Time for Negative-Emission Vehicles

Are you tired of the lunacy called Zero Emission Vehicles. The constant back-and-forth between EV-enthusiasts, ICE advocates, and everyone in between. The misnomer is, surprisingly, an invention of engine-community. Granted, the progress in emission reduction has been nothing short of miraculous, but the OEMs went a little overboard in their claims of emission reduction, and labelled some vehicles as NZEV. Near-Zero is a convenient term though. Everything and nothing can be Near-Zero. Is 100 near zero? Depends if you are asking relative to 101 or 100^10. In this context, depends if you are talking with respect to Euro I or the previous Euro 5. I noticed several purely-ICE vehicles flaunting ‘NZEV’ (for Near-Zero Emission Vehicles) badge on their trunk door. It was probably granted because the criteria emissions from tailpipe were pretty low in the test-environment. Real-world could be telling a different story.

But let’s rewind a bit to where it all began - the city of Los Angeles (a city with a peculiar geography that didn’t allow much of the automotive pollutants to disperse as well as other places across the globe) started the regulations, and they have only gotten stricter since. We’ve made great progress and engine-driven vehicles are far from being the biggest source of criteria pollutants in most parts of the world (provided the legislations are enforced duly).

Now here is where things get really interesting. NZEV referred only to tailpipe emissions so, by that logic, cars not running on hydrocarbons (Battery Electric or Fuel Cell Vehicles) are ZEV – Zero Emission Vehicles. These vehicles emitted nothing from tailpipe that was considered criteria pollutant. While the progression from Near-Zero to Zero makes sense, this is when the swords were out, cause it’s a rather new technology using the old nomenclature, that was supposed to give an edge to ICE.

Is it okay to call BEV and FCEVs as Zero Emission Vehicles? In my opinion, it is as wrong as calling those ICE vehicles Near Zero Emission Vehicles, which translates to very wrong. I think I have some knowledge of lifecycle assessment, having worked on half a dozen LCA projects till now, so I also understand the nitty-gritties of the issue. I understand that zero-emission vehicles are not possible. It will violate the laws of thermodynamics, if we made one. But operationally, from tailpipe, it is possible.

So, if zero emissions are a stretch, what about negative emissions? Enter the contenders. I remember seeing Honda Motors present their next-gen engines emit hydrocarbons lower than the surrounding air. So essentially the car is cleaning the air as it drives. #mindBlown

But then that’s the limit of negative emissions from ICE vehicles, and its only hydrocarbon emissions. Engine folks (like me) understand it quite well that many emissions have trade-offs, for example, NOx and particulate matter don’t usually go down together. While research continues on mitigating these trade-offs, proportional reductions in all emissions (below ambient levels) will not be easy. Negative emission (for all tailpipe pollutants) is impossible.

The real villain today is Carbon Dioxide. How can we achieve negative CO2 emissions from ICE vehicles. ICE burning hydrocarbons will emit CO2 (of course), so tailpipe negative emissions is out of question. What if we could offset all that tailpipe CO2 emissions with even more CO2 sequestration. I know I am entering fantasy territory now, but let’s give it a chance. Here's a hypothetical scenario:

• Biomass grows, absorbing CO2 from the atmosphere.
• Biomass is sustainably harvested and converted to ethanol using a process that captures the CO2 emissions.
• The captured CO2 is stored underground or utilized in other industrial processes.
• The produced ethanol replaces a fossil fuel like gasoline.

I can point to countless publications that will suggest that its not possible to achieve negative emissions. But theoretically, we could.

Now, how about FCEVs? Surely, the carbon intensity of hydrogen produced today is off the charts (ranges from 10-30 kgCO2/kgH2). So, running anything on hydrogen is a climate-crime. But again, lets see if there are any theoretical possibilities:

• Cow burps and farts are captured giving us renewable Methane
• That renewable methane is used to make hydrogen and the associated CO2 is captured.
• The captured CO2 is stored underground or utilized in other industrial processes.

The oft-talked about ideal scenario of producing hydrogen from (otherwise) curtailed renewable electricity can only be zero emissions, at best.

Amidst all this fiction, I see a glimmer of possibility of negative emissions with electric vehicles though, that too in very near future. There are geographies which may be blessed with firm low carbon energy, which are dispatchable, but most are not. The success of solar power has been extremely geography-agnostic, and it is not going to stop either. We are already reaching negative duck curves during noon on few occasions, and the frequency of these events will become commonplace in times to come. What is closer (in time) is the displacement of natural gas power during peak load operations with energy storage (in form of 4-hr batteries). So, batteries replacing natural gas peaker plants can reduce the emissions significantly in evening. If you look at CAISO data for example, it seems like the emissions don’t peak during peak load times (evenings), rather during night time, a trend that will get more pronounced in future as per NREL’s Cambium model.

This is likely due to 4-hr batteries being ineffective later than sunset time. Most people with rooftop solars and Tesla powerwall are already doing these bidirectional transactions (charging from rooftop solar and discharging to grid during peak hours). Below is a good comparison for prospective buyers:

I think it is interesting that you can get a battery + a car, cheaper than buying the battery alone. If you have a battery connected to the grid in a bidirectional transaction (feeding the grid in evening), your car is offsetting a lot of natural gas (and often times coal) burning.

I guess you understand the idea now. With vehicle-to-grid your zero-emission electric car is actually helping reduce the emissions, by avoiding CO2 emissions of a fossil-powered plant. This a pretty near (or current) scenario with negative emissions. Also, this scenario also helps us differentiate between fool-cell vehicles and electric vehicles. The fictional scenario means you charge your vehicle on solar power when in office (abundant solar periods), and help the grid offset peaker plant emissions in evening. Of course, we still need a firm renewable energy source for baseload, that can be wind or nuclear or geothermal. Oops, am I entering fantasy territory again?

So, the next time you hear someone talk about "Zero Emission Vehicles," just smile and nod, knowing that the future might just be filled with Negative Emission Vehicles instead. After all, a little optimism never hurt anyone – except maybe the fossil fuel industry.

PS: I do not believe that there are any zero emission vehicles, so this is merely extending the already ludicrous nomenclature. I don’t want anyone to adopt these names.