Engineers in Society (EE3014)Lecture Series

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Renewable Energy

Professor Y.C. ChanCity University of Hong KongDirector, EPA Centre

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Renewable Energy:-“Renewable Energy is energy that is derived from natural processes that

are replenished constantly. In its various forms, it derives directly or indirectly from the sun, or from heat generated deep within the earth”

- International Energy Agency (IEA)

- Renewables Information 2003.

Types of Renewable Energy:- Geothermal (not strictly

renewable) Hydro Wind Waves and Tides Biomass

Solar Wood fuel Biodiesel Vegetable oil vehicles

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Why renewable energy?• Growing energy demand.

• Limited reserves of fossil fuels.

• Environmental concerns – CO2 emissions, pollution etc.

• Abundant and available everywhere (different types).

• Causes little if any environmental damage and do not deplete Earth’s natural resources.

Global Warming !!!!• The Greenhouse Effect traps heat inside the

Earth’s atmosphere. This causes our climate

increasing in temperature. This is known as

Global Warming.

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Future Green house gas Levels:-Increasing Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O),

Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), Sulphur hexafluoride

(SF6) emissions, especially in China and developing countries

Likely to double within 150 years:

• Increased coal usage.

• Increased natural gas usage.

• Increased petroleum usage.

(increased cost and decreasing supply)

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What does Renewable energy mean?

Solar: Converting the radiant energy of the sun to electrical energy.

Wind: Converting the force of wind into mechanical or electrical energy.

Biomass: Burning organic matter such as wood or agricultural materials to produce heat energy. Methane gas can be provided

from organic wastes.

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What does Renewable energy mean?

Tidal: Tidal, wave and marine current converting the movement of water intomechanical or electrical energy.

Wave Energy: Ocean wave energy is captured directly from surface waves or from pressure fluctuations below the surface. Wave power devices extract energy directly from the surface motion of ocean waves or from pressure fluctuations below the surface. Marine Current Energy: The tide is the source of "marine current" or "tidal stream" energy. Marine currents refer to a moving mass of water. Useful energy can be extracted from marine currents using completely submerged turbines and hydrofoil devices.

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What does Renewable energy mean?

Geothermal: Extracting natural heat from within the earth for direct heating and/or to produceelectricity.

Hydropower: Generating electricity from falling water.

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Renewable Energy in Hong Kong:-Solar water heating There are a number of installations for low-rise buildings in the New

Territories. The largest system installed so far in Hong Kong is at the Sheung Shui Slaughterhouse.

Building Integrated Photovoltaic (BIPV) Systems A number of BIPV systems have been installed in both public and private

projects, showcasing how photovoltaic and electrical systems can be integrated to supply power.

These projects include Wanchai Tower, EMSD Headquarters at Kai Tak, and Science Park in Shatin.

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Renewable Energy in Hong Kong:-Building Integrated Photovoltaic (BIPV) Systems A 350kW photovoltaic installation has been installed on the roof of the new

EMSD Headquarters in Kowloon Bay.

The PV array covers the whole roof of the Building The largest in HK, with 2300 PV modules covering 3,180 square meters.

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Renewable Energy in Hong Kong:-Smart Building:

Atrium: A wide, sunlit space

in the center of the building.

The Sun-scoop has 480 glass

mirrors which reflect sunlight

onto the aluminum reflectors at

the top of the atrium.

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Renewable Energy in Hong Kong:-Wind Energy:

Lamma Winds:

In Feb 2006, Hongkong Electric launched the city’s first commercial-scale wind turbine. The wind turbine has a rated capacity of 800 kW. Another to be commisioned in 2007. 2 offshore wind farms proposed.

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Lamma Winds:-

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Challenges of Renewable Energy:-1. It can be unpredictable and unreliable

The availability of wind energy depends on sufficiently high wind speeds, and the availability of solar energy depends on the presence of clear and sunny weather conditions.

2. Some applications require lots of land

For example, a wind farm that can generate 400 million units of electricity (about 1% of HK’s annual electricity consumption) may require a land space of up to 4,000 hectares.

But HK have a vast ocean and wind farms can be installed in ocean.

Big Building tops, Road barriers and noise barriers can be fitted with PV.

3. More expensive than traditional fuels

Not cost-effective. High investment.