Fossil fuels have traditionally been the world’s dominant source of energy. However, the global transition towards renewable energy is underway, driven largely by support from governments, improving economics and significant advancements in technology that have helped make different types of sustainable energy more cost competitive and more available than ever before.
How do renewable energy technologies work?
Renewable energy is typically generated from natural resources such as the sun, wind or water and is consistently replenished based on the resources themselves i.e. sunlight, wind or natural heat. There are many kinds of existing and emerging technologies, but each shares the same intention: to harness natural resources to power consumers without damaging the earth and human health.
The foundations of solar power were laid in 1839 with the discovery of the solar photovoltaic effect.1 In nearly two centuries, solar has grown to become one of the world’s fastest-growing renewable energy technologies, and by 2040, solar could comprise nearly one third of the world’s total power generation.2
There are currently two main kinds of solar technology: solar thermal, which concentrates and converts the sun’s rays into heat by using a series of reflective collectors, as well as solar photovoltaic, which converts sunlight directly into electricity by using a panel of interconnected cells joined together to form a circuit – often made with monocrystalline cells, polycrystalline cells or thin film.
People have harnessed the power of wind since early recorded history. During this time, people used wind to propel their boats, pump water and grind grain.3 Hundreds of years later, wind is one of the cheapest sources of large-scale energy in the world,4 with wind-powered generators now operating in every size and range across the world.
Wind turbines capture wind energy by lifting and turning large blades. Most turbines have two or three. These blades are connected to a rotor which is also connected to a main shaft. When rotated, the shaft (which is connected to a gear box) spins a generator to create electricity.5
Like wind power, some of the earliest innovations in water power go back centuries, where in China, trip hammers activated by the vertical-set water wheel were used to pound grain, break ore and assist in early paper-making.6
Hydroelectricity (or hydropower) is generated by the force or energy of moving water. Similar to wind power, flowing water is channelled through turning blades that are connected to a shaft and electrical generator.7 While smaller power stations generally rely on naturally flowing water sources, larger stations need dams to store the water required to produce power – many of which are built to hold irrigation or drinking water, ensuring as much value from the resource is extracted as possible.8
Biomass (or bioenergy) is a fuel developed from organic materials, such as sugar cane residue, forest debris, crops and manure.9 The energy in biomass can be converted into electricity, heat or biofuels; however, the methods for extracting energy from biomass can vary depending on the materials used.10
Some examples include conventional combustion, which is the simplest and most widely used technology for converting biomass to heat, as well as gasification – an efficient process that involves heating solids to very high temperatures in gasifiers to transform partly burnt materials into syngas – and anaerobic digestion, which is the biological breakdown of biomass in oxygen-free conditions (for example, peat swamps and other man-made environments such as landfills or purpose-built lagoons).11
Geothermal energy is heat from the earth, sourced from shallow ground, hot water or hot rock found kilometres beneath the earth’s surface.12
Sourcing energy from hot rocks generally relies on techniques employed by the oil and gas industries – for example, drilling wells beneath earth’s surface and pumping water through them.13 Water is then heated and pushed back to the surface, where it is used to drive a turbine and generator to produce electricity – only to be recycled and begin the process all over again.14