HONDA is becoming a fuel for your environmental love - it has just unveiled next-generation power plants, the key to its global initiative to cut carbon dioxide emissions.

The Japanese giant now has a diesel engine that reduces exhaust gas emissions to a level equal to a petrol engine, but, perhaps more importantly, has just held a demonstration drive of the next-generation FCX Concept fuel cell vehicle.

Limited marketing of a totally new fuel cell vehicle based on this FCX concept model is to begin in 2008 in both Japan and the United States.

Aside of environmental gains, the FCX is a low-floor, low-riding saloon, with a short-nose body that will help improve driving performance, too.

It's equipped under the bonnet with a high-efficiency fuel cell stack, arranged in an innovative centre-tunnel layout that has allowed designers to create the elegant saloon shape that would have been difficult to achieve in a conventional fuel cell vehicle.

This new fuel cell stack is 20 per cent smaller and 30 per cent lighter than the FCX fuel cell stack that was first paraded last year in Tokyo, yet its power output is greater.

Overall, the power plant is about 180kg lighter than that of the last FCX, and about 40 per cent smaller in volume.

Honda says that with previous fuel cell stacks, the hydrogen and the water formed in electricity generation flowed horizontally - the new FCX features vertical-flow design which allows gravity to help discharge the water that is produced, resulting in a major improvement in drainage, vital to high-efficiency fuel stack performance.

As an auxiliary power source, the FCX Concept carries a compact, high-efficiency lithium ion battery, which contributes to the increased power output.

In terms of engine efficiency, the FCX has an energy efficiency of around 60 per cent - approximately three times that of a petrol-engined car, and twice that of a hybrid vehicle.

On the diesel front, it is Honda's new catalytic converter that helps cut exhaust emissions on the firm's its 2.2 i-CTDi diesel engine, which has already earned wide praise for quiet, clean operation and dynamic performance since it appeared in 2003 on the European Accord model. Basically, the new catalytic converter detoxifies nitrogen oxide emissions in its diesel engine by turning them into nitrogen.

Lower emissions are also a major feature of Honda's advanced VTEC (Variable Valve Timing and Lift Electronic Control System) technology, with the development of an advanced new VTEC engine.

This power unit achieves high performance, outstanding fuel economy, and those vital lower emissions.

Honda plans to release a production vehicle equipped with the new engine within three years.

Finally, bio-fuel hasn't been forgotten - Honda has also announced that it has developed a new flexible fuel vehicle (FFV) system that enables petrol engines to operate on either 100 per cent ethanol, or a wide range of ethanol-petrol fuel mixtures.

The FFV system will be launched in Brazil this year, a major producer of bio-ethanol fuel from its plant sources, such as sugar cane. Good science students will know that, because plants absorb carbon dioxide via photosynthesis, the amount of this gas released into the atmosphere from burning bio-ethanol fuel does not increase atmospheric carbon dioxide levels.

This makes bio-ethanol fuel an effective means to combat global warming, as well as a realistic alternative to petrol use.