THREE
results that had been verified in this passage.
A
B
C
D
E
F
Non-identical twins come from different eggs.
Genetic relation between identical twins is closer than non-identical ones.
Vitamin C has an evident effect on a cold.
Genetic influence on smoking is superior to the environment’s
If a pregnant woman eats too much sweet would lead to skin disease.
Hair loss has been found to be connected with a skin problem.
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READING PASSAGE 3
You should spend about 20 minutes on Questions 28-40
Questions 28-40, which are based on Reading Passage
3 below.
Photovoltaics on the rooftop
Photovoltaics on the rooftop
A natural choice for powering the family home
A
In the past, urban homeowners have not always had much choice in the way electricity is
supplied to their homes. Now, however, there is a choice, and a rapidly increasing number of
households worldwide are choosing the solar energy option. Solar energy, the conversion of
sunlight into energy, is made possible through the use of ‘photovoltaics’, which are simple
appliances that fit onto the roof of a house.
B
The photovoltaics-powered home remains connected to the power lines, but no storage is
required on-site, only a box of electronics (the inverter) to the interface between the
photovoltaics and the grid network. Figure 1 illustrates the system. During the day, when the
home may not be using much electricity, excess power from the solar array is fed back to the
grid, to factories and offices that need daytime power. At night, power flows the opposite way.
The grid network effectively provides storage. If the demand for electricity is well matched to
when the sun shines, solar energy is especially valuable. This occurs in places like California in
the US and Japan, where air-conditioning loads for offices and factories are large but heating
loads for homes are small.
C
The first systematic exploration of the use of photovoltaics on homes began in the US during
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the 1970s. A well-conceived program started with the sitting of a number of residential
experiment stations’ at selected locations around the country, representing different climatic
zones. These stations contained a number of ‘dummy’ houses, each with different solar-energy
system design. Homes within the communities close to these stations were monitored to see
how well their energy use matched the energy generated by the stations’ dummy roofs. A
change in US government priorities in the early 1980s halted this program.
D
With the US effort dropping away, the Japanese Sunshine Project came to the fore. A large
residential test station was installed on Rokko Island beginning in 1986. This installation
consists of 18 ‘dummy’ homes. Each equipped with its own 2-5 kilowatt photovoltaic system
(about 20 – 50 square meters for each system). Some of these simulated homes have their own
electrical appliances inside, such as TV sets, refrigerators and air conditioning units, which
switch on and off under computer control providing a lavish lifestyle for the non-existent
occupants. For the other systems, electronics simulate these household loads. This test station
has allowed being explored in a systematic way, under well-controlled test conditions. With no
insurmountable problems identified, the Japanese have used the experience gained from this
station to begin their own massive residential photovoltaics campaign.
E
Meanwhile, Germany began a very important ‘1,000 roof program’ in 1990, aimed at installing
photovoltaics on the roofs of 1,000 private homes. Large federal and regional government
subsidies were involved, accounting in most cases for 70% of the total system costs. The
program proved immensely popular, forcing its extension to over 2,000 homes scattered across
Germany. The success of this program stimulated other European countries to launch a similar
program.
F
Japan’s ‘one million roof program’ was prompted by the experience gained in the Rokko Island
test site and the success of the German 1,000 roof program. The initially quoted aims of the
Japanese New Energy Development Organization were to have 70,000 homes equipped with
the photovoltaics by the year 2000, on the way to 1 million by 2010. The program made a
modest start in 1994 when 539 systems were installed with a government subsidy of 50
percent. Under this program, entire new suburban developments are using photovoltaics.
G
This is good news, not only for the photovoltaic industry but for everyone concerned with the
environment. The use of fossil fuels to generate electricity is not only costly in financial terms,
but also in terms of environmental damage. Gases produced by the burning of fossil fuels in the
production of electricity are a major contributor to the greenhouse effect. To deal with this
problem, many governments are now proposing stringent targets on the amount of
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greenhouse gas emissions permitted. These targets mean that all sources of greenhouse gas
emissions including residential electricity use will receive closer attention in the future.
H
It is likely that in the future, governments will develop building codes that attempt to constrain
the energy demands of new housing. For example, the use of photovoltaics or the equivalent
may be stipulated to lessen demands on the grid network and hence reduce fossil fuel
emissions. Approvals for building renovations may also be conditional upon taking such
energy-saving measures. If this were to happen, everyone would benefit. Although there is an
initial cost in attaching the system to the rooftop, the householder’s outlay is soon
compensated with the savings on energy bills. In addition, everyone living on the planet stands
to gain from the more benign environmental impact.
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