Sustainable energy/ja: Difference between revisions

Reducing the time and the cost of building new nuclear plants have been goals for decades but [[Economics of nuclear power plants|costs remain high]] and timescales long. Various new forms of nuclear energy are in development, hoping to address the drawbacks of conventional plants. [[Fast breeder]] reactors are capable of [[Nuclear reprocessing|recycling nuclear waste]] and therefore can significantly reduce the amount of waste that requires [[Deep geological repository|geological disposal]], but have not yet been deployed on a large-scale commercial basis. [[Thorium-based nuclear power|Nuclear power based on thorium]] (rather than uranium) may be able to provide higher energy security for countries that do not have a large supply of uranium. [[Small modular reactors]] may have several advantages over current large reactors: It should be possible to build them faster and their modularization would allow for cost reductions via [[learning-by-doing]]. They are also considered safer to use than traditional power plants.

Several countries are attempting to develop [[Fusion power|nuclear fusion]] reactors, which would generate small amounts of waste and no risk of explosions. Although fusion power has taken steps forward in the lab, the multi-decade timescale needed to bring it to commercialization and then scale means it will not contribute to a 2050 net zero goal for climate change mitigation.

==Energy system transformation==

{{Main|Energy transition}}

[[File:2015- Investment in clean energy - IEA.svg |thumb |By 2025, investment in the energy transition had grown to about twice that for [[fossil fuel]]s (oil, natural gas and coal).]]

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=== Decarbonisation of the global energy system ===

The emissions reductions necessary to keep global warming below 2{{Nbsp}}°C will require a system-wide transformation of the way energy is produced, distributed, stored, and consumed. For a society to replace one form of energy with another, multiple technologies and behaviours in the energy system must change. For example, transitioning from oil to solar power as the energy source for cars requires the generation of solar electricity, modifications to the electrical grid to accommodate fluctuations in solar panel output or the introduction of variable battery chargers and higher overall demand, adoption of [[electric cars]], and networks of [[Electric vehicle charging network|electric vehicle charging]] facilities and repair shops.

Many climate change mitigation pathways envision three main aspects of a low-carbon energy system:

* The use of low-emission energy sources to produce electricity

* [[Electrification]] – that is increased use of electricity instead of directly burning fossil fuels

* Accelerated adoption of energy efficiency measures

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Some energy-intensive technologies and processes are difficult to electrify, including aviation, shipping, and steelmaking. There are several options for reducing the emissions from these sectors: biofuels and synthetic [[carbon-neutral fuels]] can power many vehicles that are designed to burn fossil fuels, however biofuels cannot be sustainably produced in the quantities needed and synthetic fuels are currently very expensive. For some applications, the most prominent alternative to electrification is to develop a system based on sustainably-produced [[hydrogen fuel]].

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Full decarbonisation of the global energy system is expected to take several decades and can mostly be achieved with existing technologies.  In the IEA's proposal for achieving net zero emissions by 2050, about 35% of the reduction in emissions depends on technologies that are still in development as of 2023. Technologies that are relatively immature include batteries  and processes to create carbon-neutral fuels. Developing new technologies requires research and development, [[technology demonstration|demonstration]], and [[experience curve|cost reductions via deployment]].

The transition to a zero-carbon energy system will bring strong [[Co-benefits of climate change mitigation|co-benefits]] for human health: The World Health Organization estimates that efforts to limit global warming to 1.5&nbsp;°C could save millions of lives each year from reductions to air pollution alone. With good planning and management, pathways exist to provide universal [[Rural electrification|access to electricity]] and [[clean cooking]] by 2030 in ways that are consistent with climate goals. Historically, several countries have made rapid economic gains through coal usage.} However, there remains a window of opportunity for many poor countries and regions to "[[Leapfrogging|leapfrog]]" fossil fuel dependency by developing their energy systems based on renewables, given adequate international investment and knowledge transfer.

===Integrating variable energy sources===

{{See also|Grid balancing}}[[File:SoSie+SoSchiff Ansicht.jpg|thumb|alt=Short terraces of houses, with their entire sloping roofs covered with solar panels| Buildings in the [[Solar Settlement at Schlierberg]], Germany, produce more energy than they consume. They incorporate rooftop solar panels and are built for maximum energy efficiency.]]

To deliver reliable electricity from [[variable renewable energy]] sources such as wind and solar, electrical power systems require flexibility. Most [[electrical grid]]s were constructed for non-intermittent energy sources such as coal-fired power plants. As larger amounts of solar and wind energy are integrated into the grid, changes have to be made to the energy system to ensure that the supply of electricity is matched to demand. In 2019, these sources generated 8.5% of worldwide electricity, a share that has grown rapidly.

