Proposition: Fuel Cell Vehicles (FCV) cannot replace the UK fleet of passenger cars
The following calculations are to support the logic that FCV cannot replace the current Internal Combustion Engine powered passenger car population in the UK. This is the work of DR Colin Herron and not of my company. It is intended solely for discussion and information.
Data and assumptions to be applied
At the end of June 2016 there were 37.1 million vehicles licensed for use on the roads in Great Britain, of which 30.7 million were cars. Source: Vehicle Licensing Statistics: Quarter 2 2016 316.7 billion miles were driven on Great Britain’s roads in 2015. Source: Road Traffic Estimates: Great Britain 2015
Average Fuel Economy of all UK Cars: Combined mpg 37.83 www.fuel-economy.co.uk/stats.html
There are now 8,455 petrol stations in the UK (2013) Wikipedia
Average fuel capacity of an ICE car 10 gallons
Distance on full tank by an FCV is 300 miles (Toyota Mirai)
Hydrogen required to fill a Mirai is 5kg at 700 bar
To calculate average miles driven
Average miles per car is miles driven (316.7x 109) ÷ cars on the roads (30.7 x 106) = 10,316 miles Note: This is close to figures from the RAC of an average of 7,900 miles.
To calculate fuel required for annual gross UK mileage
If we use the combined mpg of 37.83 mpg to establish the amount of fuel used to cover 316.7 bn miles we get; (316.7x 109) ÷37.83 = 8.37 x109 or 8.37bn gallons
To calculate fuel required per fuel station per day
We take amount of fuel reqd (8.37×109) gallons ÷ number of fuel stations (8,455) and divide by 365. This gives a daily dispensing volume of 2,712 gallons per station per day.
What driving does 2,712 gallons allow?
Daily dispensing volume of 2,712 gallons ÷ average mpg (37.83) gives a total mileage capability of 102,594 miles per station per day.
How much hydrogen is required for the same mileage?
Using Toyota Mirai with a range of 300 miles and a fill requirement of 5kg.
102,594 ÷ 300 = 342 fillings @ 5kg which gives a hydrogen requirement of 1,710 kg per average filling station.
The next question is; how does the hydrogen get to the filling station? There are three possibilities:
1. Made on site by electrolysis
2. Delivered by tanker
Looking at electrolysis.
Delivering this much hydrogen by electrolysis is of course possible, however; the land required will be significant. The facility below has been built in Aberdeen to service buses. The production rate is 400kg per day which to service a demand for 1,710kg would require 4.2 facilities of this size. We know 55kWh to produce 1kg of H2 we also know we will require 2 gallons of water. So each car (5kg) requires 275kg and 10gallons of water to travel 300 miles. BEV requires 75 kWh to move the same distance which is 3.7:1 and the hydrogen requires pressurising and cooling .
With hydrogen refuelling stations costing circa £800,000, there are currently only plans to install a handful across the entire country. Currently London, Swindon and Rotherham are home to hydrogen refuelling stations and the UK Government has plans to bring the total up to 13 in the next year.
Manufacturers claim a hydrogen output from their containerised stations of between 25Kg and 500+ Kg per day. I would expect given experience of the Hydrogen Refuelling Stations (HRS) in Aberdeen that the higher figure is achieved through linking multiple containerised systems (the Aberdeen station produces about 20Kg per hour to fill buses but it has a very large footprint). Using a state-of-the-art 70 MPa refuelling dispenser, a few minutes refuel will provide most FCEVs with around 300 of range miles – as opposed to the half an hour rapid charge for a battery electric car offering around 100 miles of driving.
The smaller station that they are currently installing will be aimed at cars and will produce similar figures to those that companies such as ITM claim. A Mirai will take about 5Kg per tankful and give you approx. 300 mile range. (A bus 40kg and a 250 mile range). It is claimed that this equates to about 66 mpg given the trade off in price for a car. Aberdeen Council charge an equivalent price to Diesel but accept that they will have to subsidise the actual cost from EU funding.
The actual cost for hydrogen appears to be very much governed by the cost of compressing and dispensing it. This will depend upon the station chosen of course. ITM’s website shows a containerised station that will pressurise the H2 up to 350 bar. I note that both the Mirai and Hyundai have a 700 bar tank, although this does not need to be filled to this level as it will run quite happily at lower pressures, it will have a shorter range.
