Quick Truck Study: FCEV vs BEV lifecycle CO2 emissions - PART 2

A few days ago I published my study Quick Truck Study: FCEV vs BEV lifecycle CO2 emissions on comparing BEV truck’s CO2 to FCEV trucks CO2, which has received a lot of attention. It found that the CO2 output over an average Class 8 truck mileage and life span (65,000 miles per year for 10 years) for BEV and FCEV trucks were very similar in a low emissions 40g/kWh grid. 

One of the comments I received, from David Wenger, was that the Nikola H2 usage assumption may be a bit low.

As I was working through the cost and use case implications for my next study of heavy duty FCEV vs BEV, I found that Nikola’s lease numbers weren’t adding up to the 4.6kg/100km for H2 usage (a figure I thought to be optimistic). It turns out that 4.6kg/100km was an early Nikola assumption, and the revised number used in Nikola’s Prospectus is 7.5 miles /kg, or 8.33kg /100km, an 81% increase. Obviously, this will have a significant impact on the final results.

So, Part 2 of this study is a revision to correct an earlier mistake, fall on my sword as it were. All other assumptions and points made in the earlier study remain the same.

Here, we re-run the numbers again, using 8.33kg per 100km for Nikola.

SCENARIO 1 - Average km, very low electricity CO2

STEP 1 – USAGE EMISSIONS

Energy usage

Tesla - <125 kWh/100km (we'll use 125 kWh here)

Nikola – 8.33kg H2/100km (1kg H2 takes 61.2kWh) or 509.8kWh/100km (based on 7.5 miles per kg)

Assumed CO2 output per year (40g/kWh)

Tesla – (1.25kWh/km x 100,000)x 0.04kg CO2 = 5,000kg CO2 per year

Nikola – (5.098kWh/km x 100,000)x 0.04kg CO2 = 20,392kg CO2 per year

STEP 2 - EMBODIED EMISSIONS

Tesla Semi 500 mile - 1,000kWh battery (my assumption) – 83,000kg CO2

(Tesla Semi 300 mile - 600kW battery (my assumption) – 49,800kg CO2)

Nikola – 250kWh battery (Nikola staff) – 20,780kg CO2

STEP 3 - TOTAL – 10 year life-cycle (usage emissions + embodied emissions)

Tesla – 83,000kg embodied + (5,000kg x 10 years) = 133,000kg CO2

Nikola – 20,780kg embodies + (20,392kg x 10 years) = 224,698kg CO2

RESULT - Nikola One/Two has 69% HIGHER CO2 emissions than Tesla Semi at 40g CO2/kwh and 100,000km per year for 10 years in their lifecycle.

SCENARIO 2 - High km, very low electricity CO2

This time we'll take a high mileage usage pattern, typical of larger fleets, assuming 200,000km per year (125,000 miles per year)

Tesla – 83,000kg embodied + (10,000kg x 10 years) = 183,000kg CO2

Nikola – 20,780kg embodied + (40,784kg x 10 years) = 428,617kg CO2

RESULT - Nikola One/Two has 134% HIGHER life-cycle CO2 emissions than Tesla Semi at 40g CO2/kwh and 200,000km per year

SCENARIO 3 - Average km, average electricity CO2

At 400g CO/kWh and 100,000km /year, result is:

Tesla - 83,000kg embodied + (50,000kg x 10 years usage) = 583,000kg CO2

Nikola – 20,780kg embodied + (203,918kg x 10 years usage) = 2,059,964kg C02

RESULT - Nikola One/Two has 253% HIGHER life-cycle CO2 emissions than Tesla Semi at 400g CO2/kwh and 100,000km per year

SCENARIO 4 - Very low km, very low electricity CO2

We'll now assume that the truck does only about 50,000km (30,000 miles) per year, or about half that of average. It is rare that any business will have truck utilization this low.

Tesla - 83,000kg embodied + (2,500kg x 10 years usage) = 108,000kg CO2

Nikola – 20,780kg embodied + (10,195kg x 10 years usage) = 122,739kg C02

RESULT - Nikola One/Two has 14% HIGHER life-cycle CO2 emissions than Tesla Semi at 40g CO2/kwh and 50,000km per year

Obviously, with the new assumption from Nikola, the results are VERY different. Under EVERY scenario, the Tesla creates less lifetime CO2 than the Nikola truck. This climbs higher as the miles traveled increases, and the grid CO2 increases.

I'd now call lifetime CO2 emissions a big win for Tesla Semi

James Carter

Principal Consultant

Vision Mobility