Solar energy, requirements

The logistics requirements are quite different. Whereas biomass is optimally used when processed decentrally, the power density of solar energy requires processing at large centralized units. 

Now, consider stability. If a satisfactory initial system or component performance and cost are assumed, then in many cases the critical issue is to maintain the physical behavior of materials adjoining an interface for up to 30 years. The physical behavior may include properties that directly influence solar device performance, such as reflectance, transmittance, absorptance, emittance, and photovoltaic efficiency or solar device performance may be indirectly affected by properties such as adhesion, permeability, photo-oxidative stability, or interdiffusion. The required stability of interfaces in SECS components is counter to basic physics and chemistry, because atoms at interfaces must be more reactive and thermodynamically less stable than when in the bulk of materials (2). Yet, the density of solar energy requires deploying systems with large interfacial... 

The application of liquid-junction technology to photovoltaic power conversion is limited by problems associated with the semiconductor-electrolyte interface. Primary among these problems is corrosion. Efficient conversion of solar energy requires a band gap between 1.0 and 1.5 eV, and most semiconductors near this band gap corrode readily under illumination. Semiconductors with large band gaps (4-5 eV) tend to be more stable but cannot convert most of the solar spectrum. 

Field emissions from fertilization. Solar energy requirement. Electricity. 

Practice Problem A Calculate the solar energy required to produce 5255 g of C H Oj. 

Selenium is also used in thin-film photovoltaic cells (qv) which contain copper indium diselenide [12018-95-0] CuInSe2. Use is quite small as of 1996. However, if the United States solar energy output with such cells were to increase by 100 MW/yr, this would require 8 t of selenium aimuaHy (see... 

Brine Preparation. Rock salt and solar salt (see Chemicals frombrine) can be used for preparing sodium chloride solution for electrolysis. These salts contain Ca, Mg, and other impurities that must be removed prior to electrolysis. Otherwise these impurities are deposited on electrodes and increase the energy requirements. The raw brine can be treated by addition of sodium carbonate and hydroxide to reduce calcium and magnesium levels to below 10 ppm. If further reduction in hardness is required, an ion-exchange resin can be used. A typical brine specification for the Huron chlorate ceU design is given in Table 6. 

Radiative heat transfer is perhaps the most difficult of the heat transfer mechanisms to understand because so many factors influence this heat transfer mode. Radiative heat transfer does not require a medium through which the heat is transferred, unlike both conduction and convection. The most apparent example of radiative heat transfer is the solar energy we receive from the Sun. The sunlight comes to Earth across 150,000,000 km (93,000,000 miles) through the vacuum of space. FIcat transfer by radiation is also not a linear function of temperature, as are both conduction and convection. Radiative energy emission is proportional to the fourth power of the absolute temperature of a body, and radiative heat transfer occurs in proportion to the difference between the fourth power of the absolute temperatures of the two surfaces. In equation form, q/A is defined as ... 

Ocean thermal energy conversion (OTEC) power plants generate electricity by exploiting the difference in temperature between warm water at the ocean surface and colder waters found at ocean depths. To effectively capture this solar energy, a temperature difference of 35°F or more between surface waters and water at depths of up to 3,000 feet is required. This situation can be found in most of the tropical and subtropical oceans around the world that are in latitudes between 20 degrees north and 20 degrees south. 

The fact that solar energy is an intermittent energy resource means that energy storage systems (e.g., batteries, ultracapacitors, flywheels, and even hydrogen) will be required if solar energy is to be utilized widely. In addition, a variety of toxic chemicals are used in the manufacture of PV cells however, studies of the risks associated with their manufacture and disposal indicate little threat to surroundings and the environment. 

Solar energy offers a clean, sustainable alternative to continued use of fossil fuels. In its various forms it is already providing useful amounts of energy on a global basis, and will provide steadily increasing amounts in the twenty-first century, especially as developing countries require more energy to improve their economies. 

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