If you haven’t already, be sure to read Part 1 to see where my data comes from, what my assumptions are, and how I calculated everything. There’s even a spreadsheet you can use to do your own calculations if you think I’m wrong or want to plug in different numbers.
With that having been said, let’s talk about what the numbers look like when you charge at home with rooftop solar instead of charging from the grid! This is one of the things the writers at The Drive didn’t do, and probably what inspired me to go through all the trouble of collecting my own data and making charts.
As you can see, charging with renewables makes a big difference compared to grid charging. Here’s that grid-based chart again so you can see them on the same screen:
To be clear, I wasn’t lazy and I didn’t assume that rooftop solar has zero emissions. I used numbers from NREL for average emissions per kWh so we’d put the grid and solar on a totally level playing field.
As you can see, charging with solar really flattens the lines down for the BEV and PHEV. Solar panel production, transport, installation, removal, and recycling aren’t environmentally free, but they’re still very small compared to grid power. This drops your per-mile CO2 down significantly, making the BEV and PHEV a much better environmental deal.
This really proves the importance of not just getting people to drive electric, but to clean up the grid. Not everybody can get home solar, so getting the grid to be as clean as home solar should also be a top priority. However, getting people into EVs is essential even on today’s grid because there’s an opportunity to make those environmental gains with EVs while gas-powered vehicles can’t get cleaner as the grid improves.
Nothing illustrates this better than the widened gap between the PHEV and the EV when both are charged on home solar. The PHEV’s part-time gas-burning habit stands out in much starker contrast than when it has to stand up against grid power. Running on clean electricity also pushes the breakeven point between BEV and PHEV back below 100,000 miles, making it a much cleaner choice.
That having been said, either choice is still far below the emissions of the hybrid. So, if somebody just didn’t want the BEV truck because of range concerns, I’d much rather see them on the yellow line than the blue line.
Adding the V8 F-150 into this mix really shows us the sharp contrast that clean power makes. It’s not visible on the chart, but the final 300,000 mile figure for the V8 (assuming it survives to 300,000) is 190,220 kg of CO2, while the solar-powered EV truck is barely breaking 50,000 kg and probably still has a lot of useful life left in it.
We can see that with renewable energy that the hybrid really starts to be closer to gas than it is to electric. The benefits to the hybrid are real, but they’re limited and can’t get cleaner with the grid or switch to solar at home in the short term. And, these are just the environmental benefits. If I were to take the time to use average numbers to create charts for the overall cost (something I may do at some point), the difference would be even starker.
This Still Assumes 10% Gas Driving For The PHEV
As I pointed out in Part 2, the PHEV’s ability to almost be as good as the BEV depends on the driver. With no perverse incentives, the extra cost of the PHEV over the hybrid is something only people looking to save by plugging in would want to bear. If we add incentives into the mix, people might buy them to get access to carpool lanes, tax credits, etc. So, we need to be really careful how we design those incentives.
The PHEV Still May Be Better For The Next Few Years
I think everybody will agree that we need to get as many people onto those flatter lines as possible. Putting a relatively small number of wealthy people into big trucks with big batteries and putting solar on their homes is great, but we have to remember that we’ll need to open up a lot more mines and refining facilities to get battery cell production up to where it needs to be for everybody to get an EV. If we can put four people on the yellow line or one person on the red line, it’s kind of a no-brainer at this point.
For people who would only consider the yellow, blue, or green line, we’d definitely rather put them on the yellow line if that’s the only thing they’ll consider.
What About Truly Bad BEVs Like The Hummer EV?
To really put PHEV in perspective, I decided to add the Hummer EV to the chart, and give it the same solar charging (90% of the time) that the Lightning and theoretical F-150 PHEV would get. As you can see, the 212.7 kWh battery pack’s production emissions, along with the extreme weight of the vehicle itself, drive total production emissions up to as much as the 300,000 mile lifetime emissions of the Lightning with the 131 kWh battery pack. Ouch!
The emissions associated with the Hummer EV are so bad that that they can’t even beat a PHEV truck that spends ten percent of its time burning gas, and there’s probably room to burn gas 20% of the time and still emit less than the Hummer EV powered by solar.
So, the scenario we desperately need to avoid at all costs is using up the battery supply on vehicles like the Hummer EV and Tri-motor Cybertruck with a 200 kWh battery. The production emissions are so high and they take up so many battery cells, that we’d minimize the benefits of EVs while keeping more efficient and affordable EVs priced out of reach of the people who want to buy them. The end result of doing something like that could be worse than doing nothing at all.
All chart images provided by Jennifer Sensiba.
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