Desalination can beat batteries for excess energy
Using surplus solar and wind power for energy-intensive processes like seawater desalination is proposed as a cheaper alternative to large battery installations, especially in arid regions that already need fresh water. Commenters weigh the benefits and limits of “flexible demand” industries—such as desal, aluminum smelting, hydrogen production, and EV charging—that can ramp up when electricity is cheap and idle when it’s scarce, effectively acting as a form of energy storage. The debate broadens into whether such strategies, combined with renewables, can meaningfully decarbonize power grids, or whether large-scale nuclear and fossil baseload remain necessary.
Desalination vs Batteries as Sinks for Excess Energy
- Desalination is framed as a “productive” way to absorb surplus renewable power, versus storing it in batteries or mining crypto.
- Key idea: oversize desal capacity, run harder when electricity is cheap/abundant, back off when the grid is tight.
- Some argue desal “helps” net‑zero by providing economic use for spring overproduction; others say this only works on hybrid (fossil+renewable) grids, not fully renewable ones with flatter marginal costs.
Economics and Capital Utilization
- Major trade‑off: higher desal CapEx and lower utilization vs. buying batteries.
- Example from Carlsbad plant: capital cost dominates; energy is ~1/3 of water cost. Running part‑time can double per‑ton water cost, potentially overwhelming savings from cheap/free electricity.
- One commenter’s back‑of‑envelope: desal as “battery” can be 10–100× more expensive than dedicated batteries, though this is contested.
- Using tanks as “freshwater storage” is cheap; question is whether extra desal capacity + tanks beats grid batteries. Unclear from thread.
Flexible Demand and “Virtual Batteries”
- Broader theme: shifting demand to match variable supply is often cheaper than storage.
- Industrial examples: aluminum smelters experimenting with ±25% load over 48 hours; some see this as multi‑GWh “virtual storage.”
- Constraints: many industrial processes want near‑100% utilization and dislike shutdowns; capital sits idle when offline.
- Residential/commercial demand response already used for A/C, water heating, lighting, EV charging, often orchestrated via time‑of‑use or real‑time pricing.
Renewables vs Nuclear for Decarbonization
- One camp: only nuclear (and geothermal) can realistically provide low‑carbon baseload and enable net‑zero; renewables need overbuild plus storage and still imply hybrid grids.
- Other camp: nuclear costs/timelines have spiraled, while solar/wind (and increasingly batteries) are on factory‑scale learning curves and are being added far faster in practice.
- Disagreement over why nuclear is expensive (regulation vs inherent complexity) and whether SMR/MSR designs will change this. No consensus.
Other “Excess Energy” Sinks
- Suggestions: hydrogen (for ammonia, storage), though round‑trip losses and electrolysis issues are high versus reverse osmosis.
- EVs as distributed storage via managed charging/VPPs; debate over battery wear vs falling cell costs.
- General agreement: use cheap surplus power directly where possible; reserve batteries for what cannot be time‑shifted.