With solar cell power, it is also more efficient, because doesn’t need any fuel, so it requires almost no operating costs, cause the nature have giving it for free.

The installment could be applied in two ways, which are centralization can be applied (set in an area and the generated electricity distributed through a distribution network into places where it is needed) and decentralization (each stand-alone system / individual, does not require a distribution network).

And of course the impact for environment is zero pollution. Air pollution is a major problem in many cities, the biggest cause of urban air pollution is from burning of petroleum, including fuel used for transportation. With these solar cell technology at least it could reduce the amount of pollution.

Below are the advantages using solar cell power for public lighting:
- More Bright and durable
- Save energy without the cost of electricity
- Environmentally friendly with no pollution
- Quick and easy installation
- Maintenance Free
- The LED could hold for 3 years.

Therefore, gas turbines are mostly used for peak load production and for auxiliary power, such as during major plant outages. However, recently many natural gas-fueled gas turbine plants have been installed in the United States and other countries; but these usually employ the combined cycle mode, which has a higher efficiency than the single cycle mode.

Compressed air enters a combustion chamber, where liquid or gaseous fuel is injected. The combustion of the fuel increases the temperature of the combustion gas, producing a net work output of the turbine–compressor system. The temperature of the combustion gases is on the order of 1100–1200 ◦C, which is the maximum tolerable by present-day steel alloys used for gas turbine blades. Even at these temperatures, thermal stresses and corrosion problems are manifested, so that turbine blade cooling from the inside or outside of the blades by air or water is necessary.

Gas turbines are of the reaction type, where blades form a converging nozzle in which the combustion gases expand, thus converting enthalpy to kinetic energy. As in steam turbines, staged turbines are employed, consisting of several rows of moving and fixed blades.

The working fluid in gas turbines, composed of nitrogen, excess oxygen, water vapor, and carbon dioxide, is not recycled into the compressor and combustion chamber but is, instead, vented into the atmosphere. In some systems, a part of the energy still residing in the exhaust gas is recovered in heat exchangers to heat up the air entering the combustion chamber in order to enhance the overall thermal efficiency of the Brayton cycle, but eventually the exhaust gas is vented. This is in contrast to steam turbines where the working fluid, steam, is recycled into the boiler as condensed water.

Only in the twentieth century, with the advent of the steam turbine, and its requirement for large steam pressures and flows, has the water wall boiler been fully developed. In a modern water wall boiler the furnace and the various compartments of the boiler are fully integrated.

Water from the high pressure feed water heater at a temperature of 230–260 ◦C is further heated in the economizer section of the boiler to 315 ◦C, then flows into the steam drum, which is mounted on top of the boiler. The steam drum measures typically 30 m in length and 5 m in diameter. In the steam drum liquid water is separated from the steam, usually by gravity. From the steam drum, liquid water flows down the downcomer tubes into the header. From there, the hot pressurized water flows upward (because of a negative density gradient) through the riser tubes, where the actual boiling of water into steam occurs. The separated steam passes another section of the boiler, called the superheater, where its temperature is raised to 565 ◦C at a pressure of 24 MPa.

At this point the temperature and pressure are higher than the critical temperature (Tc = 374 ◦C) and pressure (pc = 22 MPa) of water. The supercritical steam drives the high-pressure turbine. The exhaust steam from the high-pressure turbine flows through the reheater section of the boiler, where the temperature is raised again to about 500 ◦C at a pressure of 3.7 MPa.

This steam drives the low-pressure turbine. The superheater and reheater sections of the boiler are usually situated past
a bend in the boiler, called the neck. In order to optimize thermal efficiency, the combustion air is preheated to a temperature of 250–350 ◦C in the air preheater section of the boiler. Near the burners, heat is transferred from the combustion gases to the boiler tubes by radiation. Away from the burners, heat is transferred mainly by convection. Coal and oil flames are highly luminous in the visible portion of the spectrum because of the radiation from unburnt carbon and ash particles.

Natural gas flames are less visible because of the absence of particles in the flame. However, most of the radiative transfer of heat from all flames occurs in the nonvisible infrared portion of the spectrum. The theoretical (Carnot) thermodynamic efficiency of a heat engine that works between a temperature differential of 838 K (565 ◦C) and 298 K (25 ◦C)—that is, between the temperature of the superheater and the condensation temperature of water in the condenser—is
η = (TH − TL)/TH = 64%.

However, as mentioned in the introduction, typical efficiencies of steam power plants are in the 33–40% range. Because heat is added to the water and steam at all temperatures between these limits, the Rankine cycle efficiency is necessarily lower than the Carnot value. Furthermore, parasitic efficiency degradation occurs because of heat losses through the walls of the boiler, ducts, turbine blades and housing, and frictional heat losses.

The coal particle or oil droplet burns from the outside to the core, leaving behind incombustible mineral matter. The mineral matter is called ash. In modern pulverized coal and atomized oil fired power plants, more than 90% of the mineral matter forms the so-called fly ash, which is blown out of the boiler by forced or natural draft and is later captured in particle collectors.

