In this context, global technology group Wärtsilä conducted in-depth studies that analyses the economic impact of the various gas-to-power strategies available to Senegal. Two very different technologies are competing to meet the country’s gas-to-power ambitions, namely, combined-cycle gas turbines (CCGT) and gas engines – internal combustion engines (ICE).
These studies have revealed very significant system cost differences between the two main gas-to-power technologies the country is currently considering. Contrary to prevailing beliefs, gas engines are in fact much better suited than combined cycle gas turbines to harness power from Senegal’s new gas resources cost-effectively, the study reveals. Total cost differences between the two technologies could reach as much as $480 million until 2035 depending on scenarios.
Two Competing and Very Different Technologies
The state-of-the-art energy mix models developed by Wärtsilä, which builds customized energy scenarios to identify the cost optimal way to deliver new generation capacity for a specific country, shows that ICE and CCGT technologies present significant cost differences for the gas-to-power newbuild program running to 2035.
Although these two technologies are equally proven and reliable, they are very different in terms of the profiles in which they can operate. CCGT is a technology that has been developed for the interconnected European electricity markets, where it can function at 90% load factor at all times. On the other hand, flexible ICE technology can operate efficiently in all operating profiles, and seamlessly adapt itself to any other generation technologies that will make up the country’s energy mix.
In particular, our study reveals that when operating in an electricity network of limited size such as Senegal’s 1GW national grid, relying on CCGTs to significantly expand the network capacity would be extremely costly in all possible scenarios.
Cost differences between the technologies are explained by a number of factors. First of all, hot climates negatively impact the output of gas turbines more than it does that of gas engines.
Secondly, thanks to Senegal’s anticipated access to cheap domestic gas, the operating costs become less impactful than the investment costs. In other words, because low gas prices decrease operating costs, it is financially sound for the country to rely on ICE power plants, which are less expensive to build.
Technology modularity also plays a key role. Senegal is expected to require an extra 60-80 MW of generation capacity each year to be able to meet the increasing demand. This is much lower than the capacity of typical CCGTs plants which averages 300-400 MW that must be built in one go, leading to unnecessary expenditure. Engine power plants, on the other hand, are modular, which means they can be built exactly as and when the country needs them, and further extended when required.
The numbers at play are significant. The model shows that if Senegal chooses to favor CCGT plants at the expense of ICE-gas, it will lead to as much as $240 million of extra cost for the system by 2035. The cost difference between the technologies can even increase to $350 million in favor of ICE technology if Senegal also chooses to build new renewable energy capacity within the next decade.
Risk-Managing Potential Gas Infrastructure Delays
The development of gas infrastructure is a complex and lengthy endeavor. Program delays are not uncommon, causing gas supply disruptions that will have a huge financial impact on the operation of CCGT plants.
Nigeria knows something about that. Only last year, significant gas supply issues have caused shutdowns at some of the country’s largest gas turbine power plants. Because gas turbines operate on a continuous combustion process, they require a constant supply of gas and a stable dispatched load to generate consistent power output. If the supply is disrupted, shutdowns occur, putting a great strain on the overall system. ICE-gas plants on the other hand are designed to adjust their operational profile over time and increase system flexibility, and because of their flexible operating profile, they were able to maintain a much higher level of availability
The study took a deep dive to analyze the financial impact of two years delay in the gas infrastructure program. It demonstrates that if the country decides to invest into gas engines, the cost of gas delay would be $550 million, whereas a system dominated by CCGTs would lead to a staggering $770 million in extra cost.
Whichever way you look at it, new ICE-gas generation capacity will minimize the total cost of electricity in Senegal in all possible scenarios. If Senegal is to meet electricity demand growth in a cost-optimal way, at least 300 MW of new ICE-gas capacity will be required by 2026.