Remember Tata Motors’ plan for a car that ran off of compressed air? There was a lot of talk about this back in 2009. They planned to bring such a vehicle, based on Motor Development International’s (MDI) technology, to market by 2011. But there were many technical problems, with some potential show stoppers. The compressed air car was not seen as terribly efficient because of various conversion losses, using electric or gas-powered motors to compress the air.
But what if the compressed air could be acquired without and electric or gas motor?
I have always wondered if this might be an ideal use of wind turbines. Electrical energy from wind turbines, like electric energy from photovoltaics, suffers from the lack of a practical storage method. Let’s say you want to run your electric car off of energy from a wind turbine. Kinetic energy of the wind is converted to mechanical (kinetic) energy of the turbine, which is converted to electrical energy in the generator (suffering from grid losses as it is delivered to your charging station), which is converted to chemical energy in your battery, which then converted back into electrical energy for the magnetic coils of the motor, which is converted back into mechanical energy to turn your wheels.
What if the mechanical energy of the turbine instead used to compress air or another gas? A compressed air car pulls up to the storage tank of the turbine compressed air, fills up and drives away. No generator, no transmission lines, no battery and no electric motor conversions involved. This would take advantage of the best features of wind turbines and compressed air cars, eliminating some of the losses that make each of them less efficient.
Fluid compressing wind turbine system
I started thinking about this again today when reading about a proposal by Winhyne Energy Group to build a turbine system in Wyoming in which the turbine would compress a fluid instead of turning a generator. The compressed fluid would them either turn a generator, or be stored to power the generator when the wind was not available.
Here is a schematic of a single turbine/single generator system…
Couldn’t something similar be done to compress a gas?
New life for compressed air vehicles
While Tata Motors’ bold claims of bringing a compressed air vehicle to market by 2011 fizzled, the hope is not dead. Last year Tata said it was done with its first phase of development and it “ has now been successfully completed with the compressed air engine concept having been demonstrated in two Tata Motors vehicles” and that they were now in the second phase and and that MDI and Tata “are working together to complete detailed development of the technology and required technical processes to industrialize a market ready product application over the coming years.”
Note that the recently announced Peugeot compressed air car, to be marketed by 2016, is not really the same thing. This is a hybrid system has a gasoline or diesel engine and does not have an air tank that you “fill up” with compressed air. Rather, is captures braking energy to compress air, which can then be used for acceleration. This concept offers great fuel saving potential in cities where frequent stop and start driving causes large energy losses to braking.