Solar energy desalination is a method by which the sun’s energy is used to desalinate brackish or seawater to produce fresh drinkable water. There are two methods for using solar energy: directly by heating and evaporating the brackish or seawater in a solar still (this method is called solar distillation) and indirectly by capturing solar energy using one of the techniques that transform solar radiation into thermal or electrical energy to drive a conventional desalination method (the indirect method is called solar-assisted or solar-driven desalination). (more…)

Drying is one of the most important post harvest steps. It enhances the storage life of the crop products, minimizes losses during storage, and saves shipping costs. The drying process is the removal of water from the wet surface of the food. In this process, heat is transferred by convection and radiation to the surface of the produce. This heat raises the temperatures heat and evaporates the moisture from the exterior of the agricultural products, diffusing the interior moisture to the surface and replenishing the evaporated surface moisture. (more…)

Solar distillation is the process in which solar heat is used to purify water from an impure water source by evaporation and condensation. When solar distillation is used to purify water from saline water, the process is also called solar desalination. Desalination converts saline water with high salt content, about 3.5% by weight in seawater and about 0.6% in brackish water, into fresh water suitable for drinking and other purposes. Use solar energy can be used for desalination, either as thermal energy through the use of solar thermal collectors or solar ponds, or as electricity. mainly through the use of photovoltaic cells. (more…)

Biomass Storage

Biomass storage is required to ensure the continuous operation of the facility. To limit the space required for storage at the plant site, biomass must be stored in relatively high piles. Two main problems associated with fuel storage are decomposition and selfheating. Self-heating increases the rate of decomposition and fire risk, and it encourages the growth of thermophilic fungi whose spores can cause a respiratory condition in humans similar to farmers lung. Some small virgin biomass losses may occur at the storage stage, but they are likely to be negligible. For intermediary storage of the fuel between the pretreatment (e.g., drying and sizing) and gasification stage, storage silos may be used. (more…)

The moisture content of the feedstock affects the gas composition and the energy balance of the process since gasification is an endothermic process. Water vapor, however, is an essential component of gasification reactions. Therefore, there is a trade-off between the extent of fuel drying and the quality of product gas. Drying of the feedstock to a moisture content of approximately 15% is commonly adopted. Fuel drying is likely to be the most energy intensive activity in the biomass gasification process. Important contributions can be made to the energy balance by using flue gases or steam to dry the biomass. The heat used for drying does not have to be high temperature, and a low temperature level is actually desired because it will prevent the evaporation of undesirable organic components. (more…)

The demand for electric energy by a community varies with the time of day and with the time of year. An electric power utility must be prepared to meet these demands. This poses an engineering problem because there is no practical method of storing electric energy on a scale that will meet the demands of a large community. To meet short-term increases in demand, electric utilities employ power generators that can be turned on and off on short notice. For example, they may use a gas turbine similar to a jet plane engine to drive a generator. Another scheme is to use a pumped storage hydroelectric system. Such a system does not rely on nature to replenish the water in a reservoir but rather uses electrically run pumps. Importantly, the system can generate electricity on short notice.

Water is forced to an elevated reservoir by a motor-driven turbine. The water in the reservoir has gravitational potential energy by virtue of the work done on it. When electricity is needed, the water is allowed to flow downward into the turbine that drives the magnetic generator motor, which now functions as an electric generator. The energy required to elevate the water is never completely recovered in the process. Nevertheless, the system is economical because the reservoir can be filled when electric energy demands and costs are low. It is also possible to have a system in which water flows from ground level to underground turboelectric perpetual generators. In this case, work has to be done to restore the water to ground level.

Taking into account losses due to evaporation of surface water exposure and energy unit conversion losses, it is estimates that approximately 70% to 85% of the electricity used to pump water into the elevated reservoir can be recovered. The technique is currently the most effective way to store large quantities of electrical energy in the form of energy operation, but the cost of capital and the presence of appropriate geography critical factors for the decision.

With energy management, well to pump storage hydroelectric systems for controlling the frequency of food production and security of reserve magnetic power generator. Thermal plants are much less able to responds in the sudden changes in electricity demand, the frequency and voltage to cause instability. Pumping stations, like other water plants can respond to changes within seconds to load with pumped storage hydroelectric system.

Polymer Electrolyte Fuel Cells have high-power density, rapid startup, and low-temperature operation (around 80 to 120 C), and so are ideal for use in applications such as energy transport and battery replacement. The electrolyte used is a proton conducting polymer. This is typically a perfluorinated polymer, though other hydrocarbon-based membranes are under development in an attempt to reduce cost or to enable operation at temperatures approaching 200 C. The catalytically active layer sits adjacent to the membrane, supported on a PTFE treated carbon paper, which acts as current collector and gas diffusion layer. For operation on pure hydrogen, platinum is the most active catalyst, but alloys of platinum and ruthenium are used when higher levels of carbon monoxide are present (CO is a poison in all low temperature fuel cells). (more…)

The fuel cycle for a given transportation fuel includes the following processes: energy feedstock (or primary energy) production; biomass feedstock transportation and storage; fuel production; fuel transportation, storage, and distribution; and vehicle operations that involve fuel combustion air or other chemical energy conversions. The processes that precede vehicle operations are often referred to as the well-to-pump (WTP) stage, the vehicle operations are referred to as the pump-to-wheels (PTW) stage, and the entire fuel cycle is referred to as the well-to-wheels (WTW) cycle. Various models have been developed that allow researchers to conduct fuel cycle analyses of vehicle/fuel systems. The GREET (greenhouse gases, regulated emissions, and energy transportation) model, developed by Argonne National Laboratory, is in the public domain and, so far, more than 1000 users worldwide have used the model to predict the energy use and emissions associated with alternative fuels vehicles. The GREET model and its documents are posted on the Internet at http:// greet.anl.gov. (more…)

Several passive heating systems, if provided with proper ventilation, can ensure to provide cooling. Passive heating and cooling for houses can be done in several ways, one of which is called geothermal energy. Passing the water through pipelines via ground can achieve and distribute the heating and cooling all over the house. (more…)

In the mid-1880s, Charles Fritts built the first solar cell formed by selenium coated with a thin layer of gold and with an energy efficiency of 1%. However, it was not until 1954 that Bell Labs discovered accidentally that would be the first commercial solar cell, with silicon as the base. (more…)