Renewables

What Are Renewable Energy Sources?

Renewable energy comes from sources that never run out or can be naturally replaced. Unlike fossil fuels (coal, oil, gas) which will eventually be used up, renewable sources keep providing energy as long as natural processes continue.

The main renewable energy sources are:

• Water (Hydroelectric/Hydel Power) – using flowing or falling water
• Wind – using moving air
• Sun (Solar Power) – using sunlight
• Waves and Tides – using ocean movements
• Geothermal – using heat from inside the Earth
• Biomass – using plant material and organic waste

Pakistan has the potential to develop several of these renewable sources, especially hydroelectric power in the northern mountains.

1. Methods of Producing Electricity from Renewable Resources

A. Hydroelectric Power (HEP/Hydel Power)

How it works: Hydroelectric power uses the force of running or falling water to produce electricity. Here's the step-by-step process:

1. A dam is built across a river in a valley
2. Water collects behind the dam in a large reservoir (artificial lake)
3. Water flows from the reservoir through large pipes called penstocks
4. The falling water hits turbines (spinning wheels) with great force
5. The turbines turn generators in a magnetic field
6. This generates electricity which travels through power lines to homes and industries

Multi-purpose dams in Pakistan (like Tarbela, Mangla, and Warsak) serve several functions:

• Generate electricity
• Provide water for irrigation
• Control flooding
• Support fishing
• Create recreational areas

Advantages of Hydroelectric Power:

• Never runs out – as long as rivers flow, electricity can be generated
• Clean and pollution-free – no smoke, no carbon dioxide emissions, no acid rain
• Cheap to run – water is free; only maintenance costs after the dam is built
• Reliable in wet seasons – consistent power when water supply is good
• Multi-purpose benefits – irrigation, flood control, fishing, recreation
• Long-lasting – dams can work for 50-100 years
• No fuel costs – unlike thermal power stations that need constant coal/oil/gas supplies

Disadvantages of Hydroelectric Power:

• Very expensive to build – dams cost billions of rupees; requires planning, resettlement of people, building roads and tunnels, expensive machinery
• Displaces people – thousands of families must move from areas that will be flooded
• Destroys forests and farmland – large areas are permanently underwater
• Environmental damage – flooded forests decay and produce methane (a greenhouse gas); mangrove forests downstream die from reduced water flow
• Reduces downstream water – less water reaches farmers and fisheries below the dam
• Siltation problems – over time, mud and sand fill up the reservoir, reducing capacity and blocking spillways
• Unreliable in dry seasons – less rainfall means less electricity generation
• Takes years to build – cannot solve immediate energy shortages
• Earthquake risk – dams can fail during earthquakes, causing devastating floods
• Political conflicts – provinces dispute water sharing

B. Solar Power

How it works: Solar energy from the sun can be used in different ways:

Method 1 - Solar Panels (Photovoltaic):

• Rectangular solar panels are made of many solar cells
• These cells convert light energy from the sun directly into electrical energy
• Panels are placed on rooftops or in large arrays in deserts
• They should face south (in Pakistan) to collect maximum sunlight

Method 2 - Solar Water Heating:

• Black panels absorb heat from the sun
• This heat warms water directly for use in homes

Method 3 - Concentrated Solar Power:

• Mirrors in deserts reflect and concentrate sunlight onto a central tower
• The concentrated heat boils water into steam
• The steam turns turbines to generate electricity

Advantages of Solar Power:

• Unlimited source – the sun will shine for billions of years
• No pollution – clean energy with no emissions
• Good for remote areas – can provide electricity to villages far from the national grid
• Low running costs – free sunlight, only maintenance needed
• Silent operation – no noise pollution
• Easy to install – especially small panels on rooftops
• Pakistan has plenty of sunshine – especially in Sindh, Punjab, and Balochistan

Disadvantages of Solar Power:

• Low efficiency – only about 20% of sunlight is converted to electricity
• Not available at night – no electricity when the sun sets
• Reduced on cloudy days – weather affects output
• High maintenance – dust and sand must be cleaned regularly; dirty panels lose 75% efficiency
• Expensive initial cost – solar panels and equipment are costly to buy and install
• Dangerous materials – panels contain substances like cadmium which are harmful
• Requires large space – many panels needed for high power output
• Batteries needed – to store electricity for nighttime use, adding to cost

C. Wind Power

How it works:

1. Large wind turbines are installed in windy locations
2. Each turbine has blades mounted on a tall tower
3. Wind pushes the blades, making them rotate
4. The rotating blades turn a turbine connected to a generator
5. The generator produces electricity

Best locations for wind power:

