Air quality: A follow up report - Environmental Audit Committee Contents

Written evidence submitted by Country Land and Business Association (CLA)


The Country Land and Business Association (CLA) represents some 35,000 members who between them own and manage half the rural land in England and Wales. We have long taken a deep interest in energy policy, as our members manage a large proportion of the resources that may be brought to address climate change.

In the course of this work we have investigated the development and use of biogas from Anaerobic Digestion, have undertaken international study trips and supported the work of Task 37 (energy from biogas and landfill gas) of the International Energy Agency.

Biogas when upgraded to bio-methane is an almost perfect renewable transport fuel.

We are disappointed and confused that UK policy has so far missed the huge potential for biogas to address both arms of air quality: reducing the emissions of GHG in transport, while at the same time delivering improved air quality through significant reductions in particulants and noxious tailpipe emissions.


—  The role of "dirty" diesel transport in poor air quality (particularly in urban areas).

—  The poor performance of electrification in road transport, particularly for buses and HGVs, especially taking into account current grid average GHG and emissions from conventional electricity generation.

—  The EU comparisons between hybrid and CNG.

—  The "stepping stone" and security of supply back up provided by full switchability between natural gas and bio-methane.

—  The flexibility of dual fuel vehicles and the low costs of switching.

—  The clear and obvious example of significant benefits shown in Sweden.

—  The failure of UK policy to address the role of biomethane in transport.

The role of "dirty" diesel transport in poor air quality (particularly in urban areas)

1.  The CLA does not claim expert knowledge of the relative air quality impacts of different transport fuels, but notes that where air quality has been found a problem elsewhere in the world, changes to transport policy has delivered benefits. For example many cities across the world have limited entry by vehicles to reduce pollution. In India, some authorities have required "tuk tuk" taxis to switch to running on gas to reduce emissions.

2.  It is clear that even modern "cleaner" diesels produce significant disbenefits to air quality, and rather than restrict the use of such vehicles, with significant effects on the economy and society, alternative fuels may offer a better solution.

The poor performance of electrification in road transport, particularly for buses and HGVs, especially taking into account current grid average GHG and emissions from conventional electricity generation

3.  We have noted that Transport for London has invested significant sums in new hybrid electric buses. These are recharged with grid average electricity, at 0.57098kg/kW (taken from 2010 Guidelines to Defra / DECC's GHG Conversion Factors for Company Reporting.[1]

4.  However, these buses are extremely expensive: Transport for London states "Hybrid buses currently cost approximately £110,000 more than a conventional diesel bus. For example, a hybrid double deck bus for London would cost £300,000 compared with £190,000 for the diesel equivalent. Initial indications are that maintenance costs are about the same as a conventional diesel bus, although replacement of batteries after about five years will require further capital investment".

5.  Transport for London claims "Compared with diesel buses, hybrid buses deliver environmental benefits, including:

—  Minimum 30% reduction in fuel use.

—  Minimum 30% reduction in carbon dioxide.

—  3 decibel [dB(A)] reduction in perceived sound levels.

—  Reduced oxides of nitrogen and carbon monoxide".

6.  In contrast, recent research[2] for the Baltic Biogas Bus partnership undertakne by the VTT technical research centre of Finland states that:

—  Currently new (EEV certified) methane buses clearly outperform new (EEV certified) diesel vehicles for NOx as well as PM.

—  methane vehicles provide true EEV performance over time.

—  All methane fuelled vehicles deliver very low PM emissions.

—  stoichiometric vehicles deliver lower NOx and lower fuel consumption.

—  Clear benefit for methane also for unregulated emissions (PM numbers,aldehydes, PAH, direct NO2 emission etc).

—  Main drawback of spark-ignited methane compared to diesel is higher energy consumption.

The lower energy yield of methane in engines means that CO2 emissions are roughly equivalent between diesel and methane power, but this has been fixed in Sweden by switching from natural gas to bio-methane.


7.  ComPro, the EU common procurement office undertook a comparative study of bus technologies, with a side by side comparison of the costs and benefits of the alternatives, based on CNG buses[3]. This is précised below:

Comparative cost/effectiveness analysis between CNG bus and DEhybrid technology

—  Experience in Europe CNG technology is much more experienced, while DE-hybrid is only partially experienced.

—  Extra infrastructure CNG needs an extra natural gas filling station to be built; for already existing filling station, the possibility of saturating its capacity represents an advantage.

—  Range DE-hybrid can assure an higher range, while CNG provides a reduced range depending on the availability of a natural gas filling station.

—  Pollution DE-hybrid technology strongly reduces Pm, NOx and CO2 emissions, while CNG technology is responsible for higher CO2 and no PM emissions.

—  Fuel consumption is concerned: DE-hybrid strongly reduces fuel consumption.

—  Fuel cost diesel cost is rapidly increasing (in Italy one litre diesel costs so much as one litre gasoline, that is 1,5 euro), while natural gas costs almost half so much as diesel.

—  Vehicle cost is concerned: DE-hybrid buses cost about 120.000 euros each more than CNG ones.

