Are gas turbines losing their market share to gas engines? This question does not seem to leave the lips of power plant industry players. Gas turbines have conventionally been the sole technology of choice for larger sized heat and power projects. If you ask any industry expert, the situation could slowly but notably be changing, owing to the greater flexibility exhibited by engines. As the tradition in power plants is tested, we compare the two types of power plants ( gas turbine and gas engine), giving the pros and cons of each.
Gas Engine Power Plant
This refers to an internal combustion engine that relies on fuels such as natural gas, blast furnace gas and producer gas. This equipment is often associated with Dr. Otto, the famous scientist who improved the original work of the Frenchman called Lenoir. The gas engine is based on the Otto Cycle. Unlike the diesel cycle, the Otto Cycle does not undergo what is referred to as auto-ignition. Instead, a spark plug initiates the ignition of the air-fuel mixture.
Fig 1: GE’s Gas Engine
Like a motorcar engine, a gas engine power plant is characterized by a four-stroke cycle. The major difference is that the fuel is natural gas or others. Another difference would be that the engine runs constantly once the operator has set the required capacity. The engine connects to a generator for electricity generation. Similar to a car engine, this engine warms up and produces waste heat. The sources of the heat include:
- Exhaust gas
- Gas mixture production
- Hot lubricating oil
In the power plant setting, you will find several gas engines interconnected to form generating sets. However, every engine connects to its shaft that connects to an electric generator. The sets are available in standardized sizes of up to 20 MW. Other technologies may encounter higher costs and problems when required to adjust load to actual demand, but engine power plants play this role very effectively. Even if the power plant carries more than 20 such engines, starting and stopping them within minutes to match demand is not an issue. Modularity and high cost-efficiency give gas engines provide an optimal solution for steady power requirements in any place. You can easily install a small or medium sized power plant on the roof or in the basement. You could even containerize it. These and other characteristics are summarized below.
Turbine Gas Power Plants
A gas turbine, the brain of the power plant, is a combustion engine that converts liquid fuels, especially natural gas, into mechanical energy. This energy powers a generator that in turn produces electricity.
Fig. 1: Industrial Gas Turbine
Within the gas turbine, there is a fuel-air mixture being heated at extremely high temperatures. This causes the turbine blades to spin fast. The market for gas turbines is growing steadily, the prediction being that the trend will continue into 2020. It is easy to understand why this is the case if you look at the advantages outlined below.
For installations in areas of high ambient temperature, TIAC installations often come in handy.
Gas Turbine or Gas Engine?
Every developer of a power generation project must grapple with this question. Reciprocating engines are usually the technology of choice for small projects, but larger projects suit turbine gas power plants. The problem arises when you have to choose for power plants in between. At ARANER, we can help select the best-fit solution based on specific project attributes. You can always rely on our technological support for gas turbine based power plants, for instance turbine inlet air cooling (TIAC) solutions.