liquid, solid, and gaseous fuels, heat, chemicals, and other materials.
Biomass Resources: The term "biomass" means any plant derived organic matter available on a renewable basis, including dedicated energy crops and trees, agricultural food and feed crops, agricultural crop wastes and residues, wood wastes and residues, aquatic plants, animal wastes, municipal wastes, and other waste materials.
Biopower: Biopower technologies are proven electricity generation options.. All of today's capacity is based on mature direct-combustion technology.
Biofuels: A variety of fuels can be made from biomass resources, including the liquid fuels ethanol, methanol, biodiesel, Fischer-Tropsch diesel, and gaseous fuels such as hydrogen and methane.
Biobased chemicals and materials: are commercial or industrial products, other than food and feed, derived from biomass feedstocks. Biobased products include green chemicals, renewable plastics, natural fibers, and natural structural materials.

SUSTAINABILITY | Geothermal Energy
Geo (Earth) thermal (heat) energy is an enormous, underused heat and power resource that is clean reliable (average system availability of 95%), and homegrown. Geothermal resources range from shallow ground to hot water and rock several miles below Earth's surface, and even farther down to the extremely high temperatures of molten rock called magma. Earth's energy can be converted into heat and electricity. The three technology categories are geothermal heat pumps, direct-use applications, and power plants.

SUSTAINABILITY | Geothermal Coupling / Heat Pumps
A geothermal heat pump is an electrically powered device that uses the natural heat storage ability of the earth and/or the groundwater to gain or lose heat. Concrete structure such as piles, foundations, etc., are used to absorb this energy from the ground and transported by means of fluid-filled pipes incorporated inside the foundations.

SUSTAINABILITY | Energy from Space
Opportunities in developing the ultimate source of power, are being researched and developed,and plans are being developed to build an orbiting power station to harvest solar energy and beam it to earth. A station would convert solar energy into micro waves and beam them down to Earth by means of an antenna.
In space applications, solar arrays work well for generating power in space and power virtually all satellites. Most satellites and spacecraft are equipped with crystalline silicon or high-efficiency Group III-IV cells, but recently satellites have begun using thin-film amorphous-silicon-based solar panels.

SUSTAINABILITY | Hydrogen Energy / Fuel Cells
This is widely seen as the fuel of the future, it is non-polluting, has a reasonable calorific value,and can be safely stored.Off-peak or PV electricity can be used to split water via an electrolyser to make hydrogen. This can be used as a direct fuel or to make electricity through the chemical reaction in a fuel cell.
Production: Hydrogen is produced from sources such as natural gas, coal, gasoline, methanol, or biomass through the application of heat; from bacteria or algae through photosynthesis; or by using electricity or sunlight to split water into hydrogen and oxygen.
Transport and Storage: The use of hydrogen as a fuel and energy carrier will require an infrastructure for safe and cost-effective hydrogen transport and storage.
Fuel Cells: Hydrogen's potential use in fuel and energy applications includes powering vehicles, running turbines or fuel cells to produce electricity, and generating heat and electricity for buildings. The current focus is on hydrogen's use in fuel cells.