What exactly is renewable energy and why is it so important in the battle against climate change?
The transition towards renewables such as solar and wind energy is critical part of meeting the goals of the Paris Agreement, which aims to limit the rise of global average temperatures to well below 2 degrees Celsius, and ideally below 1.5 degrees Celsius above pre-industrial levels. The good news is that this transition is taking place, with a third of global power capacity in 2018 based on renewable energy, according to the International Renewable Energy Agency.
And as a ‘Recover Better’ mindset is needed in a post-COVID world, its vital that renewables keep being prioritised. So what are we talking about when we talk about renewables? Renewables refer to any form of energy that’s not finite – so everything from wind and solar to biomass. In the coming months, we will do a deep dive on each of these renewables, but for now here’s a brief guide to the main renewable energy sources.
Solar Energy
Solar energy is the most abundant clean energy source on the planet. It’s produced by nuclear fusion that takes place in the sun – which occurs when protons of hydrogen atoms collide in the sun’s core and create a helium atom. Solar panels capture this energy from the sun, and then either convert solar into power or heat water (solar thermal). And while solar farms can take up a lot of land, most solar technology is now located on rooftops, and increasingly in windows. It is one of the cleanest, and cheapest sources of energy available to us, with the International Energy Agency (IEA) declaring last year that some solar power schemes offer “the cheapest electricity in history.”
Wind Energy
Wind energy is the most competitively priced renewable technology in many markets, and its relatively low operating costs have seen the number of wind turbines increase globally in recent years. In the EU for example, there was a wind power capacity of 6,453MW in 1988, which rose to 192,231MW in 2019. Wind turbines work when wind turns the blades of a turbine around a rotor, which in turn spins a generator, which creates electricity. There are two types of wind farms: onshore and offshore. Offshore wind farms have the advantage of frequent windy conditions; they also avoid the objections that some residents have about onshore wind farms spoiling their views. The downside of wind farms is the effect they can have on local ecology (particular bird and bat populations).
Hydropower
Water is one of the oldest sources of energy, having been used for more than 2,000 years to power water mills, while hydropower has been used to generate electricity since the late 19th century. Usually built inside dams, hydroelectric power plants push stored water through giant turbines to generate electricity. Hydropower will account for 16% of global electricity demand by 2023, according to the IEA , and so the sector plays a vital role in the implementation of the Paris Agreement. The development of hydropower, however, does not come without environmental and social costs. Deforestation, marine life impacts and the displacement of local populations can be among its negative consequences, brought about especially by large-scale projects. The effects of climate change also have an impact on the power production; for example, between 2014 and 2017 in Brazil, an unprecedented drought reduced water pressure in hydroelectric plants, resulting in higher water consumption tariffs. The contribution of the hydropower sector to the goals of the Paris Agreement, therefore, needs to be considered not only in terms of avoiding greenhouse gas emissions, but also in promoting projects that ensure that the impact of large projects is minimized.
Bioenergy
Bioenergy is a type of energy generated when we burn biomass fuel. There are four types of biomass that can be made into biomass fuel: Wood residue (such as low-value tree parts sourced from forests during felling); Farm waste (such as manure, straw and food production leftovers); Energy crops (such as wheat, oilseed, silage); and organic waste (such as food waste and used cooking oil). The International Energy Agency referred to modern bioenergy as the “overlooked giant” of renewable energy, with it responsible for half of all renewable energy consumed in 2017. It is not without its issues – biomass energy still produces emissions, in particular methane from animal waste, and the use of wood in biomass power plants can be a contributing factor to deforestation. Also, “first-generation” biofuels produced ethanol from food sources such as sugarcane and corn, which led to increased food prices. We are now see “fourth-generation biofuels”, which avoid this problem by using genetically modified algae to enhance biofuel production.
Geothermal Energy
This type of energy takes the heat from geothermal reservoirs beneath the surface of the earth and converts it to energy. It has been used for bathing and heating for centuries, but is now used for electricity generation. One example of this is in Iceland, which sources 80% of its energy requirements from geothermal and hydroelectric power. It works in a relatively simple way, pumping the heat present just under the surface of the Earth, which heats buildings in the winter and then extracts the heat from buildings in the summer, and transfers it back underground. The benefits of this type of energy are myriad: geothermal fields produce practically no emissions, it is consistent, and geothermal heat pump systems use 25-50% less electricity than conventional heating systems. Shallow geothermal fields are fairly common and are today being used in about 90 countries, and it used in multiple cities for heating, such as in Paris, where for example, the Radio France building is run on shallow geothermal energy.
Marine Energy
Marine, or ocean energy refers to all types of energy that can be harnessed from the sea, such as from waves, tidal streams, ocean currents, ocean thermal and tidal ranges. This is done by exploiting the power of waves and tides, as well as differences in sea temperatures and salinity. This type of energy is of course very abundant, with 71% of the planet covered by oceans, however most of the technology around it is still in its infancy. The projects that do exist use technology such as wave power converters, tidal turbines, ocean current turbines and ocean thermal energy converters. While this infrastructure does effect underwater wildlife, the potential of marine energy is huge, and it’s a sector that is set to grow in the coming decades.
What can I do to help?
Look at your local energy suppliers and switch to the greenest one – in many countries, energy suppliers are required to disclose the sources of the energy they generate, and more and more suppliers are offering 100% renewable energy options. If none of your energy suppliers offer 100% green energy, find out who is offering the highest percentage, and choose them. Make sure your home is properly insulated and if possible, install solar panels or solar water heaters.