There are various ways to make the electricity system more flexible. In many places, wind and solar generation are complementary on a daily and a seasonal scale: there is more wind during the night and in winter when solar energy production is low. Linking different geographical regions through [[High-voltage direct current|long-distance transmission lines]] allows for further cancelling out of variability. Energy demand can be shifted in time through [[energy demand management]] and the use of [[smart grids]], matching the times when variable energy production is highest. With [[grid energy storage]], energy produced in excess can be released when needed. Further flexibility could be provided from [[sector coupling]], that is coupling the electricity sector to the heat and mobility sector via [[power-to-heat]]-systems and electric vehicles.

Building overcapacity for wind and solar generation can help ensure that enough electricity is produced even during poor weather. In optimal weather, energy generation may have to be [[Curtailment (electricity)|curtailed]] if excess electricity cannot be used or stored. The final demand-supply mismatch may be covered by using [[Dispatchable generation|dispatchable energy sources]] such as hydropower, bioenergy, or natural gas.

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====Energy storage====

{{Main|Energy storage|Grid energy storage}}

|image1 = 20240706 Energy storage - renewable energy - battery - 100 ms.gif |caption1= Energy from renewable sources is converted to potential energy that is stored in devices such as electric batteries. The stored potential energy is later converted to electricity and added to the power grid, even when the original source is unavailable.

| image2 = 1 MW 4 MWh Turner Energy Storage Project in Pullman, WA.jpg |caption2= A battery storage facility

Energy storage helps overcome barriers to intermittent renewable energy and is an important aspect of a sustainable energy system. The most commonly used and available storage method is [[pumped-storage hydroelectricity]], which requires locations with large differences in height and access to water. [[Battery storage|Batteries]], especially [[Lithium-ion battery|lithium-ion batteries]], are also deployed widely.  Batteries typically store electricity for short periods; research is ongoing into technology with sufficient capacity to last through seasons.

Costs of utility-scale batteries in the US have fallen by around 70% since 2015, however the cost and low [[energy density]] of batteries makes them impractical for the very large energy storage needed to balance inter-seasonal  variations in energy production. Pumped hydro storage and [[power-to-gas]] (converting electricity to gas and back) with capacity for multi-month usage has been implemented in some locations. According to the International Energy Agency (IEA), global battery storage capacity is expected to increase nearly 15-fold between 2021 and 2030, driven by falling costs and increased investment in clean infrastructure.

=== Electrification ===

{{main|Electrification}}

[[File:Heat Pump.jpg|thumb|alt=Photograph two fans, the outdoor section of a heat pump|The outdoor section of a [[heat pump]]. In contrast to oil and gas boilers, they use electricity and are highly efficient. As such, electrification of heating can significantly reduce emissions.]]

Compared to the rest of the energy system, emissions can be reduced much faster in the electricity sector. As of 2019, 37% of global electricity is produced from low-carbon sources (renewables and nuclear energy). Fossil fuels, primarily coal, produce the rest of the electricity supply. One of the easiest and fastest ways to reduce greenhouse gas emissions is to phase out coal-fired power plants and increase renewable electricity generation.

Climate change mitigation pathways envision extensive electrification—the use of electricity as a substitute for the direct burning of fossil fuels for heating buildings and for transport. Ambitious climate policy would see a doubling of energy share consumed as electricity by 2050, from 20% in 2020.

One of the challenges in providing universal access to electricity is distributing power to rural areas. Off-grid and [[Mini-grids|mini-grid]] systems based on renewable energy, such as small solar PV installations that generate and store enough electricity for a village, are important solutions. Wider access to reliable electricity would lead to less use of [[kerosene lighting]] and diesel generators, which are currently common in the developing world.

Infrastructure for generating and storing renewable electricity requires minerals and metals, such as [[cobalt]] and [[lithium]] for batteries and [[copper]] for solar panels. Recycling can meet some of this demand if product lifecycles are well-designed, however achieving net zero emissions would still require major increases in mining for 17 types of metals and minerals. A small group of countries or companies sometimes dominate the markets for these commodities, raising geopolitical concerns. Most of the world's cobalt, for instance, is [[Mining industry of the Democratic Republic of the Congo|mined in the Democratic Republic of the Congo]], a politically unstable region where mining is often associated with human rights risks. More diverse geographical sourcing may ensure a more flexible and less brittle [[supply chain]].

