The abnormal weather caused by global warming, such as heavy rain, threatens our daily lives. Therefore, it has been a long time since the whole society has tried to reduce the emissions of greenhouse gases such as CO2 and aim for carbon neutrality. However, many readers may not have a clear idea of how our lives will change in this process.
For example, how do we use electricity that is produced in different ways? To achieve carbon neutrality, we need to increase the use of renewable energy (RE) derived from natural sources. This is because RE does not emit CO2 when generating electricity. However, RE has a weakness, and it is not as simple as just increasing it. The biggest weakness is that it is unstable. Variable RE such as solar and wind power depends on the natural conditions at the time, and it is difficult to expect those type of RE to supply power stably. As a result, unexpected power blackout may occur and affect our lives.
Therefore, the concept of "energy mix" becomes important. This is a method of supplying electricity by combining various power generation methods, such as hydro, solar, wind, geothermal, thermal, and nuclear. By utilizing the strengths and compensating for the weaknesses of each method, we can supply electricity stably while reducing CO2 emissions. The Japanese government's "6th strategic Energy Plan" in 2021 also advocates the energy mix, and proposes an ambitious plan to increase RE to nearly 40% of the total.
This time, we focus on geothermal power generation among RE. It is being developed in countries located in volcanic zones, such as the United States, Indonesia, and Japan, but there are some challenges for full-scale introduction and popularization. To solve these challenges, we asked engineers and salesperson to talk about the project that utilizes the knowledge of both hardware such as generating equipment and the power of digital.
The potential of promising renewable energy source of geothermal power generation?
Geothermal power generation is RE that uses the heat of the earth, as the name suggests. Rainwater that seeps into the ground is heated by magma deep underground and becomes steam. Geothermal power generation uses this steam to rotate a turbine generator and produce electricity. The heat of magma is almost permanent. And rainfall is also repeated. This is why geothermal energy is expected as an energy source that can be supplied permanently. In addition, it is a power generation method that can contribute to carbon neutrality because it does not use fossil fuels and emits very little CO2.
As with other sources of RE, CO2 emissions from geothermal power generation are extremely low.
As the introduction of RE progresses toward carbon neutrality, low-cost and stable power sources that can generate electricity regardless of day and night have a large presence. Geothermal power generation is one of them, but how much expectation is there for geothermal power generation and what are the current challenges? We asked Ms. Mogi, who is in charge of sales at Toshiba Energy Systems, about the situation.
"Geothermal power generation is being developed in countries located in the Pacific Rim volcanic zone. Geothermal resources are exposed in volcanic zones, and the amount of resources is dominated by the United States, Indonesia, and Japan. However, we have not been able to fully utilize the potential of geothermal resources because of the challenges such as the risk of unsuccessful drilling, the time and cost required for geothermal resource exploration, and the various protection regulations such as the Natural Parks Law and the Hot Springs Law that make it difficult to construct power plants.
In addition, there are also challenges for existing geothermal power plants. It is difficult to secure and maintain the amount of geothermal steam generated from the ground, and it tends to decrease and deteriorate. In addition, the steam components contain sulfur and other substances that cause corrosion and deposition to equipment, resulting in deterioration of major equipment such as turbine generators. As a result, the power generation has to be stopped every time the equipment is in maintenance, and the calendar day utilization rate *1 is about 60%. How to improve the utilization rate of geothermal power plants is also an urgent issue." (Ms. Mogi)
*1 The ratio of the actual power generation amount to the power generation amount that would be obtained
if the target power generation equipment were to generate electricity at 100% output for a certain period of time.
