Emission Impossible: What’s the ‘greenest’ fuel for urban transport?

Mark hurst reports on the different fuels available for cleaner transport solutions and asks how easy is it to be a truly green transport/fleet manager?

THE CONTINUING debate on climate change and how to tackle it has grown recently. Startling new evidence has included the Ayles ice island that broke away from the Canadian arctic coast and has been found floating only recently. At around 10 miles long and 3 miles wide, it is being closely monitored. And for proof that there is a God, the floating Ayles island is now considered to be a threat to the oil and gas installations off Alaska – the irony of which, if it doesn’t make you cry should make you laugh.

But as the debate about climate change expands, other environmental concerns about local air quality in the UK are starting to enter a new phase with the introduction of London’s Low Emission Zone (LEZ) in 2008.

Balancing local and global environmental concerns is a complicated task, which transport and fleet managers must attempt to address. Road transport powered by the internal combustion engine emits a lot more than just carbon dioxide. A range of compounds are emitted, dependent on the fuel used. It’s balancing the environmental impact of this emission cocktail, which is the greatest challenge.
 
Diesel vs. Petrol
Diesel vehicle ownership has increased over the past few years, prompted by lower fuel and taxation costs. The good news is that diesel vehicles produce around 20 per cent less CO2 emissions than petrol-powered vehicles. With respect to tailpipe emissions that are important to the global environment, diesel powered vehicles are fairly ‘green’.

The drawback with diesel emissions is with contaminants whose importance lies in local air quality, especially in urban areas. Diesel emissions fare much worse than petrol emissions, with a 20-fold increase in levels of particulates which can contribute to respiratory and heart problems. Currently, this is calculated as producing around a 1000 premature deaths per year in the UK.

So how do you assess the balance between less CO2 but with greater particulates? Scientists at the University of British Columbia have attempted to calculate the cost-benefit of diesels, although the interpretation of this calculation proves more difficult. They have estimated the increased use of diesel vehicles in the UK will reduce total CO2 emissions between 2001 and 2020 by up to 7 mega tonnes but at a cost of raised particulate emissions by 12 kilo tonnes, causing 90 extra deaths in the UK. Seven mega tonnes CO2 reduction against 90 premature deaths?

While you consider how many tonnes of CO2 reduction a premature death is worth, the positive news with particulates is that they are reasonably easily removed by particle traps and other forms of filtration. So local air quality can be improved along with lower CO2 emissions. The introduction of London’s Low Emission Zone will assist this with legislation aimed at improving air quality in the London area. The first goal is to reduce particulate emissions in large commercial vehicles utilising the Euro standards, and targeting the oldest and most polluting diesel vehicles. The scheme allows for vehicles to be upgraded using retrofit emissions technology, which is the most cost effective in both financial and environmental terms. The LEZ scheme will allow Londoners to breathe more easily and be able to rest more easily knowing the London Barrier will have slightly less likelihood of being breached. Although, until the LEZ is expanded to all commercial vehicles and private vehicles, the lower CO2 benefit of diesels will not be truly felt.

Petrol vs. Biopetrol (Bioethanol)
For petrol-powered vehicles, bioethanol is currently seen as a potential replacement. Sadly, as pointed out in my previous GreenFleet article, the first evidence of the biofuel conflict with food production is coming to fruition in Mexico. The US demand for maize to produce bioethanol has doubled the price of the Mexican’s staple corn bread, or tortilla, causing the 75,000 protesters in Mexico City to descend into an angry mob in February.

As well as almost causing riots, bioethanol produces marginal savings in CO2. But what about the impact of bioethanol on local air quality? The positives for bioethanol include much lower emissions of carcinogens like benzene, which is obviously good news. The negatives include much greater emissions of aldehydes, with some studies showing up to 20 times the level of aldehydes emitted when using bioethanol when compared to petrol. Aldehydes are a constituent of smog and react with sunlight to form ozone, another constituent of smog. Studies have only been conducted in the USA to try and assess the impact of widespread usage of bioethanol.

A paper published in Environmental Science & Technology suggests that an 85 per cent bioethanol blend (E85) used across the USA would cause 185 more pollution-related deaths per year when compared to a petrol fleet. The true carbon saving of bioethanol then needs to be assessed alongside this.

