User:Clayoquot/CCM

Co-Benefits
Mitigation measures may have many health co-benefits – potential measures can not only mitigate future health impacts from climate change but also improve health directly. Globally the cost of limiting warming to 2 °C is less than the value of the extra years of life due to cleaner air - and in India and China much less. Air quality improvement is a near-term benefit among the many societal benefits from climate change mitigation, including substantial health benefits. Studies suggest that demand-side climate change mitigation solutions have largely beneficial effects on 18 constituents of well-being.

Energy storage
Wind energy and photovoltaics can deliver large amounts of electric energy but not at any time and place. One approach is the conversation into storable forms of energy. This generally leads to losses in efficiency.

For storage requirements up to a few days, pumped hydro (PHES), compressed air (CAES) and Li-on batteries are most cost effective depending on charging rhythm. For 2040, a more significant role for Li-on and hydrogen is projected. Li-on batteries are widely used in battery storage power stations and are starting to be used in vehicle-to-grid storage. They provide a sufficient round-trip efficiency of 75–90 %. Their production can cause environmental problems. Levelized costs for battery storage have drastically fallen.

Hydrogen may be useful for seasonal energy storage. Thermal energy in the conversion process can be used for district heating. The concept of solar hydrogen is discussed for remote desert projects where grid connections to demand centers are not available. Because it has more energy per unit volume sometimes it may be better to use hydrogen in ammonia.

Energy grids
Long-distance power lines help to minimize storage requirements. A continental transmission network can smoothen local variations of wind energy. With a global grid, even photovoltaics could be available all day and night. The strongest high-voltage direct current (HVDC) connections are quoted with losses of only 1.6% per 1000 km with a clear advantage compared to alternating current (AC) grids. HVDC is currently only used for point-to-point connections. Meshed HVDC grids may be used to connect offshore wind in future.

A super grid in the US in combination with renewable energy could reduce GHG emissions by 80%.

Electricity demand management
Instead of expanding grids and storage for more power, electricity demand can be adjusted on the consumer side. This can flatten demand peaks. Traditionally, the energy system has treated consumer demand as fixed. Instead, data systems can combine with advanced software to manage demand and respond to energy market prices.

Time of use tariffs are a common way to motivate electricity users to reduce their peak load consumption. On a household level, charging electric vehicles or running heat pumps combined with hot water storage when wind or sun energy are available reduces electricity costs.

Demand response devices can receive all sorts of messages from the grid. The message could be a request to use a low power mode, to shut off entirely during a sudden failure on the grid, or notifications about the current and expected prices for power. This allows electric cars to recharge at the least expensive rates independent of the time of day. Vehicle-to-grid uses a car's battery to supply the grid temporarily.

Buildings
The buildings sector accounts for 23% of global energy-related emissions. About half of the energy is used for space and water heating. Building insulation can reduce the primary energy demand significantly. Efficient electric heating and cooling loads may also provide a flexible resource that can participate in demand response to integrate variable renewable resources into the grid. Solar water heating uses the thermal energy directly. Sufficiency measures include moving to smaller houses when the needs of households change, mixed use of spaces and the collective use of devices. New buildings can be constructed using passive solar building design, low-energy building, or zero-energy building techniques.In addition, it is possible to design buildings that are more energy-efficient to cool by using lighter-coloured, more reflective materials in the development of urban areas.

Heat pumps
Heat pumps are an example of electrified heating with high efficiency. A modern heat pump typically produces around three to five times more thermal energy than electrical energy consumed, depending on the coefficient of performance and the outside temperature. It uses an electrically driven compressor that extracts heat energy from outdoor air or ground sources and moves that heat to the space to be warmed. In the summer months, the cycle can be reversed for air conditioning.

Cooling
Refrigeration and air conditioning account for about 10% of global emissions caused by fossil fuel-based energy production and the use of fluorinated gases. Alternative cooling systems, such as passive cooling building design and installing passive daytime radiative cooling surfaces, can reduce air conditioning use. Suburbs and cities in hot and arid climates can significantly reduce energy consumption from cooling with daytime radiative cooling.

