2024-10-13-ITIF-为什么风能和太阳能需要天然气_一种现实的变化方法（英）_42页_1mb

Robin Gaster's report analyzes the challenges of integrating variable renewable energy (VRE) into the grid and proposes a phased transition, with natural gas playing a key role as a bridge technology for decades. The core argument is that VRE variability requires reliable backup, best provided by natural gas initially, not long-duration storage technologies like hydrogen.

1. Core Problem:

• VRE (wind/solar) replaces consistently dispatchable fossil fuels, introducing variability and unpredictability.
• Current storage (batteries, hydrogen) cannot handle seasonal or annual VRE deficits that emerge as penetration increases.
• A realistic, phased approach is needed, with natural gas bridging the gap.

2. Phases of Transition:

• Phase I (<~40% VRE): VRE variability manageable with existing dispatchables (including gas replacement of coal).
• Phase II (~40-80% VRE): Gas transitions from baseload to contingency/peaking role, becoming critical backup. Existing gas plants (CCGTs and peakers) provide the necessary insurance.
• Phase III (>~80% VRE): Requires VLDES or gas with carbon capture to fill the remaining deficit gap.

3. Natural Gas Backup:

• Gas offers dispatchability, fast ramping, and massive scale via existing infrastructure.
• During Phase II, CCGTs provide most generation but evolve to offer more peak capacity (like peakers), operating far below full load factors (avg. 57%) which provides existing buffer capacity.
• Gas + batteries is a powerful combination, with batteries aiding grid flexibility and gas covering longer-term/lower-penetration deficits.

4. Critique of Long-Duration Storage (VLDES):

• All major VLDES technologies tested (hydrogen, compressed air, advanced pumped hydro) suffer from:
  • Low efficiency: Especially hydrogen (~40% round-trip efficiency).
  • High cost: Dominated by input electricity cost/efficiency (hydrogen is expensive even with subsidies).
  • Scalability issues: PHS faces environmental/regulatory barriers; geological storage (salt caverns/aquifers) is limited and costly.
  • Environmental Concerns: Leaks (especially hydrogen), land use (PHS), water use (hydrogen production).
• VLDES deployment is very long-term, making near-term subsidies counterproductive.

5. Policy Recommendations:

• Focus R&D Appropriately: Target technologies most viable in the long run for Phases II/III, not unrealistic short-term fixes.
• Staggered Rollout: Policy should reflect Phases I through III, funding phased solutions.
• Regulatory Focus: Mandate contingency reserves (VRE insurance) and pass costs to consumers gradually, avoiding expensive market reliance during transition.
• Government Leadership: Establish a dedicated DOE office to coordinate VRE variability research, modeling, and international collaboration.