===Hydrogen===

{{Main|Hydrogen economy}}

Hydrogen gas is widely discussed as a fuel with potential to reduce greenhouse gas emissions. This requires hydrogen to be produced cleanly, in quantities to supply in sectors and applications where cheaper and more energy efficient [[Climate change mitigation|mitigation]] alternatives are limited. These applications include heavy industry and long-distance transport.

Hydrogen can be deployed as an energy source in [[fuel cells]] to produce electricity, or via combustion to generate heat. When hydrogen is consumed in fuel cells, the only emission at the point of use is water vapour. Combustion of hydrogen can lead to the thermal formation of harmful [[NOx|nitrogen oxides]]. The overall lifecycle emissions of hydrogen depend on how it is produced. Nearly all of the world's current supply of hydrogen is created from fossil fuels.

The main method of producing hydrogen is [[steam methane reforming]], in which hydrogen is produced from a chemical reaction between steam and [[methane]], the main component of natural gas. Producing one tonne of hydrogen through this process emits 6.6–9.3 tonnes of carbon dioxide. While carbon capture and storage (CCS) could remove a large fraction of these emissions, the overall carbon footprint of hydrogen from natural gas is difficult to assess {{As of|2021|lc=y}}, in part because of emissions (including [[Gas venting|vented]] and [[Fugitive gas emissions|fugitive]] methane) created in the production of the natural gas itself.

Electricity can be used to split water molecules, producing sustainable hydrogen provided the electricity was generated sustainably. However, this [[electrolysis]] process is currently more expensive than creating hydrogen from methane without CCS and the efficiency of energy conversion is inherently low. Hydrogen can be produced when there is a surplus of [[Variable renewable energy|variable renewable electricity]], then stored and used to generate heat or to re-generate electricity. It can be further transformed into liquid fuels such as [[green ammonia]] and [[green methanol]]. Innovation in [[Electrolysis of water|hydrogen electrolysers]] could make large-scale production of hydrogen from electricity [[Hydrogen economy#Costs|more cost-competitive]].

Hydrogen fuel can produce the intense heat required for industrial production of steel, cement, glass, and chemicals, thus contributing to the decarbonisation of industry alongside other technologies, such as [[electric arc furnace]]s for steelmaking. For steelmaking, hydrogen can function as a clean fuel and simultaneously as a low-carbon catalyst replacing coal-derived [[coke (fuel)|coke]]. Hydrogen used to decarbonise transportation is likely to find its largest applications in shipping, aviation and to a lesser extent heavy goods vehicles. For light duty vehicles including passenger cars, hydrogen is far behind other [[alternative fuel vehicle]]s, especially compared with the rate of adoption of [[battery electric vehicles]], and may not play a significant role in future.

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=== Energy usage technologies ===

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====Transport====

[[File:Hornby Street Separated Bike Lane.jpg|thumb|right|alt=Group of cyclists using a bike lane in Vancouver, Canada|[[Utility cycling]] infrastructure, such as this [[bike lane]] in [[Vancouver]], encourages sustainable transport.>]]

{{main|Sustainable transport}}

Transport accounts for 14% of global greenhouse gas emissions, but there are multiple ways to make transport more sustainable. [[Public transport]] typically emits fewer greenhouse gases per passenger than personal vehicles, since trains and buses can carry many more passengers at once. Short-distance flights can be replaced by [[high-speed rail]], which is more efficient, especially when electrified.

The [[Energy efficiency in transport|energy efficiency of cars]] has increased over time, but shifting to [[electric vehicle]]s is an important further step towards decarbonising transport and reducing air pollution. A large proportion of traffic-related air pollution consists of particulate matter from road dust and the wearing-down of tyres and brake pads. Substantially reducing pollution from these [[Non-tailpipe emissions|non-tailpipe]] sources cannot be achieved by electrification; it requires measures such as making vehicles lighter and driving them less. Light-duty cars in particular are a prime candidate for decarbonization using [[Electric battery|battery technology]]. 25% of the world's [[Carbon dioxide|{{CO2}}]] emissions still originate from the transportation sector.

Long-distance freight transport and aviation are difficult sectors to electrify with current technologies, mostly because of the weight of [[Electric vehicle battery|batteries]] needed for long-distance travel, battery recharging times, and limited battery lifespans.  Where available, freight transport by ship [[Rail freight transport|and rail]] is generally more sustainable than by air and by road. [[Hydrogen vehicles]] may be an option for larger vehicles such as lorries. Many of the techniques needed to lower emissions from shipping and aviation are still early in their development, with [[ammonia]] (produced from hydrogen) a promising candidate for shipping fuel. [[Aviation biofuel]] may be one of the better uses of bioenergy if emissions are captured and stored during manufacture of the fuel.

