According to the Handbook of Energy and Economic Statistics of Indonesia, the total installed capacity of Geothermal Power Plants (PLTPB) stood at 2,130.70 MW in 2020.
This capacity has not been fully utilized due to several factors, such as efficiency, costs, and monthly electricity price uncertainty.
Geothermal power plants are considered a renewable energy source because the rate of heat extraction is low relative to the total geothermal heat reservoir; emissions generated are less than 122 kg of CO2 per megawatt-hour (MWh)—or one-eighth of the emissions produced by coal-fired power plants.
Geothermal power plant development involves drilling into geothermal areas to create wells that channel hot gas to drive a turbine connected to a generator. Geothermal fluid possesses high pressure capable of spinning the generator turbine after the steam undergoes a separation process.
Characteristics of Geothermal Power Plants
The operation of a geothermal power plant is similar to that of a conventional steam power plant (PLTU); the primary difference lies in the source of the steam fluid. While conventional steam power plants use fluid derived from coal, geothermal plants utilize heat sources from the Earth's interior.
If the fluid emerging at the surface is dry steam, it can be fed directly into the turbine; however, if the fluid exists in a two-phase state (a mixture of liquid and vapor), it must first be processed in a separator.
Advantages of Geothermal Power Plants
a. Environmentally Friendly
Geothermal energy is more environmentally friendly than fossil fuels. Geothermal power plants have a low carbon footprint.
Although this energy source does generate some pollution, the volume is significantly lower than that produced by fossil fuels.
b. Renewable Energy Source
Heat sources from within the Earth are replenished naturally and sustainably. Geothermal energy can endure as long as the Earth continues to rotate.
Global energy consumption stands at 15 terawatts—a figure far below the total potential energy available from geothermal sources. Although most reservoirs cannot currently be utilized, they remain under development by the energy industry.
Geothermal power plants are estimated to have a capacity ranging from 0.0035 to 2 terawatts.
c. Sustainable
Geothermal energy is a reliable source because it is always available for use. It simply requires extracting geothermal heat and converting it into steam.
Geothermal energy is effective for power generation—driving turbines—when fluid temperatures exceed 150°C. Because the ground retains heat better than the air, it can act as a heat sink or source when geothermal heat pumps are installed just two meters below the surface.
d. Reliable
Geothermal energy sources do not fluctuate like other energy sources. Consequently, electricity output can be predicted with a high degree of accuracy.
Furthermore, geothermal energy is a natural resource, so it does not require the intensive extraction processes associated with fossil fuels.
Disadvantages of Geothermal Power Plants
a. Greenhouse Gas Emissions
Despite the generally positive reputation of renewable energy sources, geothermal energy raises certain environmental concerns.
Extracting geothermal energy from the ground releases greenhouse gases such as hydrogen sulfide, carbon dioxide, methane, and ammonia. However, the volume of released gases is significantly lower than that produced by fossil fuels.
b. Risk of Depleting Geothermal Heat Sources
Geothermal energy carries the risk that the extraction site may cool down. In other words, the location could eventually run out of heat.
Heat energy from magma is the only source that remains untapped due to technological limitations; researchers are currently developing tools to harness this heat, which has existed for billions of years.
c. High Investment Costs
Another drawback of this system is the high cost of production. It requires drilling operations and the installation of the geothermal energy system.
d. Requires Dedicated Land
Finally, geothermal power plants require dedicated land for installation. This makes them unsuitable for implementation in major cities. Beyond land constraints, the permitting process is also time-consuming.
Geothermal power plants offer a renewable energy option since they harness heat from the earth, eliminating the need for extraction from reservoirs. However, they face challenges regarding land availability and high investment costs for households.
While geothermal energy is reliable, it cannot be utilized under all conditions.
Advantages of Solar Power Plants (PLTS) Compared to Geothermal Power Plants
Generating electricity from geothermal energy is no easy task. It involves various requirements and permits, such as land acquisition and difficulty in permits that are difficult to manage in densely populated major cities.
So, what is the solution? There is actually an alternative energy source perfectly suited for big-city conditions: it requires minimal land, involves fewer permitting hurdles, and enjoys government support.
Solar power plants (PLTS) offer a solution for alternative energy in major cities. This power source harnesses sunlight to generate energy.
a. Requires Only a Fraction of Sunlight
Solar energy requires only a small fraction of available sunlight to generate electricity. The U.S. Department of Energy states that 90 minutes of sunlight reaching the Earth's surface can generate enough power to meet a full year's worth of energy consumption.
b. Efficient
Beyond ease of implementation, solar power plants are becoming increasingly efficient thanks to technological advancements and battery storage systems. Rhone Resch, President of the Solar Energy Industries Association (SEIA), noted that the solar panel sector has grown by over 40% in the last eight years, driven by industrial and technological momentum.
Most solar panels have an efficiency rate of 15% to 20%, meaning they convert 15% to 20% of the absorbed sunlight into electricity. This contributes to a sustained reduction in costs.
Cheaper Costs
Solar panels are becoming more affordable. In its World Energy Outlook 2020 report, the International Energy Agency (IEA) confirmed that solar power schemes offer the most accessible form of electricity. A 2021 report by the IEA predicted that the demand for solar energy would continue to grow, positioning it to become a primary global energy source.
This is partly due to low operation and maintenance costs. While the initial investment may be high, the long-term economics are favorable because maintenance is simple and inexpensive.