Battery energy storage systems (BESS) can contribute to reducing carbon emissions when optimized to align with grid decarbonization goals, but their effectiveness depends heavily on operational strategies, policy frameworks, and grid conditions. Here’s a breakdown of key mechanisms and challenges:
Emissions Reduction Mechanisms
- Time-shifting renewable energy:
BESS charges during periods of low carbon intensity (e.g., midday solar surplus) and discharges during high-intensity peaks (e.g., evening demand surges), displacing fossil-fuel generation. For example, California’s grid-scale batteries reduced emissions by 9.8 kg CO₂ per kWh of capacity after policy reforms prioritized marginal emissions signals. - Enabling renewable integration:
By storing excess solar and wind power, BESS mitigates curtailment and reduces reliance on gas/coal “peaker” plants. During the 2024 solar eclipse, California’s batteries prevented fossil-fuel use by discharging stored solar energy. - Grid services for efficiency:
- Frequency response: Batteries provide rapid grid stabilization, reducing the need for inefficient gas plant operation.
- Inertia management: Lowering inertia requirements (e.g., from 140 to 120 GVAs in GB) through BESS improves gas plant efficiency, reducing system-wide emissions.
- Arbitrage with carbon signals: When co-optimized for both price and carbon intensity (e.g., California’s SGIP program), BESS prioritizes discharging during high-margin-emissions hours.
Challenges and Risks
- Emissions increases in unregulated markets: In ERCOT (Texas), 92% of batteries increased grid emissions in 2023 due to profit-driven charging from fossil sources and discharging during low-emission periods. Similarly, PJM Interconnection saw coal displacing gas as BESS freed fossil capacity for energy markets.
- Efficiency losses: Lithium-ion batteries lose ~10-20% of energy in storage cycles, requiring surplus generation that may come from fossil sources without proper incentives.
- Policy dependency: Success stories like California’s SGIP program required regulatory reforms to incorporate marginal emissions signals. Absent such policies, BESS often increases emissions.
Regional Case Studies
| Region | Outcome | Key Driver |
|---|---|---|
| California | Net emissions reduction (9.8 kg CO₂/kWh) by 2022 | GHG-aware algorithms and 100% carbon-free electricity targets. |
| ERCOT | 92% of BESS increased emissions in 2023 | Lack of carbon pricing and reliance on arbitrage-only strategies. |
| GB | 1.4M tonnes CO₂ saved in 2024 (4% of power sector emissions) | Marginal carbon intensity targeting and inertia management reforms. |
Critical Success Factors
- Marginal emissions signals: Algorithms must prioritize grid regions and times where discharge most directly offsets fossil generation.
- Paired renewables: Solar-coupled BESS consistently reduce emissions, unlike standalone systems in fossil-heavy grids.
- Regulatory frameworks: Mandates like California’s GHG signal or the UK’s carbon intensity tracking ensure BESS aligns with decarbonization.
Without intentional design, BESS risks becoming a “grid tech” agnostic to emissions rather than a decarbonization tool. Policy and algorithm reforms are essential to unlock their full potential.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-do-battery-energy-storage-systems-contribute-to-reducing-carbon-emissions/