Diesel vs. Biodiesel
The use of biodiesel versus diesel in urban zones produces some interesting comparisons. Biodiesel produces lower tailpipe emissions of particulates and large reductions in hydrocarbons, but about a 10 per cent increase in nitrogen oxide (NOx) emissions, a smog forming pollutant (and potent greenhouse gas). Overall, biodiesel produces an increase of smog forming pollutants. The good news for biodiesel is NOx emissions can be reduced through the use of engine modifications and exhaust after-treatment devices, especially effective, as biodiesel is low in sulphur.  NOx emissions will be included in the London LEZ from 2010 and this will help maintain cleaner air as biodiesel attempts to reduce CO2 emissions.

Other fuels
Electric vehicles powered from batteries provide the lowest tailpipe emissions at zero. For urban areas, these are clearly the best vehicles to use and are becoming more economical, with a zero congestion charge and vehicle excise duty. The technology is continually improving, providing vehicles with a greater range and ease of use. Charging stations and battery exchanges for urban areas should now be a priority. Although electric vehicles produce zero tailpipe emissions, the power used for charging these vehicles must come from a low carbon non-polluting renewable source, such as wind. The concern, from some quarters, is producing enough power from wind. Advancing technology is key, along with the political will. Scientists from Stanford University have recently produced a global wind-energy resource map. They have estimated the global potential for wind-generated energy at 72 terawatts. To put this in context, the current overall global power demand is around 2 terawatts. Not enough wind they say?

Emission impossible: Being a ‘Green’ Transport/Fleet Manager
The complicated nature of the internal combustion engine means all manner of compounds are emitted from the tailpipe, dependent on the fuel type used. Overall, technology applied in removing most of these, coupled with legislation to drive the implementation of cleaner tailpipe emissions, should improve local air quality. For combating climate change we all need to look at the much larger picture and assess carbon emissions using a holistic approach.

Since my last article outlining some of the drawbacks of biofuels in combating climate change, specifically biodiesel, there have been some interesting debates taking place in the general and science media. Biofuel bashing seems to have come into fashion recently with The Sunday Times getting involved with the headline ‘Top scientist says biofuels are scam’ (June 10). The top scientist, Roland Clift, is a senior science advisor to the UK government’s environment department and said: “Biodiesel is a complete scam because in the tropics the growing demand is causing forests to be burnt to make way for palm oil and similar crops”.

Although cracks are starting to appear in the biofuels strategy, the UK government are still keen on expanding the role of biofuels along with the EU, whose leaders agreed new targets in March to increase biofuels usage from 5 per cent to 10 per cent by 2020. Professor Clift also stated in The Sunday Times article: “We calculate that the land will need to grow biodiesel crops for 70-300 years to compensate for the CO2 emitted in forest destruction.” The biofuels strategy seems plain idiotic unless you realise that the current biofuel policies used by the UK, EU and US governments are more about providing energy-security rather than eco-security.

Biofuels are coming under more and more attack and from a climate change point of view, the evidence for their expanded use is looking very shaky. The only way forward, in my view, is one put forward by the environmentalist, George Monbiot – a five-year moratorium on biofuel production, similar to that for GM crops, to really assess their true environmental benefits or weaknesses. If this step back was taken and government took the time to produce a joined-up concerted view, other alternatives to biofuels may present themselves.

It was recently pointed out by the Global Canopy Programme based in the UK that an easier way of reducing climate change was to pay countries to not destroy rainforest. The potential to prevent CO2 emissions is huge, as deforestation accounts for 18 per cent of all emissions. The problem though is that currently conserving rainforest is excluded from today’s schemes for trading carbon credits.

Anti-deforestation schemes should be introduced in December, when the UN Framework Convention on Climate Change convenes in Bali. The current Kyoto protocol only allows credits for newly planted forests, so farmers receive more money for cutting down forest and replanting than if the original forest was left alone.

To combat climate change we will require joined up strategies, policies and guidance from the government. Currently this is not happening, with the tough decisions being put off, scam solutions being championed and real solutions not having the framework to get off the ground. This framework could be provided by the inclusion of transport in the EU Emission Trading Scheme (ETS), which could offer a cost-effective way for the sector to reduce its impact on climate change. The EU ETS directive is considering surface transport as one of the sectors that could be included in any expansion of the scheme. So in the future, instead of paying for rainforest to be ripped up, burnt and destroyed, you could be paying for them to be left alone. Which option will future generations thank us for?