Climate change: what are renewable energies?

In any discussion of climate change, renewables usually top the list of changes the world will need to make to avoid the worst effects of rising temperatures. This is because renewable energy sources, such as solar and wind energy, do not emit carbon dioxide and other greenhouse gases that contribute to global warming.

Clean energy has many advantages that make it desirable, other than being “green”. This growing sector creates jobs, makes electricity networks more resilient, expands access to energy in developing countries and helps reduce electricity bills. All of these factors have contributed to the resurgence of renewable energy in recent years, with wind and solar setting new records in electricity generation.

Over the past 150 years or so, humans have made extensive use of coal, oil, and other fossil fuels to provide the energy needed to light a light bulb, run vehicles, or start a factory. Fossil fuels are part of nearly every aspect of our lives, and as a result, greenhouse gas emissions from their combustion have reached historically unprecedented levels.

Greenhouse gases trap heat in the atmosphere, which would otherwise be dumped into space, so average Earth surface temperatures rise. Global warming is a symptom of climate change, which is the term scientists currently prefer to describe the complex changes affecting our climate system. Climate change is not just about rising average temperatures, but it is also translating into extreme weather events, migrations of wildlife populations and their habitats, sea level rise and a whole host of other consequences.

Of course, renewable energies, like any other source of energy, have negative sides and are called into question. One ongoing discussion concerns the definition of renewable energy itself. Strictly speaking, renewable energy means exactly what its name says: it can be defined as always available, or, according to the Energy Information Administration, as “virtually inexhaustible” energy. But “renewable” does not necessarily mean sustainability, argue those who oppose the use of corn-derived ethanol or large hydroelectric dams. It also does not include other low- or no-emission energy sources that have their advocates, such as energy efficiency and nuclear power.

Renewable Energy Guide

HydroelectricityFor centuries, energy obtained from the flow of rivers has been exploited, with dams used to control the flow of water. Hydropower is by far the largest source of renewable energy and the largest producers are China, Brazil, Canada, the United States and Russia. Hydroelectric power is theoretically a clean source of energy, and it can be restored with rain and snow, but it also has various drawbacks.

Large dams can destroy the ecosystems of rivers and the surrounding communities, causing harm to animals and displacing the populations that live there. Hydropower generation is subject to sludge formation which can damage its capacity and damage its plants. Dehydration can also cause problems. According to a 2018 study, in the western United States, CO2 emissions over 15 years were 100 megatons higher than they would normally have been, as users switched to coal and gas to replace CO2. Hydroelectric power was lost due to drought. Hydroelectric power, at its full potential, also includes emissions problems in the form of methane that arises from the decomposition of organic matter within ponds.

Dams aren’t the only way to use water for energy – there are tidal cycle-based projects around the world that aim to capture the ocean’s natural rhythms. Marine power projects are currently estimated to generate 500 megawatts of power, less than one percent of total renewable energy, but the potential is infinitely greater. Programs such as the Saltire Prize in Scotland have fostered innovation in this area.

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