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====Buildings====

{{Further|Renewable heat|Green building|Zero-energy building}}

Over one-third of energy use is in buildings and their construction. To heat buildings, alternatives to burning fossil fuels and biomass include electrification through [[heat pumps]] or [[Electric resistance heater|electric heaters]], [[Geothermal heating|geothermal energy]], [[central solar heating]], reuse of [[waste heat]], and [[seasonal thermal energy storage]]. Heat pumps provide both heat and air conditioning through a single appliance. The IEA estimates heat pumps could provide over 90% of space and water heating requirements globally.

A highly efficient way to heat buildings is through [[district heating]], in which heat is generated in a centralised location and then distributed to multiple buildings through [[insulated pipe]]s. Traditionally, most district heating systems have used fossil fuels, but [[District heating#Fourth generation|modern]] and [[cold district heating]] systems are designed to use high shares of renewable energy.[[File:Aghazade mansion.jpg|thumb|alt=Building with windcatcher towers|[[Passive cooling]] features, such as these [[windcatcher]] towers in Iran, bring cool air into buildings without any use of energy.]]Cooling of buildings can be made more efficient through [[Passive solar building design|passive building design]], planning that minimises the [[urban heat island]] effect, and [[district cooling]] systems that cool multiple buildings with piped cold water. [[Air conditioning]] requires large amounts of electricity and is not always affordable for poorer households. Some air conditioning units still use [[refrigerant]]s that are greenhouse gases, as some countries have not ratified the [[Kigali Amendment]] to only use climate-friendly refrigerants.

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==== Cooking ====

{{Further|Energy poverty and cooking|}}[[File:Kookplaat inductie.JPG|thumb|alt=Electric induction oven|For cooking, [[Induction cooking|electric induction stoves]] are one of the most energy-efficient and safest options.]]In developing countries where populations suffer from [[energy poverty]], polluting fuels such as wood or animal dung are often used for cooking. Cooking with these fuels is generally unsustainable, because they release harmful smoke and because harvesting wood can lead to forest degradation. The universal adoption of clean cooking facilities, which are already ubiquitous in rich countries, would dramatically improve health and have minimal negative effects on climate. Clean cooking facilities, e.g. cooking facilities that produce less indoor soot, typically use natural gas, [[liquefied petroleum gas]] (both of which consume oxygen and produce carbon-dioxide) or electricity as the energy source; biogas systems are a promising alternative in some contexts. [[Improved cookstoves]] that burn biomass more efficiently than traditional stoves are an interim solution where transitioning to clean cooking systems is difficult.

====Industry====

Over one-third of energy use is by industry. Most of that energy is deployed in thermal processes: generating heat, drying, and [[refrigeration]]. The share of renewable energy in industry was 14.5% in 2017—mostly low-temperature heat supplied by bioenergy and electricity. The most energy-intensive activities in industry have the lowest shares of renewable energy, as they face limitations in generating heat at temperatures over {{convert|200|C|sigfig=2}}.

For some industrial processes, commercialisation of technologies that have not yet been built or operated at full scale will be needed to eliminate greenhouse gas emissions. [[Steelmaking]], for instance, is difficult to electrify because it traditionally uses [[Coke (fuel)|coke]], which is derived from coal, both to create very high-temperature heat and as an ingredient in the steel itself. The production of plastic, cement, and fertilisers also requires significant amounts of energy, with limited possibilities available to decarbonise. A switch to a [[circular economy]] would make industry more sustainable as it involves recycling more and thereby using less energy compared to investing energy to mine and refine new [[raw materials]].

==Government policies==

{{Further|Politics of climate change|Energy policy}}

| quote = "Bringing new energy technologies to market can often take several decades, but the imperative of reaching net‐zero emissions globally by 2050 means that progress has to be much faster. Experience has shown that the role of government is crucial in shortening the time needed to bring new technology to market and to diffuse it widely."

| author = [[International Energy Agency]] (2021)

=== Regulations ===

[[Environmental regulations]] have been used since the 1970s to promote more sustainable use of energy. Some governments have committed to dates for [[Coal phase-out|phasing out coal-fired power plants]] and ending new [[fossil fuel exploration]]. Governments can require that new cars produce zero emissions, or new buildings are heated by electricity instead of gas. [[Renewable portfolio standard]]s in several countries require utilities to increase the percentage of electricity they generate from renewable sources.

