Briefly, it works as follows:
- in the first year of the scheme an industry receives from the government an aggregate allocation of carbon emissions certificates (CEFs) - representing the industry's total allowable emissions for the period;
- for that year each business in the industry is allocated a portion of the industry's aggregate allocation - representing the business's total allowable emissions for the period;
- if during that year a business needs to emit more than the allocation given to it, it must either a) buy CEFs from others in the industry, or b) become more energy efficient by say, investing in plant and machinery for improved energy efficiency.
- investing in lighter aircraft so that fuel consumption is reduced;
- investing in more efficient aero-engines as and when they become available;
- use exempt fuels (if any) (adapting or changing engines, if necessary).
- save by flying faster;
- save on aero-fuels;
- save by selling-off their surplus CEFs!