Using 2009 figures from NREL (USA)
A 100% efficient electrolyser requires 39 kWh of electricity to produce 1 kg of hydrogen. The devices today require as much as 48 kWh/kg. So, if electricity costs are 0.05 US$/kWh, (UK £0.15) the power cost for the electrolysis process alone is 2.40 US$/kg (£7.20) of hydrogen. Capital costs for an electrolysis facility can be a huge factor, and for smaller installations can actually become the predominant cost factor.
One advantage of electrolysis is that it is capable of producing high purity hydrogen (>99.999%), which is good for FCVs, whose fuel cells will, at least initially, be susceptible to contaminants and will require ultra-high hydrogen purity.
ITM’ own figures 2013
HGas 1MW (446kg/day) Generation Module:
A hydrogen generation module comprising sixteen HGas electrolyser stacks and associated balance of plant has been used in the analysis. In addition to capital cost and electricity consumption, the analysis includes an indicative annual maintenance cost and utilisation factor. The assumptions used are: Generation capacity: 446kg/24hrAmortisation period: 10 years Electricity price: 3.5p/kWhr Water price: 0.13p/litre System efficiency: 55kWhr/kg Annual Service: 5% of sale price Utilisation factor: 70%
This is a 400kg facility
Hydrogen cost is projected at £4.19/kg, a 32.7% reduction from last year’s £6.23/kg, within a 10 year capital amortisation period and £2.69/kg, a 22.9% reduction from last year’s £3.49/kg, after capital amortisation. The European cost targets for hydrogen generation are EUR9.90/kg (£7.92/kg*) in 2015 and EUR5.50/kg (£4.40/kg*) in
2025 (McKinsey: ‘A portfolio of power-trains for Europe: a fact-based analysis’). The refuelling equipment is quoted separately and is typically tailored to the user’s specific requirements. The costs associated with shipping the unit to site are not included as they are location specific.
Using the EU targets a 5kg a fill for 369 miles (Hyundai info) will be £40 at 2015 figures. Will their site will not be running at 70% utilisation. The diesel Hyundai equivalent (ix35) has a 58 ltr tank and a combined cycle of 5 ltrs per 100km. This gives a range of 1,160km or 725 miles. 58 ltrs at £1.16 per ltr is £67.
So cost per mile:
9.2p for diesel
Cost of conventional ix35 ranges from 17K to 27K, Mid-price of 22K. FCV ix35 has a cost of £53k
A 40ft trailer can deliver 300kg of hydrogen at 250bar. Therefore demand (1710) ÷ supply (300) = 5.7 tankers per day. To service all required filling stations would require 8,455 x 5.7 = 48,000 tankers per day. This defeats the object of CO2 saving if diesel trucks are used if the trucks are FCV it will create and additional requirement to fuel the trucks.
This would require a new national network to service filling stations on the primary road network
Hydrogen Energy Hub
The key to a low hydrogen price is a high utilisation of assets combined with a low electricity price achieved by grid balancing payments. One way of achieving high utilisation is by combining Power-to-Gas energy storage with refuelling. Two 1MW energy storage schemes that have recently been bid by the Company are appropriately located to add a dispenser in order to offer FCEV refuelling. This concept of a Hydrogen Energy Hub is being actively developed. This is however valid for small volumes of vehicles in a set location.
These figures are looking at producing 446kg in 24hrs at 70% utilisation. ITM figures suggest their 1MW equipment can service 92 cars a day, at 70% utilisation that is 65 cars.
Production (kg/24hrs)25 80 165 462Hydrogen Pressure (bar) 700 (350 bar option also available)Vehicle Refills (per 24hrs) 5 refills 16 refills 33 refills 92 refills
The estimated average annual mileage per car in England is 7,900 miles in 2015. Company cars have an annual mileage more than double that of private cars (18,300 compared to 7,500).The estimated average annual mileage was higher for diesel cars than petrol cars, at 10,700 miles and 6,500 miles respectively in 2015.
Source: National Travel Survey: England 2015 and Table NTS0903
The total road length in Great Britain in 2015 was estimated to be 245.9 thousand miles. Compared to previous years, total road length in Great Britain in 2015 was 100 miles greater than in 2014, an increase of less than 0.1 per cent and 5.8 thousand miles greater than in 1995, an increase of 2.4 per cent.
The length of motorways in Great Britain in 2015 was estimated to be 2.3 thousand miles. “A” roads in Great Britain accounted for 29.1 thousand miles of road in 2015. These major roads make up 12.7 per cent of total road length.
The majority of road lengths in Great Britain is made up of minor roads, with these roads accounting for 214.5 thousand miles in 2015 (18.8 thousand miles of “B” roads and 195.7 thousand miles of “C” and “U” roads). These minor roads make up 87.3 per cent of the total road length