Zinc hybrid cathode long-duration battery storage, 4-12 h, levelised cost of storage

Lower limit in the input guards and in the replacement count.

Market range Exact by definition.

Unit multiplier in the CRF, the guards, the fade average and the Customized switch.

Market range Exact by definition.

Protects divisions against a zero denominator.

Market range Exact by definition.

Converts a percent to a fraction.

Market range Exact by definition.

Converts a fraction to a percent; also the 100 % upper limit of the discount-rate guard.

Market range Exact by definition.

kWh per MWh, to apply per-kWh costs to the MWh energy capacity.

Market range Exact by definition.

kW per MW, to apply the per-kW fixed O&M.

Market range Exact by definition.

Hours in a non-leap year: upper limit of the service-hours lever and basis of the capacity factor and average power.

Market range Exact by definition.

Halves the sum of beginning-of-life (1) and end-of-life (0.8) energy to get the average usable energy over one battery-module life.

Market range No independent range cited.

Code of the 2021 reference case in the 'Reference case' select.

Code of the 2030 projection case in the 'Reference case' select.

Shortest tabulated duration: lower limit of the duration slider and first interpolation knot.

Second interpolation knot.

Third interpolation knot.

Longest tabulated duration. Above 10 h every duration-dependent value is held at its 10 h figure and the out-of-sourced-domain flag is raised: no trend is extrapolated.

Upper limit of the duration slider. 10 to 12 h is an extrapolation zone, flagged on the page.

DC round-trip efficiency of the zinc hybrid cathode battery at 4 h. A maximum printed by the maker, in 20-80-20 % state-of-charge cycles: a best case, not a warranted average.

Market range PNNL-33283 Table 4.25 gives 75 % AC-AC for the 4 h nonflow composite, consistent with 81 % DC after the inverter and transformer chain.

DC round-trip efficiency of the zinc hybrid cathode battery at 6 h. A maximum printed by the maker, in 20-80-20 % state-of-charge cycles: a best case, not a warranted average.

Market range PNNL-33283 Table 4.25 gives 75 % AC-AC for the 4 h nonflow composite, consistent with 81 % DC after the inverter and transformer chain.

DC round-trip efficiency of the zinc hybrid cathode battery at 8 h. A maximum printed by the maker, in 20-80-20 % state-of-charge cycles: a best case, not a warranted average.

Market range PNNL-33283 Table 4.25 gives 75 % AC-AC for the 4 h nonflow composite, consistent with 81 % DC after the inverter and transformer chain.

DC round-trip efficiency of the zinc hybrid cathode battery at 10 h. A maximum printed by the maker, in 20-80-20 % state-of-charge cycles: a best case, not a warranted average.

Market range PNNL-33283 Table 4.25 gives 75 % AC-AC for the 4 h nonflow composite, consistent with 81 % DC after the inverter and transformer chain.

One-way efficiency of the inverter and, separately, of the transformer.

Market range No independent range cited.

Number of one-way conversion passes in a round trip (inverter and transformer, in and out).

Independent check of the efficiency chain: PNNL's composite AC-AC efficiency comes from Richey 2021, not from the Eos 2026 datasheet used by the model.

Rest after each charge and each discharge at 4 h, in the PNNL cycle-count formula (Eq. 2).

Rest after each charge and each discharge at 6 h, in the PNNL cycle-count formula (Eq. 2).

Rest after each charge and each discharge at 8 h, in the PNNL cycle-count formula (Eq. 2).

Rest after each charge and each discharge at 10 h, in the PNNL cycle-count formula (Eq. 2).

Two rests per cycle, one after charge and one after discharge.

Share of nameplate energy used in each cycle. Fixed, because the cycle life is only sourced at this depth.

Market range No independent range cited.

Cap on cycling: 365 equivalent full cycles a year, i.e. 456.25 cycles at 80 % DOD.

Usable energy at the end of a battery-module life, as a share of the beginning-of-life energy. With the linear decline it gives an average of 90 %.

Market range No independent range cited.

Cycles before the battery modules reach end of life. Medium evidence: the PNNL text on p.56 mentions 500 cycles for zinc-bromine nonflow while Table 4.26 prints 5,000; the table is kept, and the contradiction is stated here.

Market range PNNL p.56 text: 500 cycles (inconsistent with Table 4.26).

Calendar life of the battery modules: the module life is the shorter of cycle life / cycles a year and this value.

Market range Eos Indensity Core datasheet: expected life 25 years (system, maker claim).

All-in total installed cost of a 10 MW zinc nonflow system at 4 h, 2021 USD: battery modules, balance of system, power conversion, controls, system integration, EPC, project development and grid integration.

Market range PNNL-33283 Table 4.17-4.18 nonflow range 291-445 $/kWh across sizes, durations and years.

All-in total installed cost of a 10 MW zinc nonflow system at 6 h, 2021 USD: battery modules, balance of system, power conversion, controls, system integration, EPC, project development and grid integration.

Market range PNNL-33283 Table 4.17-4.18 nonflow range 291-445 $/kWh across sizes, durations and years.

