Renewable Energy: The Green Options

Renewable energy is defined as an energy that is generated from natural energy sources that are continually replenished. It includes renewable sources such as solar, wind, geothermal, hydropower, and biomass.

Renewable energy is important because it provides a clean energy source of power that does not contribute to climate change or global warming. Additionally, it can help reduce our dependence on fossil fuels and provide an alternative to the current reliance on nonrenewable resources.  

Renewable energy sources are a green option for providing clean, sustainable power and should be considered as a viable option by all.

Solar Energy

If we could capture all of the energy that the earth receives from the sun in a single day, we would be able to meet global energy needs for 20 years. 

Two prominent solar energy technologies are solar photovoltaic (PV) and concentrated solar power (CSP). 

Photovoltaic cells are the technology used in solar panels. PV Solar panels can be installed directly at their point of use to power buildings and other permanent facilities, or employed as portable sources of power. 

This makes Solar Photovoltaic energy a versatile and accessible form of renewable energy.

Concentrated Solar Power (CSP) is a process of converting solar energy to thermal energy. 

Precisely angled mirrors direct the sun’s energy into a “high temperature fluid”, which can then be stored in tanks. These storage tanks allow us to make use of the sun’s energy at all hours of the day and night.

Wind Energy 

Modern wind turbines operate on a very simple principle. Wind pushes the blades of a fan, and that spinning motion is converted from kinetic to electric energy by a generator. 

Both offshore and onshore winds can be captured this way. Humans have been harnessing wind energy to power machines such as pumps and grain mills since as early as 700-900 AD.

While initial installation costs can be high, modern wind farms are becoming more and more affordable. 

The ongoing costs and maintenance of wind farms is much lower than that associated with fossil fuels. As long as wind farms are strategically placed, they present an excellent source of renewable energy.

Wind energy is not just restricted to wind farms, wind on a smaller scale can be used to power off grid homes and other home and leisure properties such as boats.

Hydro Energy

Hydropower is the giant of renewable energy; producing more electricity worldwide than all other forms of clean energy combined. 

Not only that, it is already a serious competitor to fossil fuels! Hydropower is currently the third greatest producer of global energy.

Hydropower functions on a similar principle to wind power. The flow of water in a stream, river, or from a reservoir lake, pushes the blades of a turbine. The motion of water is then converted by the turbine from kinetic to electrical energy.

Large scale hydropower takes the form of paired dams and reservoir lakes. Damming a river and creating a reservoir allows for reliable production of hydropower all year round. 

These hydropower plants supply “almost 30% of the world’s capacity for flexible electricity supply, but they have the potential to provide even more”.

The construction of dams and reservoirs necessary for large scale hydropower can have environmental drawbacks. 

Fortunately, this doesn’t rule hydropower out as a source of renewable green energy. Small scale hydropower is generated without damming rivers, making it the cleanest available source of  energy. 

Geothermal Energy

Geothermal energy is created by the earth’s internal heat. This is used directly for heating and cooling  buildings or bodies of water, desalination, or even agricultural processing. 

Geothermal energy can also be converted to electricity in geothermal power plants. Geothermal power plants are virtually unaffected by weather systems, giving them an advantage over hydro, wind, and solar. 

This renewable energy is readily available, creates close to zero liquid waste, and uses relatively little land.

Some geothermal power plants even implement a dual model. They use geothermal energy both for electricity generation and as a direct source of heat. These dual function models are extremely efficient and sustainable.

Biomass Energy

Biomass energy covers a range of energy sources, from the wood you use to build a campfire through to innovations like biodiesel. Many “living or once living organisms” can be used as sources of biomass.

We can divide sources of biomass into:

• Wood-based Biomass 
• Agricultural Biomass 
• Industrial Biomass 
• Biogas 
• Biofuels (such as ethanol or biodiesel).

The thing that connects all of these types of biomass is the fundamental approach to extracting energy from them. 

They can be burned to provide immediate thermal energy, or as a means of electricity generation. Biomass can also be converted into fuels, such as biodiesel or charcoal and stored for subsequent use.

