Energy conservation

Energy conservation refers to reducing energy consumption through using less of an energy service. Energy conservation differs from efficient energy use, which refers to using less energy for a constant service. For example, driving less is an example of energy conservation. Driving the same amount with a higher mileage vehicle is an example of energy efficiency. Energy conservation and efficiency are both energy reduction techniques.

Even though energy conservation reduces energy services, it can result in increased environmental quality, national security, personal financial security and higher savings. It is at the top of the sustainable energy hierarchy. It also lowers energy costs by preventing future resource depletion.

Energy tax

Some countries employ energy or carbon taxes to motivate energy users to reduce their consumption. Carbon taxes can allow consumption to shift to nuclear power and other alternatives that carry a different set of environmental side effects and limitations. Meanwhile, taxes on all energy consumption stand to reduce energy use across the board, while reducing a broader array of environmental consequences arising from energy production. The State of California employs a tiered energy tax whereby every consumer receives a baseline energy allowance that carries a low tax. As usage increases above that baseline, the tax is increasing drastically. Such programs aim to protect poorer households while creating a larger tax burden for high energy consumers.

Hydrogen fuel

Hydrogen fuel is a zero-emission fuel when burned with oxygen (if one considers water not as an emission) or used in a contained cell also capable of 'reversing' the reaction if needed. It often uses electrochemical cells, or combustion in internal engines, to power vehicles and electric devices. It is also used in the propulsion of spacecraft and might potentially be mass-produced and commercialized for passenger vehicles and aircraft.

Hydrogen lies in the first group and first period in the periodic table, i.e. it is the first element on the periodic table, making it the lightest element. Since hydrogen gas is so light, it rises in the atmosphere and is therefore rarely found in its pure form, H₂. In a flame of pure hydrogen gas, burning in air, the hydrogen (H₂) reacts with oxygen (O₂) to form water (H₂O) and releases energy.

(If carried out in atmospheric air instead of pure oxygen (as is usually the case), hydrogen combustion may yield small amounts of nitrogen oxides, along with the water vapor.)