—  Noise is concerned: DE-hybrid buses are less noisy than CNG ones.

—  Energy source dependence is concerned: there is a reduced dependence on energy import by DE-hybrid technology, while CNG technology depends on natural gas import.

8.  The key issue for urban transport is whether hybrid is the way forward, or to adopt CNG as a stepping stone to a renewable future based on bio-methane.

9.  The capital costs of replacing bus fleets with hybrids (at least an additional £100,000 per vehicle) together with the slow progress (waiting for existing buses to be retired) may be considered to be less advantageous than an early conversion of existing buses to dual fuel.

The "stepping stone" and security of supply back up provided by full switchability between natural gas and bio-methane

10.  Bio-methane (produced from Anaerobic Digestion) is identical to natural gas, being almost completely methane. Current supplies of natural gas are available wherever fuel supply is required through the national gas grid (save in the rural areas).

11.  Vehicles converted to run on natural gas require no further work to switch to use of bio-methane, and should renewable supplies run short natural gas is available.

12.  Pending decisions on the environmental performance and regulatory framework, supplies of shale gas may well contribute to security of supply.

13.  The development of gas filling stations and the conversion of vehicles is relatively cost effective.

The flexibility of dual fuel vehicles and the low costs of switching

14.  Hardstaff is the leading supplier of "dual fuel" vehicles[4] and can readily supply conversion for buses fitted with electronic fuel injection systems, at cost effective prices. They currently supply a range of heavy good vehicles (Mercedes Benz and Volvo) and have over 80 million kilometres of dual fuel operation.

15.  Many cities around the world have switched to gas for bus transport - the UK is almost unique in seeking more expensive hybrid technology.

16.  The ComPro report suggests that the additional costs of GNG buses is only 30,000 Euro per vehicle.

17.  Duel fuel offers opportunities for more extensive air quality benefits as it is also suitable for long distance transport fleets of HGV and smaller lorries.

The clear and obvious example of significant benefits shown in Sweden

18.  In 2010, with sponsorship from the FCO, CLA joined with Task 37 to take two DfT officials on a fact finding visit to Sweden to explore the use of gas as a vehicle fuel.

19.  It was clear to all that in Malmo the use of biogas to fuel buses has lead not only to significant air quality benefits but also to meeting renewable energy targets and reducing noise pollution.

20.  Sweden has a well regulated and highly developed bio-methane transport policy, which currently delivers significant quantities of sustainable clean fuel.

21.  During 2006, almost 24 million normal cubic metres of biogas were used as vehicle fuel in Sweden, which is equivalent to 26 million litres of petrol. 2006 was the first year in Sweden when more biogas was sold as vehicle fuel than natural gas (biogas comprised 54% of the total volume).

22.  Swedish regulations require low sulphur and particulate content in the fuel, leading to very low tailpipe emissions.

The failure of UK policy to address the role of biomethane in transport

23.  Hybrid technologies cannot themselves deal with the air quality agenda.

24.  However, concentration on hybrids and liquid biofuels has led to the under-development of biomethane as transport fuel.

25.  The use of biomethane is not adequately supported in the UK, compared to other countries like Sweden.


26.  DfT should consider the necessary policy actions required to ensure a large scale switch of the UK bus fleet to:

—  Dual fuel (gas and diesel).

—  CNG and LNG.

—  Bio-methane.

27.  Once buses and HGV are capable of running on gas, it is a short step to switch over to bio-methane as soon as supplies are available.

28.  Operators of dual fuel vehicles have evidence to show cost savings may be achieved as well as improved air quality. DfT should take time to talk to Hardstaff (a leading British Company) to learn what is needed to widen the use of dual fuel buses.

29.  CNG and LNG buses are widely available across the world. UK lags behind the adoption of this beneficial fuel use which is rapidly growing in other countries.

30.  Bio-methane is a direct replacement for natural gas, and enables climate change benefits to be added to the air quality benefits of running buses on gas.

31.  The supply of bio-methane is limited at present, but should grow as more AD plants install upgrading and connect to the gas grid with support from the recently announced Renewable Heat Incentive. In order to drive the uptake of bio-methane in the transport sector, the Renewable Transport Fuel obligation should be amended so that the number of certificates awarded per litre reflect the GHG savings achieved (on a whole life cycle basis) of the fuel


32.  There is an obvious and relatively inexpensive route to better air quality, which does not depend on re-equipping bus fleets with expensive and short life battery powered hybrid vehicles (batteries have a relatively short life compared to internal combustion engines).

33.  Equally, wider air quality benefits would be delivered by better incentives to take up CNG and bio-methane in transport fleets.

34.  DfT should require and work with bus operators to ensure they adopt gas, and rapidly move them up the scale towards a bio-methane powered sustainable bus transport system for urban areas - as is demonstrated in Malmo, Sweden.

24 May 2011

1   Annex 3 at  Back

2  Back

3  Back

4  Back

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© Parliamentary copyright 2011
Prepared 14 November 2011