Green Energy Trends

Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants and artificial photosynthesis.^[1][2]

It is an important source of renewable energy and its technologies are broadly characterized as either passive solar or active solar depending on how they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air.

The large magnitude of solar energy available makes it a highly appealing source of electricity. The United Nations Development Programme in its 2000 World Energy Assessment found that the annual potential of solar energy was 1,575–49,837 exajoules (EJ). This is several times larger than the total world energy consumption, which was 559.8 EJ in 2012.^[3][4]

In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating global warming, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared

Science Technology

Hydropower or water power (from Greek: ὕδωρ, "water") is power derived from the energy of falling or fast-running water, which may be harnessed for useful purposes. Since ancient times, hydropower from many kinds of watermills has been used as a renewable energy source for irrigation and the operation of various mechanical devices, such as gristmills, sawmills, textile mills, trip hammers, dock cranes, domestic lifts, and ore mills. A trompe, which produces compressed air from falling water, is sometimes used to power other machinery at a distance.^[1][2]

In the late 19th century, hydropower became a source for generating electricity. Cragside in Northumberland was the first house powered by hydroelectricity in 1878^[3] and the first commercial hydroelectric power plant was built at Niagara Falls in 1879. In 1881, street lamps in the city of Niagara Falls were powered by hydropower.

Since the early 20th century, the term has been used almost exclusively in conjunction with the modern development of hydroelectric power. International institutions such as the World Bank view hydropower as a means for economic development without adding substantial amounts of carbon to the atmosphere,^[4] but dams can have significant negative social and environmental impacts.^[5]

Solar energy saves the environment

The endeavor to use 100% renewable energy for electricity, heating/cooling and transport is motivated by global warming, pollution and other environmental issues, as well as economic and energy security concerns. Shifting the total global primary energy supply to renewable sources requires a transition of the energy system. According to the Intergovernmental Panel on Climate Change there are few fundamental technological limits to integrating a portfolio of renewable energy technologies to meet most of total global energy demand. Renewable energy use has grown more quickly than even advocates anticipated.^[6] As of 2019, however, it needs to grow six times faster to limit global warming to 2 °C (3.6 °F).^[7]

100% renewable energy in a country is typically a more challenging goal than carbon neutrality. The latter is a climate mitigation target, politically decided by many countries, and may also be achieved by balancing the total carbon footprint of the country (not only emissions from energy and fuel) with carbon dioxide removal and carbon projects abroad.

In 2014, renewable sources such as wind, geothermal, solar, biomass, and burnt waste provided 19% of the total energy consumed worldwide, with roughly half of that coming from traditional use of biomass.^[8] The most important^{[clarification needed]} sector is electricity with a renewable share of 22.8%, most of it coming from hydropower with a share of 16.6%, followed by wind with 3.1%.^[8] As of 2018 according to REN21 transformation is picking up speed in the power sector, but urgent action is required in heating, cooling and transport.^[9] There are many places around the world with grids that are run almost exclusively on renewable energy. At the national level, at least 30 nations already have renewable energy contributing more than 20% of the energy supply.^{[citation needed]}

According to a review of the 181 peer-reviewed papers on 100% renewable energy which were published until 2018, "[t]he great majority of all publications highlights the technical feasibility and economic viability of 100% RE systems." While there are still many publications which focus on electricity only, there is a growing number of papers that cover different energy sectors and sector-coupled, integrated energy systems. This cross-sectoral, holistic approach is seen as an important feature of 100% renewable energy systems and is based on the assumption "that the best solutions can be found only if one focuses on the synergies between the sectors" of the energy system such as electricity, heat, transport or industry.^[10]

Professors S. Pacala and Robert H. Socolow of Princeton University have developed a series of "climate stabilization wedges" that can allow us to maintain our quality of life while avoiding catastrophic climate change, and "renewable energy sources," in aggregate, constitute the largest number of their "wedges."^[11]

Mark Z. Jacobson, professor of civil and environmental engineering at Stanford University and director of its Atmosphere and Energy program, says that producing all new energy with wind power, solar power, and hydropower by 2030 is feasible, and that existing energy supply arrangements could be replaced by 2050. Barriers to implementing the renewable energy plan are seen to be "primarily social and political, not technological or economic". Jacobson says that energy costs today with a wind, solar, and water system should be similar to today's energy costs from other optimally cost-effective strategies.^[12] The main obstacle against this scenario is the lack of political will.^[13] His conclusions have been disputed by other researchers.^[14] Jacobson published a response that disputed the piece point by point^[15] and claimed that the authors were motivated by allegiance to energy technologies that the 2015 paper excluded.^[14]

Similarly, in the United States, the independent National Research Council has noted that "sufficient domestic renewable resources exist to allow renewable electricity to play a significant role in future electricity generation and thus help confront issues related to climate change, energy security, and the escalation of energy costs ... Renewable energy is an attractive option because renewable resources available in the United States, taken collectively, can supply significantly greater amounts of electricity than the total current or projected domestic demand."^[16]

The main barriers to the widespread implementation of large-scale renewable energy and low-carbon energy strategies are political rather than technological. According to the 2013 Post Carbon Pathways report, which reviewed many international studies, the key roadblocks are: climate change denial, the fossil fuels lobby, political inaction, unsustainable energy consumption, outdated energy infrastructure, and financial constraints.