Energy efficiency and conservation

Main articles: Efficient energy use and Energy conservation

A spiral-type integrated compact fluorescent lamp, use has grown among North American consumers since its introduction in the mid-1990s.^[127]

Efficient energy use, sometimes simply called "energy efficiency", is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature. Installing fluorescent lights or natural skylights reduces the amount of energy required to attain the same level of illumination compared to using traditional incandescent light bulbs. Compact fluorescent lights use two-thirds less energy and may last 6 to 10 times longer than incandescent lights.^[128]

Energy efficiency has proved to be a cost-effective strategy for building economies without necessarily growing energy consumption. For example, the state of California began implementing energy-efficiency measures in the mid-1970s, including building code and appliance standards with strict efficiency requirements. During the following years, California's energy consumption has remained approximately flat on a per capita basis while national U.S. consumption doubled. As part of its strategy, California implemented a "loading order" for new energy resources that puts energy efficiency first, renewable electricity supplies second, and new fossil-fired power plants last.^[129]

Energy conservation is broader than energy efficiency in that it encompasses using less energy to achieve a lesser energy service, for example through behavioural change, as well as encompassing energy efficiency. Examples of conservation without efficiency improvements would be heating a room less in winter, driving less, or working in a less brightly lit room. As with other definitions, the boundary between efficient energy use and energy conservation can be fuzzy, but both are important in environmental and economic terms. This is especially the case when actions are directed at the saving of fossil fuels.^[130]

Reducing energy use is seen as a key solution to the problem of reducing greenhouse gas emissions. According to the International Energy Agency, improved energy efficiency in buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help control global emissions of greenhouse gases.^[131]

Demand side fuel switching[edit]

Fuel switching on the demand side refers to changing the type of fuel used to satisfy a need for an energy service. In order to meet deep decarbonization goals, like the 80% reduction by 2050 goal being discussed in California and the European Union,^[132][133] combustion of fossil fuels for space and water heating in buildings will need to be reduced. Energy efficiency alone may not be sufficient to meet these goals, which means that the fuel used on the demand side will need to have lower carbon emissions.^[134][135] There are various ways in which this could happen, and different strategies will likely make sense in different locations. As the low-carbon renewable generation makes up a greater fraction of the generation mix, replacing gas or oil furnaces and water heaters with electric ones will have greater climate benefit. In some areas of the country that use mostly renewables, hydropower, or natural gas, this is already the case. While the system efficiency of a gas furnace may be higher than an electric resistance heater, electric heat pumps that use electricity from an efficient natural gas generator already have lower emissions per unit of heat delivered in suitable climates. This possible because of the highcoefficient of performance of heat pumps.

The economics of switching from fossil fuels to electricity for space and water heating will depend on the relative prices of each fuel and the relative prices of the equipment. The EIA Annual Energy Outlook 2014 suggests that gas prices will rise faster than electricity prices which will encourage electrification in the coming decades.^[136] Electrifying heating loads may also provide a flexible resource that can participate in demand response. Since thermostatically controlled loads have inherent energy storage, electrification of heating could provide a valuable resource to integrate variable renewable resources into the grid.

Alternatives to electrification, include decarbonizing pipeline gas through power to gas, biogas, or other carbon neutral fuels. A 2015 study by Energy+Environmental Economics shows that a hybrid approach of decarbonizing pipeline gas, electrification, and energy efficiency can meet carbon reduction goals at a similar cost as only electrification and energy efficiency in Southern California.^[137]

Sinks and negative emissions[edit]

Main articles: Carbon sink and Negative carbon dioxide emission

A carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period, such as a growing forest. Anegative carbon dioxide emission on the other hand is a permanent removal of carbon dioxide out of the atmosphere, such as directly capturing carbon dioxide in the atmosphere and storing it in geologic formations underground.

The Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC) notes that one third of humankind’s annual emissions of CO₂ are absorbed by the oceans. The oceans act as a carbon sink, that is, a reservoir that accumulates and stores carbon via its physicochemical and biological processes.^[138] Unfortunately, this "vital service comes with the cost of ocean acidification". The ecological effects of ocean acidification are still largely unknown. Research so far has focussed on how acidification lowers pH and the level of carbonate ions available for calcifying organisms to form their shells. These organisms include plankton species that contribute to the foundation of the Southern Ocean food web. However acidification may impact on a broad range of other physiological and ecological processes, such as fish respiration, larval development and changes in the solubility of both nutrients and toxins.^[139] According to the CSIRO ^[140] the Southern Ocean is absorbing increasing amounts of carbon dioxide, with potentially significant impacts on marine life.^[141]