attaching an air compressor or hydraulic pump to a wind turbine or using river, tidal, wave hydropower turbine with only a conversion from mechanical to pneumatic energy, eliminating electricity from the loop which gives higher efficiency overall. Also there is the possibility of using thermal energy with a parabolic or fresnel lens solar concentrator to power a thermal stirling engine to move the compressor or pump, as solar stirling is more efficient than solar steam and Photovoltaic. (see also Solar-powered Stirling engine) Emission output Since the compressed air is filtered to protect the compressor machinery, the air discharged has less suspended dust in it, though there may be carry-over of lubricants used in the compressor or engine. This can be mitigated by using oil free air compressors. Resource consumption The recent developments of composite pressure vessels and pneumatic components means that compressed air vehicles can be part of the circular industry with biobased or recycled components. Also by cutting electric energy from the loop there is no need for electric grid and the metals used like cooper, iron in magnets, etc. History Compressed air has been used since the 19th century to power mine locomotives and trams in cities such as Paris (via a central, city-level, compressed air energy distribution system), and was previously the basis of naval torpedo propulsion. During the construction of the Gotthardbahn from 1872 to 1882, pneumatic locomotives were used in the construction of the Gotthard Rail Tunnel and other tunnels of the Gotthardbahn. In 1903, the Liquid Air Company located in London, United Kingdom, manufactured a number of compressed-air and liquified-air cars. The major problem with these cars and all compressed-air cars is the lack of torque produced by the "engines" and the cost of compressing the air. Since 2010, several companies have started to develop compressed air cars, including hybrid types that also include a petrol driven engine; none has been released to the public, or have been tested by third parties. Advantages Energy efficiency of the energy source, by using wind turbines to compressors or pumps there is a single conversion of mechanical to pneumatic or hydraulic energy, and by powering the compressor with stirling engine with a parabolic or fresnel lens solar concentrator there's thermal energy to mechanical energy conversion, also by using a phase change material in the heat exchanger heated with concentrated solar power there is only solar thermal energy