It is now a substantiated fact that the steadily increasing atmospheric CO2 level from man's fossil fuel based energy production is causing global warming, and that this will cause catastrophic damage to the 'biosphere' within a century unless addressed by a solution that replaces our energy sources by non-fossil fuel alternatives.

Analysts have shown that we have less than fifty years in which to act. We need a reduction in our fossil fuel burning that will be worldwide, viable in the short term, and deep in its impact. For this to occur in a market driven world economy, it needs to be a system that is economic, and technically viable right now.

The only way this will happen is if the worldwide energy companies have a positive choice for a new way forward, retaining their businesses and infrastructure. It is indeed only the energy companies that have the financial resources and necessary focus to address the problem. I believe the concept in this short paper does offer a solution, which has the required incentive.

Hydrocarbons are excellent energy carriers. Liquid hydrogen is impractical for many vehicles because it cannot be kept from evaporating. The transport infrastructure of the planet has been built around hydrocarbon energy carriers. We now appreciate the real cost in terms of global warming, of pumping all that carbon out of the ground and releasing its combustion product into the atmosphere. Approximately 60% of all the carbon extracted has remained in the atmosphere to date, raising the CO2 content from 280ppm by volume to 380ppm by volume. The change to the weather and climate is already becoming apparent.

Oil extraction is responsible for over 50% of the atmospheric CO2 build up. The overwhelming need for renewable fuel for transport has not been addressed. Massive production of bio-fuels would use too much of the Earths arable land.

This document seeks an answer to these problems by proposing that in the future, our hydrocarbon energy carrier medium will be synthesised from carbon dioxide extracted from the atmosphere, rather than from carbon pumped from the ground, and hence the whole petrochemical industry could become carbon neutral.

Non-fossil fuel sources of electric power such as concentrated solar power (CSP) or photovoltaic (PV), together with raw materials of air and water, will be used to extract the CO2 from the air, and recombine it with hydrogen (produced by the electrolysis of water) to make recycled hydrocarbons.

For this to be feasible, four main requirements must be met: 1) The most economic solar power generation feasable. 2). An energy efficient process for atmospheric CO2 extraction. 3). An energy efficient method of water electrolysis for the production of hydrogen. 4). An energy efficient process for catalytic hydrogenation of the CO2, to generate the final plant output of high-grade kerosene and other hydrocarbons.

Large-scale solar energy capture is possible in desert regions such as the African Sahara or the Western Australian desert. In these regions land is cheap, and the number of clear 'blue sky' days is high, leading to the viability of electricity generation using CSP (concentrated solar power) technology. Focussed solar parabolic collectors with 'Stirling' engines running generators, or solar trough collectors using more conventional turbines are already manufactured, and are being deployed in the Mojave desert near Las Vegas USA on a medium scale trial. These have demonstrable solar conversion efficiencies of up to 40%, which lead to a generating cost of about $0.10 to $0.12 per KWhr. A pilot with a ten-kilometre-wide square of this form of PV could produce an average of 5,000 Megawatts using existing technology at an estimated capital cost of £5Bn-£10Bn. It is important to appreciate that the best places for capturing solar energy are remote and not necessarily suitable for transmitting the electrical power generated to urban areas where it can be used directly.

Extraction of the CO2 from the air can be done chemically or physically. There are already existing chemical methods which recycle the active chemicals. These encompass alkali metal hydroxides, calcium hydroxide, sodium or potassium carbonate, or organic absorbers. Molecular-sieve materials, using temperature or pressure cycling, offer another method of extraction, which is currently used by British Oxygen to remove CO2 in their processing plants. Carbon dioxide can also be extracted from air physically using pressurisation and expansion. The ultimate efficiency of the process requires the dedicated skills of chemical and mechanical engineers, but the method chosen must be clearly energetically viable, and result in a plant size which small, but meets the throughput requirement. Alkali solutions such as sodium hydroxide appear to meet these demands. Generation of hydrogen by electrolysis has improved in efficiency, and is already at a commercial phase.

Hydrogenation of CO2 directly to methane, methanol, and even octane exists in the research and patent archives. Many researchers have demonstrated this reaction using various combinations of pressure, temperature and catalyst. Pressures of 300 bar, and temperatures of 300degC are typical. Because a lot of the energy required by this 'uphill' reaction is supplied by the mechanical work required to pressurise the reactants, the chemical reaction itself can even be slightly exothermic. A single stage process direct to hydrocarbon is possible, but a two-stage process, first to methanol, then using the well established 'Fischer-Troph' process to make a selectable molecular weight range of hydrocarbons may be the best route. To reach the ultimate efficiency of the process will require the dedicated skills of research chemists and chemical plant engineers. Careful thermodynamic design will reduce waste heat as far as possible in a large plant design.

If such a conversion process were 50% efficient, then with the electrical energy input described above for the 'large pilot plant' with a solar collection area of 10km x 10km, an output of 500,000 litres, or 3,000 'barrels' of refined petroleum-like hydrocarbon per hour could be expected.

It is estimated that the capital cost of globally replacing all existing oil extraction is around two trillion pounds (2000 billion). This is two years global oil revenue.

Such a broad paradigm shift away from the concept of pumping carbon fuels out of the ground, and towards synthesising them from atmospheric CO2 using solar energy, will eventually appeal to all oil companies.

When such solar fuel production plants are set up, the fuel they produce will be carbon neutral and essentially fully sustainable. Desert regions of the world will be effectively used. Aircraft will still fly, and cars will still run as they do today. Petrochemical industries can be sustained, and the oil companies can become sustainable. Atmospheric levels of CO2 can be stabilised, climate change and ocean rise averted.

The first stages in actively pursuing this target will be to set up a small research team to establish viable designs using CSP plant design and chemical engineering technology, and demonstrate on a large lab scale the viability of both the CO2 extraction, and the CO2 + H2 fuel synthesis. Expertise in oil refinery design would be a major bonus to speed up R&D in this area Once all main potential routes to the end are established, and the base level efficiency estimated, then pilot level plant design can start. Both Jordan and Egypt are already in the construction phase of suitable CSP power plants. A pilot plant with a 1 sq km solar collection area and a £100M-£300M price tag would produce fuel to keep one 747-400 jetliner in service (16 hrs per day). I estimate that this form of fuel production will be economically advantageous over conventional oil well extraction when the price of oil reaches $200 per barrel in today's terms.

Other economic factors such as carbon credits, and use of the bi-products such as oxygen could improve the economic balance.

Richard Monkhouse,

Jan 2006 - Feb 2008.

Patent applied for.