The environmental impacts of diabatic Compressed Air Energy Storage (CAES) systems can be summarized as follows:
1. Fuel Use and Emissions
Diabatic CAES systems dissipate most of the heat generated during air compression to the atmosphere, which wastes energy and requires reheating the compressed air before expansion in turbines for power generation. This reheating is typically done by burning natural gas, resulting in:
- Consumption of about 0.4 kg of natural gas per kWh of electricity generated.
- Emission of roughly 200 g of CO2 per kWh produced.
- Overall energy recovery efficiency is relatively low, around 27-50%, due to these heat losses and fuel burning requirements.
Thus, while diabatic CAES reduces fuel use and emissions significantly compared to traditional combustion turbines—using about 67% less fuel than them—it still depends on natural gas combustion, which compromises some ecological benefits and leads to CO2 emissions.
2. Heat Dissipation and Efficiency Losses
The loss of heat to the environment during the compression phase means energy is wasted, requiring additional fuel input for reheating during energy recovery. This inefficiency translates to increased fuel consumption and associated greenhouse gas emissions compared to isothermal or adiabatic CAES systems, which capture and reuse compression heat.
3. Site-Specific Environmental Concerns
- Most diabatic CAES systems store compressed air in underground caverns, which can involve extensive geological excavation or use of existing formations like natural caverns or mines.
- Excavation and cavern preparation involve environmental disruption, land use, and potential impacts on local geology and ecosystems.
- Use of pressure vessels is an alternative but may be cost-prohibitive and have manufacturing impacts.
- Such environmental impacts are generally lower than pumped hydropower storage, which requires large amounts of concrete and water use.
4. Potential for Decarbonization
- By replacing direct fossil fuel combustion for power generation with air expansion turbines and charging from renewable electricity, diabatic CAES helps reduce carbon emissions.
- Even with fuel burning for reheating, it achieves much lower emissions than traditional fossil generation and can be further improved with gas-scrubbing and technological advances.
Summary Table
| Environmental Impact Aspect | Details |
|---|---|
| Fuel Consumption | ~0.4 kg natural gas per kWh generated |
| CO2 Emissions | ~200 g CO2/kWh |
| Efficiency | 27-50%, limited by heat loss |
| Heat Loss | Significant heat dissipated during compression (wasted energy) |
| Storage Site Impacts | Geological excavation or use of underground caverns; less impactful than pumped hydropower |
| Decarbonization Potential | Reduced emissions vs. fossil combustion; relies on some natural gas for reheating |
| Technological Improvements | Heat recovery units can reduce losses and improve environmental footprint |
In conclusion, diabatic CAES systems provide a low-emission alternative to conventional gas turbines by using compressed air storage, but their environmental impact is tempered by natural gas use for reheating and the need for suitable geological sites for air storage. Improvements in heat recovery and site selection can further mitigate environmental effects.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-environmental-impacts-of-diabatic-caes-systems/
