Capturing exhaust heat to generate power
Helping transportation, which is a major contributor to carbon emissions, become more energy efficient is a long-term aim for MicroPower
Approximately a third of the energy you put into a standard automobile in the form of fuel is wasted as heat from the exhaust, and most other traditional forms of transportation are equally wasteful.
Capturing some of this waste heat and converting it into electricity for on-board use by using thermoelectric devices has long been seen as viable path backed by governments and vehicle and engine manufacturers worldwide.
However, the barriers to entry into these markets are high. The regulatory requirements are significant while the economics of deploying thermoelectric technology in settings where the devices will often not be in use presents another hurdle to be overcome.
The US DoE, EU and most major auto manufacturers began pursuing the use of thermoelectrics to replace belt-driven alternators in the mid-2000s, targeting a 10% increase in fuel efficiency predicated on the development 20% efficient thermoelectric units. Progress was significantly hampered by the fact that the thermoelectric devices at the time delivered efficiencies far below the targeted 20%.
The automotive industry’s pursuit of thermoelectrics may not have been based purely on financial considerations, as the economics are not necessarily compelling for a significant portion of the market unless far greater efficiencies can be obtained, and the price can be reduced below $1/watt. Consequently, it is not area in which we are currently focusing our resources, particularly with the advent of electric vehicles.
Manufacturers of heavy trucks or works vehicles have also pursued the use of thermoelectrics as a means of achieving greater energy efficiency and increased reliability. Of course, trucks only make up a fraction of the overall automotive market (approximately 4%), but they travel far more miles annually than ordinary passenger vehicles, often covering 80,000 miles in a single year.
Clearly, one of the key reasons that the economic case for automotive applications does not appear compelling is that most people are not driving their car for the vast majority of the time. However, employing the same economic model to commercial trucks presents a far more appealing proposition due to the fact trucks are driven significantly more, and are less fuel-efficient.
As in the auto industry, MicroPower thermoelectric generators capturing waste heat produced by the main engine could be used to generate electricity. Though fuel economy and reduced emissions are obvious benefits, the primary driver for the implementation of waste heat recovery systems in the aviation industry is the desire to significantly increase on-board power capabilities without needing to undertake a major engine redesign.
Most of the transportation sectors share common waste heat technologies (reciprocating engines with exhaust pipes or steam systems with cooling pipes) and will share common thermoelectric solutions. Jet engine technology along with mission critical safety will require a careful and lengthy development process.