-Engineering- (Ebook - Pdf) Crc Press - Wind And Solar Power Systems (Patel @1999).pdf - wiatraki - j_czaja1

Introduction

1.1 Industry Overview

and over 90 quadrillion BTUs in the United States

of America, distributed in segments shown in Figure 1-1 . About 40 percent

of the total primary energy is used in generating electricity. Nearly 70 percent

of the energy used in our homes and ofﬁces is in the form of electricity. To

meet this demand, 700 GW of electrical generating capacity is now installed

in the U.S.A. For most of this century, the U.S. electric demand has increased

with the gross national product (GNP). At that rate, the U.S. will need to

install additional 200 GW capacity by the year 2010.

The new capacity installation decisions today are becoming complicated

in many parts of the world because of difﬁculty in ﬁnding sites for new

generation and transmission facilities of any kind. In the U.S.A., no nuclear

power plants have been ordered since 1978

BTUs worldwide

( Figure 1-2 ) . Given the potential

for cost overruns, safety related design changes during the construction, and

local opposition to new plants, most utility executives suggest that none will

be ordered in the foreseeable future. Assuming that no new nuclear plants

are built, and that the existing plants are not relicensed at the expiration of

their 40-year terms, the nuclear power output is expected to decline sharply

after 2010. This decline must be replaced by other means. With gas prices

expected to rise in the long run, utilities are projected to turn increasingly

to coal for base load-power generation. The U.S.A. has enormous reserves

of coal, equivalent to more than 250 years of use at current level. However,

that will need clean coal burning technologies that are fully acceptable to

the public.

An alternative to the nuclear and fossil fuel power is renewable energy

technologies (hydro, wind, solar, biomass, geothermal, and ocean). Large-

scale hydroelectric projects have become increasingly difﬁcult to carry

through in recent years because of competing use of land and water. Reli-

censing requirements of existing hydro plants may even lead to removal of

some dams to protect or restore wildlife habitats. Among the other renewable

The total annual primary energy consumption in 1997 was 390 quadrillion

(10

15)

FIGURE 1-1

Primary energy consumption in the U.S.A. in three major sectors, total 90 quadrillion BTUs in

1997. (From U.S. Department of Energy, Ofﬁce of the Integrated Analysis and Forecasting,

Report No. DE-97005344, April 1997.)

FIGURE 1-2

The stagnant nuclear power capacity worldwide. (From Felix, F., State of the nuclear economy,

power sources, wind and solar have recently experienced a rapid growth

around the world. Having wide geographical spread, they can be generated

near the load centers, thus simultaneously eliminating the need of high

voltage transmission lines running through rural and urban landscapes.

The present status and beneﬁts of the renewable power sources are com-

pared with the conventional ones in Tables 1-1 and 1-2 , respectively.

The renewables compare well with the conventionals in economy. Many

energy scientists and economists believe that the renewables would get much

more federal and state incentives if their social beneﬁts were given full credit.

TABLE 1-1

Status of Conventional and Renewable Power Sources

Conventional

Renewables

Coal, nuclear, oil, and natural gas

Wind, solar, biomass geothermal, and ocean

Fully matured technologies

Rapidly developing technologies

Numerous tax and investment subsidies

embedded in national economies

Some tax credits and grants available from some

federal and/or state governments

Accepted in society under the ‘grandfather

clause’ as necessary evil

Being accepted on its own merit, even with

limited valuation of their environmental and

other social beneﬁts

TABLE 1-2

Beneﬁts of Using Renewable Electricity

Traditional Beneﬁts

Nontraditional Beneﬁts

Per Million kWh consumed

Monetary value of kWh consumed

U.S. average 12 cents/kWh

U.K. average 7.5 pence/kWh

Reduction in emission

750–1000 tons of CO

7.5–10 tons of SO

3–5 tons of NOx

50,000 kWh reduction in energy loss in power lines and

equipment

Life extension of utility power distribution equipment

Lower capital cost as lower capacity equipment can be

used (such as transformer capacity reduction of 50 kW

per MW installed)

, and NOx, and

the value of not building long high voltage transmission lines through rural

and urban areas are not adequately reﬂected in the present evaluation of the

renewables.

