Renewable Energy Resources in the Philippines

1. Geothermal Energy – is thermal or heat energy from deep within the earth.

    Geothermal reservoir – is a suitable spot for the extraction of geothermal energy.

               Elements of a Geothermal Reservoir

·         a heat source; this is the magma located deep beneath the earth’s crust;

·         a reservoir made of permeable rock for holding water;

·         a caprock which serves as a seal and prevents water and steam from escaping.

·         and water which serves as the medium for transporting the heat to the surface. The water is replenished by rainwater which seeps through the cracks and pores in the rock layers.

                      How is Geothermal Energy Utilized?

The current and most widespread use of geothermal is in the production of electricity. This process requires exploration for suitable geothermal reservoirs. The reservoir must be close enough to the surface so that drilling will not be very expensive.

The production well that is drilled will serve as the source of steam or hot water. The steam is then used to drive very large turbines which convert the mechanical energy in the steam into electrical energy.

The used steam is sent to the cooling towers where it is condensed back into water and reinjected into the ground through an injection well. This is done to replace the water that was taken out of the reservoir. In this way, the geothermal plant is able to sustain its energy source.

                      Advantages of Geothermal Energy

1. More reliable compared to other renewable energy sources.

2. The supply of steam is fairly constant and power generation is not dependent on the                                                                                  fluctuations in the supply of oil.

3. Decreases reliance om imported oil.

4. Less polluting to the environment.

5. Help create new jobs and contribute to local funds and the development of countryside.

                       Disadvantages of Geothermal Energy

1. A geothermal plant spews out sulfur and nitrogen oxides and carbon dioxide that will fill two pickup trucks in a month.

2. Geothermal plants can cause surface disturbance during the construction phase, contamination of lakes and rivers, and noise pollution during well discharge.

2. Hydroelectric Power

                       How is Hydroelectric Power Utilized?

Hydroelectric power requires a high dam or waterfall. In most cases, a dam is used. Water is collected behind the dam and is allowed to flow out through an opening at the bottom. The flowing water spins a turbine generator which then generates electricity. 

The spent water coming out of the turbine can still be used for irrigation or as a water supply for homes.

For maximum output, the kinetic energy of the water must be greatest so that most of this energy is transferred to the turbine. With a waterfall, where would the kinetic energy of the water be greatest? The water flow at the bottom has the greatest speed and kinetic energy. This is also true with a dam. A turbine generator is therefore placed at the bottom of a dam or waterfall so that the turbine can spin faster and generate more electricity.

                      Advantages of Hydroelectric Power

1. Has no emissions of carbon dioxide, sulfur or any other pollutant.

2. Start up much faster, making them ideal for supplying energy during sudden increases in demand

3. Is simpler and requires fewer people to operate and maintain.

                      Disadvantages of Hydroelectric Power

1. Dams can cause flooding of watersheds, destroying flora and fauna.

2. Relocation of indigenous tribes living in the mountains.

3. Dam failure due to earthquake or excessive rainfall can result in flooding and the deaths of thousands of people.

4. Dams can be filled with silt over time, shortening their lifespan.

Examples of Hydroelectric Plant in the Philippines

                 Angat Dam in Norzagaray, Bulacan

San Roque Dam, San Manuel, Pangasinan

3. Wind Energy

                  How is Wind Energy Utilized?

Wind energy for the generation of electricity. As with the other means of harnessing energy, this also relies on a turbine – a wind turbine.

There are two main designs for wind turbines currently in use – the horizontal axis and the vertical axis wind turbines. Of the two, the horizontal axis wind turbine is more widely used and studied.

A horizontal axis has the following components:

·         Blades – harness the wind’s kinetic energy, transforming it into rotational kinetic energy.

·         Gear box – contains the mechanical parts for increasing the rotational speed for turning the generator.

·         Generator – transforms mechanical energy into electrical energy.

·         Directional mechanism – provides a means for swinging the blades into the wind for maximum efficiency.

