In pollution abatement, the best available technology (or BAT) is the technology approved for limiting pollutant discharges with regard to an abatement strategy. Similar terms are best available techniques, best practicable means or best practicable environmental option. BAT is a moving target on practices, since developing societal values and advancing techniques may change what is currently regarded as "reasonably achievable", "best practicable" and "best available".
A literal understanding will connect it with a "spare no expense" doctrine which prescribes the acquisition of the best state of the art technology available, without regard for traditional cost-benefit analysis. In practical use, the cost aspect is also taken into account. [See also discussions on the topic of the precautionary principle which, along with considerations of best available technologies and cost-benefit analyses, is also involved in discussions leading to formulation of environmental policies and regulations (or opposition to same).]
Best practicable means was used for the first time in UK national primary legislation in section 5 of the Salmon Fishery Act 1861 and another early use was found in the Alkali Act Amendment Act 1874, but before that appeared in the Leeds Act of 1848.
The BAT concept was first time used in the 1992 OSPAR Convention for the protection of the marine environment of the North-East Atlantic for all types of industrial installations.
Some doctrine deem it already acquired the status of customary law.
Best available techniques not entailing excessive costs (BATNEEC), sometimes referred to as best available technology, was introduced in 1984 with Directive 84/360/EEC and applied to air pollution emissions from large industrial installations.
In 1996, Directive 84/360/EEC was superseded by the Integrated pollution prevention and control directive (IPPC), 96/61/EC, which applied the framework concept of Best Available Techniques (BAT) to the integrated control of pollution to the three media air, water and soil. The concept is also part of the directive's recast in 2008 (2008/1/EC) and its successor directive, the Industrial Emissions Directive 2010/75/EU published in 2010.
According to article 15(2) of the Industrial Emissions Directive, emission limit values and the equivalent parameters and technical measures in permits shall be based on the best available techniques, without prescribing the use of any technique or specific technology.
The directive includes a definition of best available techniques in article 3(10):
"best available techniques" means the most effective and advanced stage in the development of activities and their methods of operation which indicates the practical suitability of particular techniques for providing the basis for emission limit values and other permit conditions designed to prevent and, where that is not practicable, to reduce emissions and the impact on the environment as a whole:
- - "techniques" includes both the technology used and the way in which the installation is designed, built, maintained, operated and decommissioned;
- - "available" means those developed on a scale which allows implementation in the relevant industrial sector, under economically and technically viable conditions, taking into consideration the costs and advantages, whether or not the techniques are used or produced inside the Member State in question, as long as they are reasonably accessible to the operator;
- - "best" means most effective in achieving a high general level of protection of the environment as a whole.
BAT for a given industrial sector are described in BAT reference documents (BREFs) as defined in article 3(11) of the Industrial Emissions Directive. BREFs are the result of an exchange of information between European Union Member States, the industries concerned, non-governmental organisations promoting environmental protection and the European Commission pursuant to article 13 of the directive. This exchange of information is often called the Sevilla process because it is steered by the Institute for Prospective Technological Studies of the European Commissions' Joint Research Centre, which is based in Seville. The process is described in detail in Commission Implementing Decision 2012/119/EU. The most important chapter of the BREFs, the BAT conclusions, are published as implementing decisions of the European Commission in the Official Journal of the European Union. According to article 14(3) of the Industrial Emissions Directive, the BAT conclusions shall be the reference for setting permit conditions of large industrial installations.
In the development of the effluent standards, the BAT concept is a "model" technology rather than a specific regulatory requirement. The U.S. Environmental Protection Agency (EPA) identifies a particular model technology for an industry, and then writes a regulatory performance standard based on the model. The performance standard is typically expressed as a numeric effluent limit measured at the discharge point. The industrial facility may use any technology that meets the performance standard.
A related CWA provision for cooling water intake structures requires standards based on "best technology available."
The concept of BAT is also used in a number of international conventions such as the Minamata Convention on Mercury, the Stockholm Convention on Persistent Organic Pollutants, or the OSPAR Convention for the protection of the marine environment of the North-East Atlantic.