About 10% of the mineral matter falls to the bottom of the boiler as bottom ash. When the bottom of the boiler is filled with water, the bottom ash forms a wet sludge, which is sluiced away into an impoundment. Some of the fly ash, however, is deposited on the water pipes lining the boiler. This forms a slag which hinders heat transfer. The slag needs to be removed from time to time by blowing steam jets against it or by mechanical scraping.

Coal burns relatively slowly, oil burns faster, and gas burns the fastest. For complete combustion (carbon burn-out), excess air is delivered—that is, more air than is required by a stoichiometric balance of fuel and the oxygen content of air. Pulverized coal requires 15–20% excess air; oil and gas 5–10%.

The central coal impeller carries the pulverized coal from the silo in a stream of primary air. Tangential doors (registers) built into the wind box allow secondary air to be admixed, generating a fast burning turbulent flame. The impeller is prone to corrosion and degradation and has to be replaced once a year or so.

The burners are usually arranged to point nearly tangentially along the boiler walls. In such a fashion a single turbulent flame ensues from all four burners in a row, facilitating the rapid and complete burn-out of the fuel. Depending on the power output of the boiler, as many as six rows of burners are employed, totaling 24 burners.

Some power plants employ cyclone furnaces, especially for poorer grades of coal with a high ash content. In a cyclone furnace the combustion of the pulverized coal is accomplished in a watercooled horizontal cylinder located outside the main boiler wall. The hot combustion gases are conveyed from the cyclone furnace to the main boiler.

The advantage of a cyclone burner is that the majority of the mineral matter forms a molten ash, called slag, which is drained into the bottom of the boiler, and only a smaller portion exits the boiler as fly ash. Thus, smaller and less expensive particle collectors are required. The disadvantage is that at the high temperatures experienced inside the cyclone furnace, copious quantities ofNOxare formed. Nowadays, plants equipped with cyclone furnaces require the installation of flue gas denitrification devices for reducing NOx concentrations in the flue gas, largely vitiating the cost savings of cyclone furnaces in terms of coal quality and ash content.

Some older power plants and smaller industrial boilers employ stoker firing. In stoker-fired boilers, the crushed coal is introduced into the boiler on an inclined, traveling grate. Primary air is blown from beneath the grate, and secondary overfire air is blown above the grate. By the time the grate traverses the boiler, the coal particles are burnt out, and the ash left behind falls into a hopper.

The carbon burn-out efficiency is lower in stoker than in pulverized coal burners because of poorer mixing of coal and air that is achievable in stoker-fired boilers. Therefore, stoker-type boilers have a lower thermal efficiency compared to pulverized coal boilers.

The major components of a fossil fueled power plant are as follows:
• Fuel storage and preparation
• Burner
• Boiler
• Steam turbine
• Gas turbine
• Condenser
• Cooling tower
• Generator
• Emission control

Fuel Storage and Preparation
Coal is delivered to a power plant by rail or, in the case of coastal or riverine plants, by ship or barge. Usually, power plant operators like to have several weeks of coal supply on site, in case of delivery problems or coal mine strikes. Because a 1000-MW power plant, having a thermal efficiency of 35%, consumes on the order of 1E(4) metric tons of coal per day, the coal mounds near the plant may contain up to 3E(5) metric tons of coal. Some coal-fired power plants are situated right near coal mines (so-called mine-mouth plants). Even these plants store at least a month’s supply of coal
near the plant.

When coal arrives by rail, it is usually carried by a unit train, consisting of a hundred wagons filled with coal, at 100 tons per wagon. The wagons are emptied by a rotary dump, and the coal is carried by conveyors to a stockpile, or directly to the power plant.

Coal is delivered to a plant already sized to meet the feed size of the pulverizing mill, in the order of a few to ten centimeters per coal lump. In the United States and many other countries, coal is washed at the mine.Washing of coal removes much of the mineral content of the coal (including pyritic sulfur), thus reducing its ash and sulfur content and improving its heating value per unit mass. In preparation for washing, the coal is crushed at the mine mouth to less than
a centimeter per nut or slack.

Most modern steam power plants fire pulverized coal. The raw coal from the stockpile is delivered on a conveyor belt directly to a pulverizing mill. Such mills are either of the rotating ring, rotating hammer, or rotating ball type. The mill reduces the raw coal lumps to particles smaller than 1 millimeter. The pulverized coal is stored in large vertical silos from whence it is blown pneumatically into the burners at a rate demanded by the load of the plant.

In oil-fired power plants, oil is stored in large tanks (the “tank farm”), to which oil is delivered either by pipeline, by railroad tankers, or by tanker ship or barge if the plant is located near navigable waters. Power plants like to have at least a 30-day supply of oil in their tanks. For a 1000-MW plant with 35% efficiency, this can amount to over 1E(5) metric tons of oil. The oil is purchased from refineries in the form it is combusted in the burners, with specified sulfur, nitrogen, and ash
content as well as other properties, such as viscosity and vapor pressure.

In natural gas-fired power plants, gas is delivered to the power plant by pipeline at high pressure (compressed natural gas, CNG). Some gas-fired power plants use liquefied natural gas (LNG). Liquefied gas is transported in huge (up to 1.25E(5) m3) refrigerated tankers at −164 ◦C. The LNG is stored in refrigerated tanks until used.