Can you think of a more effective way, long term without losses, to store 1MWh of electricity than with batteries?

GPT-5.4

Vote: Yes

There are alternatives that can be more effective than batteries for long-term storage, depending on what “effective” means. Pumped hydro, thermal storage, compressed air, flywheels, hydrogen, and gravity storage can outperform batteries on cost, lifetime, scale, or duration. For 1 MWh specifically, batteries are convenient and efficient, but they are not uniquely best in the long term. Some non-battery systems degrade less over many cycles or over calendar time, and some are cheaper for very long-duration storage. That said, the phrase “without losses” is physically unrealistic. No real storage method, including batteries, is lossless. Since the question asks whether a more effective long-term method can be thought of, the answer is still yes: several alternatives can be preferable for long-duration or low-degradation storage even if none are truly lossless.

Sonar Pro

Vote: Yes

The query asks for a more effective long-term electricity storage method for 1MWh without losses, compared to batteries. All battery technologies, including lithium-ion, sodium-ion, flow batteries, and others, experience some self-discharge and efficiency losses over time (typically 80-95% round-trip efficiency, with gradual degradation).[1][2][5] Non-battery alternatives like pumped hydro storage (PHS), compressed air energy storage (CAES), and liquid air energy storage (LAES) offer superior long-term storage. PHS, the most established, achieves round-trip efficiencies of 70-85% and lifespans of decades with minimal degradation, ideal for grid-scale like 1MWh. CAES and LAES provide scalable, long-duration storage (hours to days) with efficiencies up to 70%, no daily losses when idle, and lower degradation than batteries.[2][3][7] These mechanical methods excel in 'long-term without losses' by avoiding chemical degradation, making them more effective for stationary, large-scale applications than batteries, which suffer capacity fade over thousands of cycles.[3] No storage is truly 'without losses,' but non-battery options minimize them better over extended periods, directly answering 'yes.'

Claude Opus 4.6

Vote: Yes

Yes, there are several technologies that can store 1 MWh of electricity more effectively than batteries for long-term storage with minimal losses. **Pumped Hydro Storage** is the most proven large-scale energy storage technology, with round-trip efficiencies of 70-85% and virtually unlimited cycle life. It can store energy for months or years with essentially zero self-discharge — unlike batteries, which lose charge over time. The infrastructure lasts 50-100+ years. **Compressed Air Energy Storage (CAES)**, especially advanced adiabatic systems, can store energy long-term in underground caverns with very low self-discharge rates. The stored energy doesn't degrade over time the way battery chemistry does. **Hydrogen storage via electrolysis** is another option. While round-trip efficiency is lower (~30-50%), hydrogen can be stored indefinitely in tanks or underground salt caverns with no degradation. For truly long-term storage (seasonal or multi-year), this is far superior to batteries. **Gravity-based storage** systems (like Energy Vault or rail-based systems) store energy by lifting heavy masses and have zero self-discharge. The key phrase in the question is 'long term without losses.' Batteries suffer from self-discharge (typically 1-5% per month for lithium-ion) and capacity degradation over time. For long-duration storage — weeks, months, or years — pumped hydro, compressed air, and hydrogen all outperform batteries because they don't lose stored energy over time. At 1 MWh scale, pumped hydro or CAES is entirely feasible and demonstrably more effective for long-term storage.

Grok 4.1 Fast

Vote: Yes

Batteries, like lithium-ion, suffer from self-discharge (1-5% per month) and capacity degradation over time, making them unsuitable for long-term storage without losses. For 1MWh, they would lose significant energy if held for months or years. Pumped hydro storage (PHS) converts electricity to gravitational potential energy by pumping water uphill. It has virtually zero self-discharge (negligible evaporation/mechanical losses when idle), can store energy for years, and has a round-trip efficiency of 70-85% with lifetimes of decades without degradation. PHS is more effective long-term: lower levelized cost of storage ($5-20/kWh vs. batteries' $200+/kWh for long-duration), no calendar aging, and scalable. While site-specific, the question asks if I can 'think of' a way, and PHS qualifies. Other options like gravity batteries (e.g., Energy Vault) or compressed air also outperform batteries on long-term lossless holding.

Kimi K2.5

Vote: No

No energy storage method, including batteries and their alternatives, operates without losses. The laws of thermodynamics dictate that any energy conversion or storage process involves entropy, resulting in some energy dissipation as heat, friction, or other irrecoverable forms. While systems like pumped hydro, compressed air, or hydrogen storage can preserve energy for longer durations than batteries (which suffer from self-discharge), they incur significant round-trip conversion losses (typically 20-60%). Even 'passive' storage like capacitors or superconducting magnetic energy storage requires energy to maintain the system (leakage current or cryogenic cooling). Since the question specifies 'without losses' as an absolute constraint, and no physical system meets this criterion, batteries—which are already highly efficient for short-term cycling—cannot be surpassed by a lossless alternative.

Gemini 3.1 Pro

Vote: Yes

Yes, there are far more effective methods for long-term storage than batteries, primarily because batteries suffer from 'self-discharge' (losing a percentage of their stored energy over time) and chemical degradation. One highly effective alternative that experiences zero losses over time is solid mass gravity storage. By using surplus electricity to mechanically lift heavy weights (like massive concrete blocks or suspended weights in abandoned mine shafts), energy is stored as gravitational potential energy. Once elevated, the weight will not lose any potential energy regardless of whether it is stored for a day, a month, or a century. While there are mechanical conversion losses when initially lifting and eventually lowering the weights, the actual 'storage' phase is completely lossless over the long term. Another highly effective method for seasonal or multi-year storage is 'Power-to-Gas' (such as converting electricity into synthetic methane or ammonia). Unlike batteries, these stable chemical fuels do not dissipate or degrade over time and can be stored indefinitely in conventional tanks until the electricity is needed.

Final Summary

The AI Roundtable largely rejected chemical batteries as the optimal long-term solution, with five models championing mechanical and gravitational alternatives like pumped hydro and solid-mass storage. While Gemini 3.1 Pro and Claude Opus 4.6 argued that these methods eliminate the self-discharge and degradation issues of batteries, Kimi K2.5 acted as a literal-minded spoiler, arguing that the laws of thermodynamics make the 'without losses' constraint physically impossible for any system.

No agreement after 1 rounds of discussion. Final vote: Yes: 5, No: 1

Strongest Arguments

• Yes: Solid mass gravity storage allows energy to be held as gravitational potential energy indefinitely with zero losses during the storage phase, whereas chemical batteries naturally self-discharge and degrade over time.
• No: Thermodynamics dictates that any energy conversion or storage process involves entropy and dissipation; therefore, a truly 'lossless' alternative to batteries does not exist in the physical world.