Fuel Switching

Fuel switching is the substitution of one type of fuel for another, especially the use of a more environmentally friendly fuel as a source of energy in place of a less environmentally friendly fuel. 

The capability to use substitute energy sources means that the combustors (e.g., boilers, furnaces, ovens, and blast furnaces) of a facility had the machinery or equipment either in place or available for installation so that substitutions could actually have been introduced within a specific time period without extensive modifications. 

Fuel-switching capability does not depend on the relative prices of energy sources it depends only on the characteristics of the equipment, environmental issues, and legal constraints. 

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Fuel switch. The choice of fuel used in furnaces and steam boilers has a major effect on the gaseous utility waste from products of combustion. For example, a switch from coal to natural gas in a steam boiler can lead to a reduction in carbon dioxide emissions of typically 40 percent for the same heat released. This results from the lower carbon content of natural gas. In addition, it is likely that a switch from coal to natural gas also will lead to a considerable reduction in both SO, and NO, emissions, as we shall discuss later. 

Such a fuel switch, while being desirable in reducing emissions, might be expensive. If the problem is SO, and NO, emissions, there are other ways to combat these, which will be dealt with in the next chapter. 

Fuel switch. Fuel switch from, say, coal to natural gas reduces the CO2 emissions for the same heat release because of the lower carbon content of natural gas. 

Fuel switch. Switching to a low-sulfur fuel is an obvious solution. 

Fuel switch. Since formation is fuel-dependent, switching fuel can reduce formation. The general trend is that from solid to liquid to gaseous fuel, the formation decreases. However, it should be emphasized again that this is also very much dependent on the combustion device. 

Only a small portion of motor fuel needs could be satisfied if truly large-scale alcohol—gasoline blending or fuel switching occurred via transition to fuel-flexible vehicles and ultimately to neat alcohol-fueled vehicles (132). 

When the Clean Air Act of 1990 was signed into law, electric utiUties were requited to estabUsh plans and initiate projects to comply with that Act s Tide IV. Each utihty had to evaluate how the various commercial and emerging clean coal systems fit into the utiUty s technical and business environment resulting in strategies to utilize fuel switching and wet throwaway FGD processes almost exclusively (38,85,86). 

Sun eyors from ihe Emdronmenial Protection Agency inspect the tampering and fuel switching. tCorbis Corporation)... 

For a given energy consumption, fuel change is the only way to reduce C02 and SO emissions at source. Fuel switch from, say, coal to natural gas reduces the C02 emissions for the same heat release because of the lower carbon content of natural gas. Fuel change can also be useful for reducing NO, emissions. Once emissions have been minimized at source, then treatment can be considered to solve any residual problems. 

More reliable and durable instrumentation. Temperature monitoring instrumentation needs to have life extensions beyond current 30 to 45 days. Furthermore, automated on-line feed (for fuel switching purposes) and on-line product analysis instrumentation are needed. 

Hagey, G., Marinetti, D., Mueller, E.A., Status of fuel cell system development/Commercialisation and future systems energy, environmental, and economic benefits, pre-prints International Conference, Next Generation Technologies for Efficient Energy End Uses and Fuel Switching, Dortmund, 7-9. April 1992. 

Figure 1 Prognosis of the greenhouse gas emissions caused by the European Union up to 2030 [2]. De-facto emission so far showing a reduction with a minimum in the year 2000 - mainly owing to fuel switching from coal and oil to natural gas. Beyond 2000 up to 2030 a substantial increase is expected - requiring new measures and initiatives.

However, Norway has taken an extreme position regarding natural gas Despite its position as one of the world s largest gas exporters Norway has no tradition for using natural gas. Neither is fuel switching an issue because of the predominance of Norwegian hydropower (99.4%). So far only 1% of its produced gas is consumed domestically - mainly LNG produced by a methanol plant at Tjeldbergodden (refer section 6.3). The outlook is that only limited amounts of natural gas will be introduced to the Norwegian infrastructure - basically LNG. 

In Denmark, the integrated gas company, has designed its back-up and storage capacity to be able to continue gas supplies to the non-interruptible market with no alternative fuel switching capacity in case of a disruption of one of the two offshore gas pipelines supplying gas to Denmark. 

A maximum 10% of auctioning would make around 210 Mt C02/year available through auctions, out of a total allocated of 2100 Mt C02. The overall shortfall - to be met through emissions abatement (e.g. fuel switching end-use efficiency in the power sector) and international purchase - would then still be only around 100 Mt C02/year, close to the revealed surplus in 2005 and much smaller than the lowest estimates of the total supply of Kyoto project credits. 

But, there are limits to potential energy efficiency improvements and many fuel switching options more innovative solutions will be needed in the longer term if the current goals are to be met. 

Figure 4. Annualized cost/fuel switching comparison...

Equation 51 indicates that the most obvious way to control fuel NO is by reducing the bound nitrogen content in the fuel. This reduction can be accomplished by fuel switching (from heavy oil or coal to light oil or gas) or by denitrification. Unfortunately, fuel availability limits both approaches. 

In general, fuel switching is currently the cheapest option at the current price difference of 10/ton between high-sulfur and low-sulfur coals. However, as low-sulfur coal prices increase, this will become less economical. Dry processes are the next most economical option, but they may not be able to meet emission control standards. The various types of scrubber have broadly similar costs, and the choice will depend on the specific plant under consideration. It appears from Table 4 that advanced combustion technologies such as integrated... 

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