• Coastal areas (sea breezes)
• Mountain passes
• Hilltops
• Open plains
• Offshore (in the sea)

Advantages of Wind Power:

• Renewable – wind will never run out
• No pollution – clean, environmentally friendly
• Free fuel – wind costs nothing
• Plenty available in Pakistan – coastal areas, mountain passes
• Can work day and night – unlike solar, wind often blows at night
• Good for remote areas – can provide electricity to villages in mountains
• Various sizes available – from small turbines for homes to large wind farms
• Attracts tourists – wind farms can be tourist attractions
• Quick to build – faster than building dams

Disadvantages of Wind Power:

• Expensive to build – turbines and towers cost a lot initially
• Unreliable – wind speed varies; no wind = no electricity
• Stops during storms – very strong winds damage turbines
• Many turbines needed – requires large areas for significant power output
• Kills birds – flying birds can hit the blades
• Noise pollution – turbines create constant humming sounds
• Spoils scenery – some people find them ugly
• Interferes with signals – can disrupt TV and radio reception
• Location-specific – only works in windy areas

D. Wave and Tidal Power

How it works: Similar to wind power, but turbines are placed underwater on the seabed or floating on the surface:

Wave Power devices:

• Sea Snakes (Pelamis) – floating devices on the surface that move with waves, pumping hydraulic fluid to generate electricity
• Underwater turbines – like underwater windmills turned by wave movements

Tidal Power devices:

• Tidal turbines – installed on the seabed, turned by the force of tides moving in and out
• Tidal barrages – dams built across estuaries to capture tidal energy

Advantages of Wave and Tidal Power:

• Predictable – tides follow regular patterns (unlike wind or sun)
• No pollution – clean energy
• Never runs out – waves and tides are constant
• Reliable – tides happen twice daily regardless of weather

Disadvantages of Wave and Tidal Power:

• Very expensive – requires significant research and development
• Difficult to install and maintain – underwater machinery is hard to fix
• Low electricity yield – current technology doesn't produce much power
• Damages marine life – turbines can harm fish and sea creatures
• Corrodes quickly – seawater rusts metal equipment
• Limited locations – only works on coasts; Pakistan has limited suitable sites
• Still experimental – technology not yet fully developed

E. Geothermal Power

How it works:

1. In areas with volcanic activity or hot rocks underground, two pipes are drilled deep into the Earth
2. Cold water is pumped down through one pipe
3. The water is heated by hot rocks in the Earth's crust (heated by magma below)
4. Hot water or steam comes back up through the second pipe
5. Through a heat exchanger, this heat turns water in another pipe system into steam
6. The steam turns turbines to generate electricity

In Pakistan: Some potential exists in Azad Kashmir near Kotli, where hot springs indicate underground heat.

Advantages of Geothermal Power:

• Reliable – available 24/7, unlike solar or wind
• Clean – minimal pollution
• Low running costs – once installed, heat is free
• Small land area needed – compared to solar or wind farms

Disadvantages of Geothermal Power:

• Very location-specific – only works where hot rocks are near the surface
• Limited in Pakistan – only a few areas have potential
• Can release carbon dioxide – some underground gases escape, contributing to global warming
• Expensive to drill – deep drilling costs are very high
• Risk of earthquakes – drilling can trigger minor tremors
• Water contamination risk – chemicals from deep underground can pollute water

F. Biomass and Biogas

How it works:

Direct Burning:

• Dead leaves, branches, wood, and agricultural waste are burned
• The heat boils water into steam
• Steam turns turbines to generate electricity

Biogas Production:

1. Animal dung (mainly cow and buffalo) is put into a closed container called a biogas plant
2. The container is sealed to keep out oxygen
3. Bacteria and micro-organisms digest the waste
4. This produces methane gas (biogas)
5. The gas is used for cooking or generating electricity in small generators

In Pakistan: Biogas is particularly useful in rural areas where animals are common. Small-scale biogas plants help families cook and light their homes.

Advantages of Biomass/Biogas:

• Uses waste – agricultural waste and animal dung that would otherwise be useless
• Reduces deforestation – less need to cut trees for firewood
• Good for rural areas – villages with livestock can become self-sufficient
• Small-scale and cheap – individual families can install small biogas plants
• Provides fertilizer – leftover waste from biogas plants is excellent manure
• Locally available – no need to import fuel

Disadvantages of Biomass/Biogas:

• Limited energy output – produces small amounts of electricity
• Not suitable for large-scale needs – cannot power cities or industries
• Needs constant supply – requires regular feeding with waste
• Smell – animal waste can create unpleasant odors during collection and processing
• Time-consuming – collecting and processing waste takes effort
• Seasonal variations – less waste available in some seasons