The use of cleaner and lower carbon-density fuels is an important way of improving local air quality and tackling climate change. Nearly all transport fuel (95%) is supplied by petroleum, contributing 26% of global carbon dioxide emissions.
Cleaning existing fuels
Lead has largely been phased out of fuel in Asia and, following the Dakar Declaration of 2001, in Africa too. Benzene is another pollutant in petrol, a toxic carcinogen that can be released during movement, storage and combustion. The inefficient burning of fuel also releases carbon monoxide, particulate matter, nitrogen oxides, and ozone. All these pollutants have a serious health impact, which can be addressed by simultaneously improving vehicle engine technology and providing cleaner fuels.
The 'fuel challenge' part of the equation in the developing world is to progress the introduction of ultra-low sulphur diesel (ULSD) and petrol. Used with appropriate technology to reduce fuel consumption, ULSD can deliver carbon dioxide reductions in the order of 20 to 45%. Local pollutants such as particulate matter and hydrocarbons can also be reduced by up to 97% on the equivalent emissions of standard diesel. However, experts have found levels of NO2 to be in the order of four times higher than for petrol driven equivalent cars.
One of the most commonly cited barriers to the introduction of ULSD is its cost. Refinery systems need to be modified requiring high levels of up front investment. However, research conducted by the International Council on Clean Transportation found that costs ranged from between 0.25 to 1.20 cents a litre. The introduction of regulatory and price mechanisms can provide the necessary incentives for a switch. In Germany a tax of 0.015 euros or 1.2 cents on high sulfur fuel led to a reduction in average levels of between 3 and 5 ppmv.
One fuel-shift taking place is a move towards using biofuels for transport energy, especially in the USA and Brazil. Biofuels can reduce dependency on imported fuel. Biofuels also have a low carbon footprint and are as energy-efficient as petrol and diesel.
Brazil has the largest biofuel production programme in the world, with an enviable 10:2 energy output: input ratio. Brazil processes bioethanol from sugar cane grown on 1% of the country's arable land. Biodiesel derived from soyabeans is also produced. Roughly a third of the world's biofuel production is based in Brazil, catering for nearly half the country's demand for transport fuel.
It is endowed with a number of competitive advantages for the production of biofuels. Brazil's climate and soils are diverse enough to facilitate large-scale production processes. The country has a large amount of disposable land, including forest, which is sufficiently low in price to allow investment in biofuel production. Lower labour costs in Brazil also help to keep prices competitive.
The US set a target in 2006 for 75% of its energy to be derived from non-petroleum based sources by 2025. A European Union regulation requires 5.2% of transport fuel to be supplied by biomass by 2010. But experts question whether the US and Europe can match the competitive advantages enjoyed by Brazil and, even if they could whether it would be desirable to do so. At the recent G8 summit in Japan Robert Zoellick, Head of the World Bank, criticized the role of biofuels as a significant contributor (75%) to the rise in world food prices. The main factor, according to Zoellick, is the diversion of land away from food to fuel crops, particularly in the case of US corn production.
Some research has also found that, if all energy demand is taken account of in the production of biofuel, the well-to-wheel emissions rise significantly. In the developing world, challenges include the need for sophisticated systems to collect fuel crops from thousands of small farmers. This would require immense efforts of co-ordination and control to ensure fuel becomes available and quality standards are maintained.
Hydrogen fuel is a promising energy source that emits only water at the vehicle tailpipe. It can be derived locally, reducing dependency on imported fossil fuel and can also be heavily compressed, allowing enough of it to be stored on a vehicle for longer-range use between re-fuels.
It is hoped that hydrogen could be developed in its own right as a transport fuel. However, this would not be easy to achieve in a short time frame. Issues remain over the cost of extraction, battery performance, the use of fossil fuel-based energy to manufacture hydrogen, not to mention safety issues regarding the low-pressure storage of hydrogen fuel.
In an effort to fuel R&D and bring down costs, some cities have introduced hydrogen fuel to small segments of their bus fleets (link). However, this has generally shifted the source of carbon dioxide emissions from tailpipe to the site of manufacture. Compressing hydrogen fuel for storage is highly energy demanding.
Given the energy intensive nature of hydrogen fuel production one of the biggest hurdles will be the difficulty of finding enough renewable energy with which to manufacture it. In the very best cases, renewable energy in Europe caters for more than 15% of the present total energy demand.
Iceland is conducting a pilot study, using hydrogen fuel for transport. However, Iceland has comparative advantages in the renewable energy stakes; the country is endowed with large quantities of geothermal energy. More information on future developments can be obtained through the EU's Hydrogen and Fuel Cell Technology Programme which is presently structuring socio-economic and technical research into hydrogen fuel.