Internal combustion engines are likely to remain in widespread use for some time yet, but it’s possible that we may be bidding adieu to that most iconic of engine parts, the spark plug. Researchers from Japan’s National Institutes of Natural Sciences (NINS) are creating laser igniters that could one day replace spark plugs in automobile engines. Not only would these lasers allow for better performance and fuel economy, but cars using them would also create less harmful emissions.
Located at the top of each engine cylinder, spark plugs send a high-voltage electrical spark across a gap between their two metal electrodes. That spark ignites the compressed air-fuel mixture in the cylinder, causing a controlled mini-explosion that pushes the piston down.
One byproduct of the process are toxic nitrogen oxides (NOx), which pollute the air causing smog and acid rain. Engines would produce less NOx if they burnt more air and less fuel, but they would require the plugs to produce higher-energy sparks in order to do so. While this is technically possible, the voltages involved would burn out the electrodes quite quickly. Laser igniters on the other hand, could ignite leaner mixtures without self-destructing because they don’t have electrodes.