Hydropower, wind, solar, biomass and geothermal power are emerging as alternative energy to fossil fuels.
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Hydropower: River currents harness large amounts of energy, and this source of renewable energy is the world’s most popular, followed by harnessing tidal energy from the ocean . Although relatively clean, it has its drawbacks, such as displacements of local residents and wildlife occur due to large dams and higher risk of droughts.
Wind: People have harnessed wind energy for several centuries. China, US and Germany are pioneers in this source of energy. Offshore wind farms are gaining popularity, having most projects done within the past decade. The main drawback is that often it is dangerous to birds and might cause huge amounts of noise by the turbine blades .
Solar: Solar energy is gaining momentum, the installed energy capacity increased 4,300% from 2007 to 2017 . This change is led by China, Japan and the US. Although helping investors save on electricity bills in the long run, it has a long way to go and presents large upfront costs which often deter investors from making the long term sustainable decision.
Biomass: Popular in the form of biofuels, primarily ethanol and biodiesel, this source of energy produces electricity while also providing a supply of fuel. Those unfavorable for biofuels argue that it supports unsustainable agriculture leading to environmental degradation .
Geothermal: Popular in the use of heating and cooling, it is sourced from Mother Earth . Large scale extractions involve finding hot water deep underground, and smaller scale energy extractions are found only several feet underground utilized for heating in buildings. On the downside, it has a foul smell and could release hydrogen sulfide.
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