Energy density

（英文的维基百科真的比中文的维基百科强很多，而中文的维基百科又比度娘强很多！）

小编有些单词不认识已作出标注。

Introduction to energy density

There are many different types of energy stored in materials, and it takes a particular type of reaction to release each type of energy. In order of the typical magnitude of the energy released, these types of reactions are: nuclear, chemical, electrochemical, and electrical.

Chemical reactions are used by animals to derive energy from food, and by automobiles to derive energy from gasoline. Electrochemical reactions are used by most mobile devices such as laptop computers and mobile phones to release the energy from batteries.

Energy densities of common energy storage materials

The following is a list of the thermal energy densities of commonly used or well-known energy storage materials; it doesn't include uncommon or experimental materials.

Note that this list does not consider the mass of reactants commonly available such as the oxygen required for combustion（燃烧） or the energy efficiency in use.

The following unit conversions（单位转换） may be helpful when considering the data in the table: 1 MJ≈ 0.28 kWh≈ 0.37HPh.

Energy capacities of common storage forms

Automotive lead-acid battery (汽车铅酸电池) 0.17 MJ/kg

Alkaline AA battery (AA碱性电池) 0.616 MJ/kg

Lithium-ion battery (锂离子电池) 0.645 MJ/kg

Lithium battery (non-rechargeable) 1.8 MJ/kg

Natural gas 53.6 MJ/kg