Sustainable Fuel - the way forward to help protect the environment

ADVANTAGES OF AFS SUSTAINABLE FUEL

• If renewable energy is used to drive the CO2 extraction process and the hydrogen production by electrolysis of water, the fuel cycle would be carbon neutral.
• The UK and any country could have its own indigenous supplies, thereby removing all the geo-political problems of hydrocarbon fuel supply.
• The method does not require a fuel producer to be an oil company to manufacture fuels or for the consumers to be dependent on other countries.
• AFS would allow sustainable growth for the aviation industry.
• The cost of CO2 in the air is not going to get any more expensive and AFS manufacturing inflation costs should match that of the economy in general. Without any geo-political pressures on the price, AFS fuel price should remain fixed in real terms.
• Once developed, it would be possible to expand AFS production to meet the needs of all transport sectors and in all countries.
• AFS offers a way to store renewable electricity.
• AFS offers a way to regulate the CO2 content of the Earth’s atmosphere by pumping surplus oil back down the empty oil wells and at the same time creating a massive energy reservoir.

Alternative transport fuels

There are three basic routes that might be adopted to meet the needs for transportation fuel supply in a world where fossil fuels are becoming increasingly expensive and in short supply, these are:

1. Hydrogen
2. Biofuels
3. Synthetic Hydrocarbons

Hydrogen

Hydrogen is well recognised as a very useful mechanism for storing energy and may well play a vital role in helping to buffer surplus renewable energy supplies in the future. Hydrogen burns without producing carbon dioxide or particulates and so is an ideal transport fuel. Although not insurmountable hydrogen is bulky to store and requires particular attention to design if it to be properly contained. It is often promoted as zero-carbon, which it is at the tail pipe, however, since electricity is required for the electrolysis,  it could be some time before there is sufficient renewable electricity to replace the use of fossil derived electricity and for hydrogen fuels to truly earn their zero carbo title. 

To make hydrogen  available as a fuel requires modifications to be made to vehicles, typically as an injection system or fuel cell. It also requires the role out of hydrogen filling stations and potentially grid reinforcement to cope with extra demand for electricity. This of course creates a significant cost barrier and all of these factors make it difficult to conceive of a hydrogen powered commercial airliner.

AFS believes that a better use for hydrogen is to convert it into a standard liquid transport fuel that can be accessed by the public at large without the significant cost overheads.

Biofuels

BioEthanol and BioDiesel are the most common biofuels available today. Treated carefully these are fuels that can be blended into the existing fuel infrastructure and used directly in existing vehicles.Being based on biomass it can be argued that these fuels reduce the amount of greenhouse gas emissions from tailpipes on the basis that carbon dioxide emissions are offset by carbon dioxide absorbed by the biomass. Serious questions have been raised about the sustainability of biofuels, the impact they might have on food availabilty and the difficult to quantify direct and indirect effects of land use change. 

AFS believes that biofuels have an important role to play in the transport sector although their uptake will be limited.

Synthetic hydrocarbons

Traditionally the third route is the synthesis of fuels by the gasification of carbon containing materials, such as trees and waste materials, to form a mixture of carbon monoxide and hydrogen, (called Syn Gas) followed by the reaction of the gas mixture (via the Fischer-Tropsch (FT) process) to produce a hydrocarbon mixture.

Synthetic fuels made via FT have the advantage of being straight replacements for the current transport fuels and would not therefore involve a change in the market infrastructure. To date, the limited commercial use of FT has used coal or natural gas as the carbon feedstock, but for a sustainable supply of fuel the carbon feedstock will have to be from renewable resources. The carbon feedstock might be any biomass material, but it is dubious if enough biomass will be available throughout the world to meet the world's fuel needs.

The Syn Gas that may be derived from many carbon sources requires the H/C ratio of the mixture to be adjusted to the optimum. One way to do this is via the water-gas shift reaction:

CO + H20 CO2 + H2

A consequence of this reversible reaction is the recognition that CO2 alone could be the carbon feedstock, which when mixed with hydrogen could be used in an FT reaction to make fuels. The obvious source of the carbon dioxide is the atmosphere. The key step that is required is an economic route to extracting carbon dioxide from the air. The hydrogen component could be produced by electrolysis of water. Such a fuel production route would bring the following advantages:

1. With renewable energy used to extract the CO2 and electrolyse water, the fuel cycle is carbon neutral.
2. The UK or other country could have its own indigenous supplies, free from geo-politics.
3. It avoids the need to change the market infrastructure for vehicles and solves the aviation fuel problem. (aircraft need hydrocarbon fuels)
4. It does not compete for arable land as do biomass based fuels.
5. It will encourage the large scale implementation of renewable energy, especially solar and wind.
6. The route is a solution to sustainable transport fuels.