, SO

1.2 Incentives for Renewables

A great deal of renewable energy development in the U.S.A. occurred in the

1980s, and the prime stimulus for it was the passage in 1978 of the Public

Utility Regulatory Policies Act (PURPA). It created a class of nonutility power

generators known as the “qualiﬁed facilities (QFs)”. The QFs were deﬁned

to be small power generators utilizing renewable energy sources and/or

cogeneration systems utilizing waste energy. For the ﬁrst time, PURPA

required electric utilities to interconnect with QFs and to purchase QFs’

power generation at “avoided cost”, which the utility would have incurred

by generating that power by itself. PURPA also exempted QFs from certain

For example, the value of not generating one ton of CO

federal and state utility regulations. Furthermore, signiﬁcant federal invest-

ment tax credit, research and development tax credit, and energy tax credit,

liberally available up to the mid 1980s, created a wind rush in California,

the state that also gave liberal state tax incentives. As of now, the ﬁnancial

incentives in the U.S.A. are reduced, but are still available under the Energy

Policy Act of 1992, such as the energy tax credit of 1.5 cents per kWh. The

potential impact of the 1992 act on renewable power producers is reviewed

in Chapter 16.

Globally, many countries offer incentives and guaranteed price for the

renewable power. Under such incentives, the growth rate of the wind power

in Germany and India has been phenomenal.

1.3 Utility Perspective

Until the late 1980s, the interest in the renewables was conﬁned primarily

among private investors. However, as the considerations of fuel diversity,

environmental concerns and market uncertainties are becoming important

factors into today’s electric utility resource planning, renewable energy tech-

nologies are beginning to ﬁnd their place in the utility resource portfolio.

Wind and solar power, in particular, have the following advantages to the

electric utilities:

• Both are highly modular in that their capacity can be increased

incrementally to match with gradual load growth.

• Their construction lead time is signiﬁcantly shorter than those of the

conventional plants, thus reducing the ﬁnancial and regulatory risks.

• They bring diverse fuel sources that are free of cost and free of

pollution.

Because of these beneﬁts, many utilities and regulatory bodies are increas-

ingly interested in acquiring hands on experience with renewable energy

technologies in order to plan effectively for the future. The above beneﬁts

are discussed below in further details.

1.3.1 Modularity

The electricity demand in the U.S.A. grew at 6 to 7 percent until the late

1970s, tapering to just 2 percent in the 1990s as shown in Figure 1-3 .

The 7 percent growth rate of the 1970s meant doubling the electrical energy

demand and the installed capacity every 10 years. The decline in the growth

rate since then has come partly from the improved efﬁciency in electricity

utilization through programs funded by the U.S. Department of Energy. The

small growth rate of the 1990s is expected to continue well into the next century.

FIGURE 1-3

Growth of electricity demand in the U.S.A. (Source: U.S. Department of Energy and Electric

Power Research Institute)

The economic size of the conventional power plant has been 500 MW to

1,000 MW capacity. These sizes could be justiﬁed in the past, as the entire

power plant of that size, once built, would be fully loaded in just a few years.

At a 2 percent growth rate, however, it could take decades before a 500 MW

plant could be fully loaded after it is commissioned in service. Utilities are

unwilling to take such long-term risks in making investment decisions. This

has created a strong need of modularity in today’s power generation industry.

Both the wind and the solar photovoltaic power are highly modular. They

allow installations in stages as needed without losing the economy of size

in the ﬁrst installation. The photovoltaic (pv) is even more modular than the

wind. It can be sized to any capacity, as the solar arrays are priced directly

by the peak generating capacity in watts, and indirectly by square foot. The

wind power is modular within the granularity of the turbine size. Standard

wind turbines come in different sizes ranging from tens of kW to hundreds

of kW. Prototypes of a few MW wind turbines are also tested and are being

made commercially available in Europe. For utility scale installations, stan-

dard wind turbines in the recent past have been around 300 kW, but is now

in the 500-1,000 kW range. A large plant consists of the required number

and size of wind turbines for the initially needed capacity. More towers are

added as needed in the future with no loss of economy.

For small grids, the modularity of the pv and wind systems is even more

important. Increasing demand may be more economically added in smaller

increments of the green power capacity. Expanding or building a new con-

ventional power plant in such cases may be neither economical nor free from

the market risk. Even when a small grid is linked by transmission line to

the main network, installing a wind or pv plant to serve growing demand

may be preferable to laying another transmission line. Local renewable

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