HC Deb 19 February 1990 vol 167 cc537-8W
Mr. Barry Field

To ask the Secretary of State for Trade and Industry if he will set out the research and findings that have been given by Warren Springs laboratories on carbon dioxide emissions from vehicles with and without catalytic converters.

Mr. Douglas Hogg

WSL has made no direct comparisons between catalyst and non-catalyst versions of popular makes and models of cars. Catalyst-equipped versions of these vehicles have not been available.

Our experience of catalyst cars is confined to specialist imports and manufacturers' prototypes, with relatively new catalysts.

We will measure emissions from production catalyst cars as they become available in the vehicle parc.

Our experience with relatively new catalysts shows a conversion efficiency of 80–90 per cent. for CO, hydrocarbons and NOx WSL has done no work as yet on degradation of catalyst performance with age, in use.

In non-catalyst cars, the CO and HC emissions would ultimately be oxidized to CO2 in the atmosphere over periods of several months. Catalysts effect this oxidation at the tailpipe immediately.

Number of defendants Security(ies) Involved Date(s) of Offences or alleged Offences Outcome
2 Joseph Stocks and Sons (Holdings) Ltd. 11 December 1980 and a day between 15 April 1980 and 11 December 1980 Both convicted
1 Harris and Sheldon Group plc Day between 4 June 1981 and 18 June 1981 Convicted
2 Blockley plc 9 August 1982 Acquitted
1 Martin the Newsagent plc 6 March 1984 and 9 March 1984 Convicted
1 Thomson T-Line plc 5 December 1985 Acquitted
1 Reardon-Smith Line plc 28 May 85 Convicted
1 AE plc and Cadbury Schweppes plc 3 November 1986 and 14 October 1986 Convicted
1 The British and Commonwealth Shipping Co. plc and Steel Brothers Holdings plc 14 October 1986 and 14 November 1986 Convicted
1 Wordplex plc 30 April 1987 Acquitted on Appeal

The difference in CO2 emissions between models with or without catalysts therefore depends almost entirely on the respective fuel consumptions. At present, catalyst vehicles have to operate at relatively rich air-fuel ratios, leading to a fuel consumption penalty of the order of 10 per cent.