Governments can accelerate energy system transformation by leading the development of infrastructure such as long-distance electrical transmission lines, smart grids, and hydrogen pipelines.  In transport, appropriate infrastructure and incentives can make travel more efficient and less car-dependent. [[Urban planning]] that discourages [[Urban sprawl|sprawl]] can reduce energy use in local transport and buildings while enhancing quality of life. Government-funded research, procurement, and incentive policies have historically been critical to the development and maturation of clean energy technologies, such as solar and lithium batteries. In the IEA's scenario for a net zero-emission energy system by 2050, public funding is rapidly mobilised to bring a range of newer technologies to the demonstration phase and to encourage deployment.

[[File:MicrocityCarSharingHangzhou.jpg|thumb|alt=Photograph of a row of cars plugged into squat metal boxes under a roof| Several countries and the European Union have committed to dates for all new cars to be [[zero-emissions vehicle]]s.]]

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=== Carbon pricing ===

[[Carbon pricing]] (such as a tax on {{CO2}} emissions) gives industries and consumers an incentive to reduce emissions while letting them choose how to do so. For example, they can shift to low-emission energy sources, improve energy efficiency, or reduce their use of energy-intensive products and services. Carbon pricing has encountered strong [[Politics of climate change|political pushback]] in some jurisdictions, whereas energy-specific policies tend to be politically safer. Most studies indicate that to limit global warming to 1.5{{Nbsp}}°C, carbon pricing would need to be complemented by stringent energy-specific policies.

As of 2019, the price of carbon in most regions is too low to achieve the goals of the Paris Agreement. [[Carbon tax]]es provide a source of revenue that can be used to lower other taxes or help lower-income households afford higher energy costs. Some governments, such as the EU and the UK, are exploring the use of [[carbon border adjustments]]. These place [[tariff]]s on imports from countries with less stringent climate policies, to ensure that industries subject to internal carbon prices remain competitive.

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=== Pace ===

Countries may support renewables to create jobs. The [[International Labour Organization]] estimates that efforts to limit global warming to 2&nbsp;°C would result in net job creation in most sectors of the economy. It predicts that 24&nbsp;million new jobs would be created by 2030 in areas such as renewable electricity generation, improving energy-efficiency in buildings, and the transition to electric vehicles. Six million jobs would be lost, in sectors such as mining and fossil fuels. Governments can make the transition to sustainable energy more politically and socially feasible by ensuring a [[just transition]] for workers and regions that depend on the fossil fuel industry, to ensure they have alternative economic opportunities.

==Finance==

{{Further|Climate finance}}

[[File:20210119 Renewable energy investment - 2004- BloombergNEF.svg |thumb|upright=1.35|alt=Graph of global investment for renewable energy, electrified heat and transport, and other non-fossil-fuel energy sources |Electrified transport and renewable energy are key areas of investment for the [[renewable energy transition]].]]

Raising enough money for innovation and investment is a prerequisite for the energy transition. The IPCC estimates that to limit global warming to 1.5&nbsp;°C, US$2.4&nbsp;trillion would need to be invested in the energy system each year between 2016 and 2035. Most studies project that these costs, equivalent to 2.5% of world GDP, would be small compared to the economic and health benefits. Average annual investment in low-carbon energy technologies and energy efficiency would need to be six times more by 2050 compared to 2015. Underfunding is particularly acute in the least developed countries, which are not attractive to the private sector.

The [[United Nations Framework Convention on Climate Change]] estimates that climate financing totalled $681&nbsp;billion in 2016. Most of this is private-sector investment in renewable energy deployment, public-sector investment in sustainable transport, and private-sector investment in energy efficiency. The Paris Agreement includes a pledge of an extra $100&nbsp;billion per year from developed countries to poor countries, to do climate change mitigation and adaptation. This goal has not been met and measurement of progress has been hampered by unclear accounting rules. If energy-intensive businesses like chemicals, fertilizers, ceramics, steel, and non-ferrous metals invest significantly in R&D, its usage in industry might amount to between 5% and 20% of all energy used.

Fossil fuel funding and [[energy subsidy#Fossil fuel subsidies|subsidies]] are a significant barrier to the energy transition.Ending these could lead to a 28% reduction in global carbon emissions and a 46% reduction in air pollution deaths. Funding for clean energy has been largely unaffected by the [[COVID-19 pandemic]], and pandemic-related economic stimulus packages offer possibilities for a [[green recovery]].

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==External links==

{{二次利用|date=14 July 2025, at 05:46}}