Читать книгу Practical Power Plant Engineering - Zark Bedalov - Страница 32

A typical project passes through a number of development phases, starting from an initial estimate, conceptual design for feasibility study, detailed design, construction, and start up.

Let us name some typical projects:

 a power plant: hydro, diesel generation, gas combined cycle, etc., and

 an industrial project that may be an ore exploitation process, a factory of detergents, potato chips, and any other similar facility.

Utilities typically take care of the large power projects of this nature. They make a budget estimate of the project cost and evaluate it against the revenue based on the kWh to be sold to the consumers. The projected cost will include the initial capital for the equipment, materials, and labor over the years of construction, cost of money and plant maintenances, and operation (see Section 1.4.2)

The overall cost must include the transmission line from the power plant to the major switchyard. In case of a hydro project, the transmission lines are inevitably long and at higher transmission voltages. Diesel generation plants, on the other hand, are generally built for specific consumers in remote isolated areas. This may be a case of a mine up North needing 10–20 MW of power, for which the cost of building a transmission line would be rather prohibitive, in particular, if one evaluates it on the basis of the cost of km of line per MW delivered.

It is not only the utilities that are involved with power generation. There are small power producers called Independent Power Producers (IPPs) for generating anywhere from 2 to 100 MW. They generally do not get involved with power distribution and readily sell all the power to the local utilities.

The cost of fuel over the years of plant exploitation is always the most prevalent factor in the evaluation of a project development. This is where the hydro facility jumps ahead in spite of its huge cost of civil infrastructure. A gas fired plant will certainly be less costly on the basis of the initial cost of the plant and transmission line, but it is the cost of fuel per kWh produced that matters over the life of the plant. A diesel generation plant up North may be built at a low initial cost, but the cost of fuel is high, due to the additional cost of trucking and barging it to the site and storing it there for a full year. But do not forget that the usage of waste heat from the diesel engines can lift the plant efficiencies and reduce the cost of fuel usage.

An evaluation of a power plant also depends on the daily/weekly operating cycle. For hydro, the idea is to maximize the water usage, in particular during the rainy seasons to avoid spilling. Not many power hydro plants are built with a 100% operating capacity factor. A hydro project operating at 50% capacity factor is common, while I have seen hydro plants built for a projected 12% annual capacity factor. In other words, a plant of 100 MW installed capacity with a projected 12% capacity factor can produce, based on the estimated water availability, only 12 MW on a daily average for the whole year. It produces power when it has enough water drawing it down to the minimum operating level (MOL). Producing power below the MOL would be highly inefficient use of water resources and may make it difficult to recover back to the higher more efficient operating levels. Such plants with low capacity factors may be operating as base load generation during the rainy seasons and also as peaking plants because of their quick start capability when the marginal energy cost is the highest.

On the other hand, a fossil‐fuel operating plant costs a lot more to operate and is likely to be used for peaking duties in a daily cycle only. Therefore, the overall economics of building a fossil‐fuel operating plant in an area, which includes a mixture of different types of generation, must be estimated on the basis of its low operating hours.

While the power plant projects are built with the highest quality of equipment and redundancy, intended for 40 years of operation, an industrial plant may be built for a shorter duration of, say 10 years.

Levelized Cost Of Electricity (LCOE) is one of the yardsticks the owner's accountants use to compare the energy options for power plants. The formulae of totalizing the lifetime cost of production against the lifetime revenue are quite complex summations, using discount rates, inflation, and present worth accounting. Let the accountant work his figures. You as an engineer should understand the math behind it and offer technical options that may reduce the operating and initial costs to make the project more feasible.