The energy consumption for cooling is expected to rise significantly due to increasing heat and availability of devices in poorer countries. Of the 2.8 billion people living in the hottest parts of the world, only 8% currently have air conditioners, compared with 90% of people in the US and Japan. By combining energy efficiency improvements with the transition away from super-polluting refrigerants, the world could avoid cumulative greenhouse gas emissions of up to 210–460 Gte over the next four decades. A shift to renewable energy in the cooling sector comes with two advantages: Solar energy production with mid-day peaks corresponds with the load required for cooling. Additionally, cooling has a large potential for load management in the electric grid.

Energy in the form of transport
Transportation emissions account for 15% of emissions worldwide. Increasing the use of public transport, low-carbon freight transport and cycling are important components of transport decarbonization.

Electric vehicles and environmentally friendly rail help to reduce the consumption of fossil fuels. In most cases, electric trains are more efficient than air transport and truck transport. Other efficiency means include improved public transport, smart mobility, carsharing and electric hybrids. Fossil-fuel powered passenger cars can be converted to electric propulsion. The production of alternative fuel without GHG emissions is only possible with high conversion losses. Furthermore, moving away from a car-dominated transport system towards low-carbon advanced public transport system is important.

Heavyweight, large personal vehicles (such as cars) require a lot of energy to move and take up much urban space. Several alternatives modes of transport are available to replace these. The European Union has made smart mobility part of its European Green Deal and in smart cities, smart mobility is also important.

Electric vehicles
Between a quarter and three-quarters of cars on the road by 2050 are forecast to be electric vehicles. EVs use 38 megajoules per 100 km in comparison to 142 megajoules per 100 km for ICE cars. Hydrogen can be a solution for long-distance transport by trucks and hydrogen-powered ships where batteries alone are too heavy.

GHG emissions depend on the amount of green energy being used for battery or fuel cell production and charging. In a system mainly based on electricity from fossil fuels, emissions of electric vehicles can even exceed those of diesel combustion.

Shipping
In the shipping industry, the use of liquefied natural gas (LNG) as a marine bunker fuel is driven by emissions regulations. Ship operators have to switch from heavy fuel oil to more expensive oil-based fuels, implement costly flue gas treatment technologies or switch to LNG engines. Methane slip, when gas leaks unburned through the engine, lowers the advantages of LNG. Maersk, the largest container shipping line and vessel operator in the world, warns of stranded assets when investing into transitional fuels like LNG. The company lists green ammonia as one of the preferred fuel types of the future and has announced the first carbon-neutral vessel on the water by 2023, running on carbon-neutral methanol.

Hybrid and all electric ferries are suitable for short distances. Norway's goal is an all electric fleet by 2025. The E-ferry Ellen, which was developed in an EU-backed project, is in operation in Denmark.

Air travel


Jet airliners contribute to climate change by emitting carbon dioxide, the best understood greenhouse gas, and, with less scientific understanding, nitrogen oxides, contrails and particulates. Their radiative forcing is estimated at 1.3–1.4 that of alone, excluding induced cirrus cloud with a very low level of scientific understanding. In 2018, global commercial operations generated 2.4% of all emissions.

While the aviation industry has become more fuel efficient, overall emissions have risen as the volume of air travel has increased. By 2020, aviation emissions were 70% higher than in 2005 and they could grow by 300% by 2050.

Aviation's environmental footprint can be reduced by better fuel economy in aircraft, and by optimising flight routes to lower non- effects on climate from, particulates or contrails. Aviation biofuel, emissions trading and carbon offsetting, part of the ICAO's CORSIA, can lower emissions. Aviation usage can be lowered by short-haul flight bans, train connections, personal choices and taxation on flights. Fuel-powered aircraft may be replaced by hybrid electric aircraft and electric aircraft or by hydrogen-powered aircraft.

In aviation, current 180 Mt of emissions (11% of emissions in transport) are expected to rise in most projections, at least until 2040. Aviation biofuel and hydrogen can only cover a small proportion of flights in the coming years. The market entry for hybrid-driven aircraft on regional scheduled flights is projected after 2030, for battery-powered aircraft after 2035. In October 2016, the 191 nations of the ICAO established the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), requiring operators to purchase carbon offsets to cover their emissions above 2020 levels, starting from 2021. This is voluntary until 2027.