A refinery is a complex and integrated system designed to separate and transform hydrocarbon molecules contained in crude oil into specified products for diverse final purposes. It may vary from a simple refinery that runs a basic physical separation of crude oil by distillation, to a complex one that can also perform a series of chemical reactions to convert petroleum into a wider array of products. This process configuration is determined by the variety of different crude oils that are to be used and target market products. These many processing options intend to enhance yields of specific products that meet that target market specifications. All refineries use significant quantities of heat and power. For economic reasons, they are designed to use any lesser cost residual energy form, in particular those that don' t match market standards, like refinery fuel gas, heavy fuel oil or coke produced in their own operations. Due to natural gas production associated with crude oil and environmental restrictions, many refineries have been adapted to include natural gas in their energy mix. But regularly, a typical refinery fuel supply is composed of 50 to 70% of refinery gas, petroleum coke (either from a coking unit or catalytic cracking regeneration) and other heavy oil by-products. On average, 10 to 20% of an equivalent barrel of crude is required as energy to refine the rest into products. Power demand may be augmented by external electrical energy supply or by self-generation. This is an economic and security option, because it reduces energy costs and guarantees operational continuity, making its operation independent of external power sources. Energy is the largest cash operating expense in any refinery ranging from at least 30 up to 60% total manageable costs.
There are nowadays approximately 700 refineries in the world, with an overall refining capacity around 85 million barrels a day. Most of these refineries and capacity lay in USA (almost 23% of the refineries and 22% of capacity) and Western and Central Europe (18% refineries with 18% of capacity). Asian Pacific countries together sum 27% of refineries and 29% of capacity. China and Japan alone respond for one third of the refineries and almost half of the region capacity. Most of the other countries have smaller numbers and capacity share. In general terms, the refining business is dominated by USA, Europe, East Asia and Latin America, which together account for almost 80% of global refineries and capacity.
The usual capacity of a refinery ranges from 1000 to almost 1000 000 bbl/day, with average size of 150 000 bbl/day, using something like 9% of its volume throughput as energy. They are normally integrated with logistics facilities, like an oil terminal with a harbor or a pipeline complex and some other industry, like a petrochemical, a power plant or any other energy demanding plant. Generally, refinery energy consumption is a function of its size and complexity, bigger and more complex plants tend to consume more energy per input barrel and in absolute terms, simple and small refineries consume less. And of course their CO 2 emissions follow the same pattern.
For the last 40 years, refineries have progressively increased their complexity, investing in processing units to upgrade oil products, reducing fuel oil yield and enhancing gasoline, kerosene and diesel type products yield, matching products to tighter quality standards, especially regarding environmental law. The energy conservation movement has made refineries around the world reduce their energy intensity, meaning that the average refinery nowadays requires 25% less energy to refine one barrel than the average one did four decades ago.
The trend over recent years has been towards more complex and energy intensive processing for many reasons. Existing oil reserves are depleting, enhancing competition for light and sweet crudes and at same time, pushing refiners to process cheaper heavy and sour crudes. On the way around, more rigid product standards especially related to pollution reduction, together with lesser quality crudes, concentrate emissions and hazardous components in the refinery, demand auxiliary processes to treat and dispose them. These factors together are leading to refineries demanding more energy in absolute figures, although they are more energy efficient in terms of productivity. Concerning most of the energy demand forecasts, petroleum will remain the main world's energy source for the next 50 years. But the greenhouse effect seems to be here to stay and law makers and governments are doing something about that, like emission restrictions for fuel end user over sulfur, nitrogen, particulates. And not to forget CO2, there is the Kyoto protocol and whatever instrument that replaces it.
Considering this path that refiners have followed, and previewing challenges for the future, energy conservation or energy efficiency activities will continue to be included with good management practices. Reasons? First of all, (the old and good reason): money! Energy saving is and will always be driven basically by return rate and cost reduction, either operational or investment. It will depend on energy prices, but remember that there should be extra gains! Whenever you accomplish any energy efficiency action there is a good chance that you will also be reducing some other operational expense, like water for cooling and of course water treatment costs and emission reduction when you burn less fuel. And when you demand less water, fuel, steam, you can postpone the investment for new facilities, and that means more money in hand, less interest rates to pay and more to receive. And you might also be helping to cope with environmental regulation. So, energy efficiency has been and still is, an important part of refinery management. Now we will discuss some ways and points of view of how to deal with it and make it valuable and practicable.
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