OTHER THERMAL

Power generation based on thermal sources is nowadays the main support for the functioning of the Angolan electrical system. The lower investment and quicker installation when compared to hydro, has allowed to respond to the growing demand, although to an insufficient extent. However, the use of diesel to supply these plants results in high operating costs, which are not yet reflected in the rates charged to electric customers.
The startup of the natural gas terminal in Soyo allows the access of the electrical system to a lower cost fuel with lower emissions: natural gas. Until 2017, the main growth in the installed thermal generation in the country will come from Soyo’s combined cycle power plant, with 720 MW.
It is expected that the gas will represent almost 50% of the installed thermal power by 2017 (graph below).
Strong investments in progress in hydroelectric generation and in transmission grids will significantly reduce the use of more expensive thermal sources. However, consumption growth and the variability of the hydrological regime of Angola will require not only the maintenance of many of these plants - to work in a more intermittent operation regime - but also the construction of new thermal capacity on the horizon of 2025.
Therefore, it is essential to identify and consider the most appropriate and competitive options for thermal generation in Angola, based on either natural gas or on other alternative fuels.

THERMAL POWER DISTRIBUTION PLANNED FOR 2017 BY TECHNOLOGY

THERMAL GENERATION INSTALLED IN 2017 - BASED ON THE ACTION PLAN

Competitiveness and interest in the different thermal options result from the cost structure:

• On the one hand, the variable cost of operation - depending on the primary source, its cost and efficiency of conversion into electricity;
• On the other hand, the fixed cost and flexible of the conversion technology.

The graph in below shows the subsidized and the unsubsidized prices of the major primary sources available - as published by the Government in 2014 - and also the viable sources on the horizon of 2025. Soyo’s natural gas, delivered in a gaseous state at the output of the terminal Angola LNG, due to the existing contractual arrangement, is the most economical heat source.
Coke resulting from the new refinery and coal - considering international prices - is the second most economical primary sources after Soyo’s gas.  However, the high fixed costs, reduced operating flexibility as well as the reduced efficiency of conversion make this alternative more expensive than
the gas and less suitable for a system with a high proportion of hydro. It is recognized however that the coke that will be produced can be used for self-consumption in the new refinery and/or local supply.

VARIABLE COST OF DIFFERENT TYPES OF PRIMARY ENERGY

The LNG produced by the Angola LNG terminal is currently the most economical alternative to the existing open cycle turbines, foreseeing the  conversion of about 300 MW on the horizon of 2025. The conversion of all turbines may not be justified due to the low utilization of some of those and due to the necessary investments.
The heavy fuel oil (HFO) is a cost competitive alternative - which Angola produces in greater quantity than it consumes - that can be used in about 400 MW of medium-speed diesel engines installed in Angola (as indicated in the following table). The need for investment in the pre-processing and heating of the fuel oil decreases the interest of conversion when the usage of these plants is small. However, in the case of existing plants with space and where the conversion and a logistics supply of fuel oil is possible, the conversion has a quick return, which is why it was considered.
Diesel, LPG and JetB are currently expensive alternatives for electricity generation. The ease of storage and greater availability make the diesel the most viable alternative to stock or “backup” solutions, as well as to supply the isolated systems on the horizon of 2025. Moreover, the GPL, which will be produced in Soyo’s terminal, may represent a significant cost reduction for the country and can be an alternative to diesel for these stock or “backup” solutions in turbines. Finally, the use of JetB in the sector, due to its high price, should be eliminated.

ELECTRICITY PRODUCTION TECHNOLOGIES