User:Clayoquot/Clean energy

Clean energy
The emissions reductions necessary to keep global warming below 2°C will require a system-wide transformation of the way energy is produced, distributed, stored, and consumed. Many climate change mitigation scenarios envision three main aspects of a low-carbon energy system:
 * The use of low-emission energy sources to produce electricity
 * Increased use of electricity instead of directly burning fossil fuels
 * Accelerated adoption of energy efficiency measures

Renewable energy sources such as wind, solar, and hydropower generally produce low GHG emissions, however some renewable energy projects raise significant sustainability concerns. Nuclear energy, etc...

1 sentence on integrating variable renewables...

Some energy-intensive technologies and processes are difficult to electrify, including aviation, shipping, and steelmaking. For some applications, the most prominent alternative to electrification is to develop a system based on sustainably-produced hydrogen fuel.

Full decarbonization of the global energy system is expected to take several decades and can mostly be achieved by deploying existing technology. The International Energy Agency states that further innovation in the energy sector, such as in battery technologies and carbon-neutral fuels, is needed to reach net-zero emissions by 2050. The transition to a zero-carbon energy system would bring strong co-benefits for human health: The WHO estimates that efforts to limit global warming to 1.5 °C could save millions of lives each year from air pollution alone. With responsible planning and management, pathways exist to provide universal access to electricity and clean cooking by 2030 in ways that are consistent with climate goals.

Clean energy
Long-term decarbonisation scenarios point to rapid and significant investment in renewable energy, which includes solar and wind power, bioenergy, geothermal energy, and hydropower. Fossil fuels accounted for 80% of the world's energy in 2018, while the remaining share was split between nuclear power and renewables; that mix is projected to change significantly over the next 30 years. Solar and wind have seen substantial growth and progress over the last few years; photovoltaic solar and onshore wind are the cheapest forms of adding new power generation capacity in most countries. Renewables represented 75% of all new electricity generation installed in 2019, with solar and wind constituting nearly all of that amount. Meanwhile, nuclear power costs are increasing amidst stagnant power share, so that nuclear power generation is now several times more expensive per megawatt-hour than wind and solar.

To achieve carbon neutrality by 2050, renewable energy would become the dominant form of electricity generation, rising to 85% or more by 2050 in some scenarios. The use of electricity for other needs, such as heating, would rise to the point where electricity becomes the largest form of overall energy supply. Investment in coal would be eliminated and coal use nearly phased out by 2050.

In transport, scenarios envision sharp increases in the market share of electric vehicles, and low carbon fuel substitution for other transportation modes like shipping. Building heating would be increasingly decarbonized with the use of technologies like heat pumps.

There are obstacles to the continued rapid development of renewables. For solar and wind power, a key challenge is their intermittency and seasonal variability. Traditionally, hydro dams with reservoirs and conventional power plants have been used when variable energy production is low. Intermittency can further be countered by demand flexibility, and by expanding battery storage and long-distance transmission to smooth variability of renewable output across wider geographic areas. Some environmental and land use concerns have been associated with large solar and wind projects, while bioenergy is often not carbon neutral and may have negative consequences for food security. Hydropower growth has been slowing and is set to decline further due to concerns about social and environmental impacts.

Low-carbon energy improves human health by minimizing climate change and has the near-term benefit of reducing air pollution deaths, which were estimated at 7 million annually in 2016. Meeting the Paris Agreement goals that limit warming to a 2 °C increase could save about a million of those lives per year by 2050, whereas limiting global warming to 1.5 °C could save millions and simultaneously increase energy security and reduce poverty.