Although biomass is a plentiful and renewable source of energy, it is not considered to be the greenest or cleanest resource. 

The production and combustion of biofuels and other sources of biomass energy generally result in solid, gaseous, and liquid pollutant byproducts. 

Fortunately, we do have some capacity to mitigate pollution by finding secondary uses for byproducts, alongside environmental control technologies.

Tidal Energy

Tidal energy is harnessed two ways; via tidal stream energy, or via tidal range energy. Once you have a grasp on wind and hydro energy, tidal energy is simple to understand.

Stream energy is captured in locations where there are strong predictable tidal changes. 

Turbines — just like the ones used in wind energy — are installed in shallow water. The movement of water that accompanies shifting tides spin the turbines and generate electricity.

Tidal range energy is comparable to the use of dams and reservoirs in large scale hydropower. Barrages are constructed on coastlines to create artificial bays. 

These bays accentuate the natural tidal movement of the ocean. Turbines in these artificial bays (known as basins) convert the kinetic energy of the ocean’s movement into electricity.

Tidal energy should be used in countries with particularly high tides — such as the United Kingdom. 

The advantage of tidal energy is the predictable and constant momentum of the tides. Where winds can drop or the sun can be obscured, tides never stop.

Fuel Cells

Fuel cells generate electricity by suspending an electrolyte between two electrodes — working on a similar principle to a battery. 

When hydrogen is used to generate electricity within a fuel cell, the only by products produced are water and heat. Water and heat are (at their best) valuable resources, or (at their worst) environmentally harmless waste products.

There are six common electrolytes used to power fuel cells. Each of these types of fuel cells is optimized for different applications, for example:

• Polymer Electrolyte Membrane — powered by hydrogen and optimized for transportation and vehicle applications
• Direct Methanol — powered by pure methanol and optimized for portable computers and smart devices
• Alkaline — powered by potassium hydroxide and used to generate electricity and water for United States spacecraft
• Phosphoric Acid — powered by liquid phosphoric acid and optimized for stationary power generation or large vehicles
• Molten Carbonate — powered by a molten carbonate salt mixture and optimized for industrial or military applications
• Solid Oxide — powered by a ceramic compound and optimized for applications that require both heat and electricity
• Reversible Fuel Cells — powered by oxygen and hydrogen. These fuel cells recycle waste product water back into the fuel sources oxygen and hydrogen. These fuels can be stored for future use.

• Polymer Electrolyte Membrane — powered by hydrogen and optimized for transportation and vehicle applications
• Direct Methanol — powered by pure methanol and optimized for portable computers and smart devices
• Alkaline — powered by potassium hydroxide and used to generate electricity and water for United States spacecraft
• Phosphoric Acid — powered by liquid phosphoric acid and optimized for stationary power generation or large vehicles
• Molten Carbonate — powered by a molten carbonate salt mixture and optimized for industrial or military applications
• Solid Oxide — powered by a ceramic compound and optimized for applications that require both heat and electricity
• Reversible Fuel Cells — powered by oxygen and hydrogen. These fuel cells recycle waste product water back into the fuel sources oxygen and hydrogen. These fuels can be stored for future use.

Ocean Thermal Energy Conversion 

Ocean Thermal Energy Conversion (OTEC) exploits the heat difference between the shallow and deep waters of the ocean to generate electricity. 

Warm water acts as a heat source, and cold water as a heat sink. Sea water is drawn through a turbine generator by the twin processes of evaporation and condensation, before it is discharged back into the ocean.

Because equatorial regions have the greatest contrast between deep and shallow water temperatures, they are ideal for OTEC installations. 

OTEC heat engines can be used as twin function desalination and electrical plants. 

This twin function has incredible potential for the growth of the  small island states most critically affected by global warming.

In Conclusion

Solar and wind energy alone “have the potential to meet global electricity demand 100 times over”. Imagine the potential energy of all of the discussed renewable sources combined!

By implementing these renewable energy sources, we can provide a sustainable option for any given energy need. 

With renewable energy, we can reduce, re-use, and detoxify pollutants. Our green future will be built with the power of renewable energy.