·         Protection mechanism – the brake is activated when the conditions are not ideal. If the wind is too weak, operation is not efficient. If the wind is too strong, the brakes prevent the rotor from spinning and causing possible damage.

·         Tower – raises the turbine well above the ground to avoid turbulent winds and to expose the blade to higher wind speeds found at greater elevations.

An alternative design is the vertical axis wind turbine, so called because it rotates about a vertical axis much like an eggbeater. Because the wind is perpendicular to the axis of rotation, this turbine can utilize wind blowing from any direction and does not require a directional mechanism. The generator and the gearbox can also be conveniently located at ground level so there is no need for a tower. To reduce stress, the blades are made from lightweight but strong composite materials.

The amount of energy that can be extracted from the wind is determined by three physical principles.

·         The power generated by a turbine is highly dependent on wind speed, Doubling the wind speed results in 8 times more power; triple the wind speed means 27 times more power. To be economical, wind speeds in a given place must be at least 4-5 m/s.

·         The greater the length of the blades, the greater the generated power. Doubling the blade length increases the power four times; triple the blade lengths results in 9 times more power.

·         The maximum efficiency of a wind turbine is 59%

Horizontal axis wind turbines tend to be more efficient than the vertical axis designs. Some designs can extract up to 45% of available energy from the wind. But since the blade and the generator have to be at the top of the tower, turbines with large capacities tend to be expensive.

                      Advantages of Wind Energy

1. Wind power is one of the most environment friendly resources available.

2. It is widely available I our country,

3. Wind turbine technology is mature and there are advanced systems that are both cheaper and more efficient than previous designs

4. Wind turbines can be installed in uninhabited areas such as mountains and hills or integrated with existing farm lands.

                      Disadvantages of Wind Energy

1. Wind turbine designs for our country have to be very strong to be able to withstand strong winds. This makes these turbines more expensive.

2. The amount of available wind energy changes from time to time. A way of storing energy must be available to provide power during periods of calm or light winds.

3. Can cause some visual and noise pollution.

Example of Wind Energy in the Philippines is the Bangui Windmill in Pagudpud, Ilocos Norte

4. Solar Energy

                      How is Solar Energy Utilized?

There are several ways of using solar energy but the most widely used and most appropriate for our country is the conversion of sunlight directly into electricity. This is done through the use of solar cells (also known as photovoltaic cells, or PV cells).

A PV cell is made of a semiconductor material, usually silicon. A semiconductor material is a substance which is neither a conductor nor an insulator. Addition of very small quantities of another substance, such as boron, to silicon changes its electrical properties. This results in n-type (negatively charged) and p-type (positively charged) semiconductors. A PV cell is formed by sandwiching an n-type and a p-type material together. When the PV cell is exposed to light, electrons are liberated from the n-type material. By attaching a load, such as light bulb, we can draw electricity from the PV cell. Several PV cells connected together make up a PV panel.

Three types of Solar Cells

·         Single-crystal solar cells are made from a large crystal of very pure silicon that has been grown under high temperatures (about 1400^oC). Single-crystal cells are efficient but the manufacturing process is very expensive.

·         Polycrystalline solar cells are simpler and cheaper to make. Molten silicon is placed in moulds then cut into wafers to produce polycrystalline cells. But although these cells are cheaper, they are not as efficient as single-crystal PV cells.

·         Thin-film solar cells are made by depositing very thin films (thinner than a human hair) of silicon on a substrate such as glass. Because they are so thin, these cells require less silicon and can be deposited on flexible materials such as plastic.

                        Advantages of Solar Energy

·         PV cells require very little maintenance and can be located in remote sites that do not have direct access to the main electricity grid

·         They are quiet and nonpolluting.

·         Because they have no moving parts, PV cells are expected to last a long time.

        

                       Disadvantages of Solar Energy

·         Initial cost system is very high.

·         There are very few technicians for PV system.

·         It requires a large hectare of land.