All-in total installed cost of a 10 MW zinc nonflow system at 8 h, 2021 USD: battery modules, balance of system, power conversion, controls, system integration, EPC, project development and grid integration.

Market range PNNL-33283 Table 4.17-4.18 nonflow range 291-445 $/kWh across sizes, durations and years.

All-in total installed cost of a 10 MW zinc nonflow system at 10 h, 2021 USD: battery modules, balance of system, power conversion, controls, system integration, EPC, project development and grid integration.

Market range PNNL-33283 Table 4.17-4.18 nonflow range 291-445 $/kWh across sizes, durations and years.

Small-system anchor of the size law (1 MW against 10 MW at the same 4 h duration).

Projected 2030 all-in installed cost of a 10 MW zinc nonflow system at 4 h, expressed by PNNL in 2021 USD. A projection, hence medium evidence.

Projected 2030 all-in installed cost of a 10 MW zinc nonflow system at 6 h, expressed by PNNL in 2021 USD. A projection, hence medium evidence.

Projected 2030 all-in installed cost of a 10 MW zinc nonflow system at 8 h, expressed by PNNL in 2021 USD. A projection, hence medium evidence.

Projected 2030 all-in installed cost of a 10 MW zinc nonflow system at 10 h, expressed by PNNL in 2021 USD. A projection, hence medium evidence.

Cost of the DC storage block (battery modules) paid again at each module replacement, 2021 case.

Storage-block cost at each replacement, 2030 projection case.

Fixed O&M per kW of rated power. Very low for this chemistry. PNNL's power-equipment overhaul (30 % every 10 years) is not modelled: an estimated few USD/kW-year, stated as a simplification.

Market range No independent range cited.

Reference charging price, shown converted to EUR next to the charging-price input.

Converts the 2021 USD of PNNL to 2021 EUR at the rate of the cost year: currency and year stay matched.

Lower end of the sourced power range. Below 1 MW the size law is not extended and the flag is raised.

Upper end of the sourced power range. Above 10 MW the 10 MW cost is held and the flag is raised.

Reference size of the cost anchor.

Economy-of-scale exponent on total CAPEX with rated power, applied only between the two PNNL sizes (1 to 10 MW). Two points of one source, hence medium evidence. Outside 1-10 MW the specific CAPEX is held at its end value rather than extrapolated.

Market range No independent range cited.

Lower guard of the scaled specific CAPEX; never binds inside the slider domain (checked at every corner).

Upper guard of the scaled specific CAPEX; never binds inside the slider domain (checked at every corner).

Energy of one catalogue product unit, to express the plant size as an equivalent number of Eos Indensity Cores.

Low end of the PNNL 2021 battery LCOS band, in 2021 EUR. PNNL uses a fixed charge rate with US taxes and MACRS; this calculator uses a pre-tax real CRF, which lands lower.

High end of the PNNL 2021 battery LCOS band, in 2021 EUR.

Low end of the PNNL 2030 battery LCOS band, in 2021 EUR.

Lowest PNNL zinc nonflow total installed cost, same all-in boundary as the model.

Highest PNNL zinc nonflow total installed cost, same all-in boundary as the model.

Power of one Indensity Core at 4 h: a single unit is a 0.025 MW system, below the 1 MW PNNL range, so it is costed with the 1 MW figure and flagged.

Maker's expected system life; the reason the economic-life slider goes to 25 years. The model keeps PNNL's 15-year calendar life for the battery modules.

Default real discount rate of the CRF. Real, because every cost is in constant 2021 money with no escalation.

Default horizon of the CRF and of the module-replacement schedule; also the asset life exported to project mode.

Method: PNNL-33283 §6 Eq. 1-3, simplified. LCOS = (CRF x (CAPEX + present value of battery-module replacements) + fixed O&M) / energy discharged + charging price / AC round-trip efficiency. Cycles from PNNL Eq. 2 with the zinc rest times; energy discharged from Eq. 3 with the average usable energy of a linearly fading module. CRF real and pre-tax, not PNNL's fixed charge rate with US taxes and MACRS.

Chemistry: zinc-bromine nonflow, i.e. the Eos Znyth zinc hybrid cathode in PNNL-33283 (source Richey 2021 in the report). Aqueous, non-flammable electrolyte with no circulating electrolyte (PNNL §4.4.1.4); no thermal runaway is modelled or costed. Zinc-air is not covered by these numbers.

Real terms: all costs in constant 2021 EUR (PNNL 2021 USD at the ECB 2021 rate), no escalation, annualised at a real rate. The fixed O&M exported to project mode is an undiscounted yearly cash cost that does not depend on the discount rate.

Sourced domain: PNNL zinc costs exist only at 1 and 10 MW and 4-10 h. Outside it (a single Indensity Core of 25 kW, any plant above 10 MW, any duration above 10 h) no trend is extrapolated: the specific CAPEX stays at its 1 MW or 10 MW value, efficiency and rest time stay at their 10 h value, and the out-of-sourced-domain flag shows 1.

Battery-module replacements: the DC storage block is bought again at each multiple of its life that falls strictly inside the economic life, at the PNNL storage-block cost, discounted at the real rate. They are capital, kept out of the O&M exported to project mode; project mode only replaces the whole asset, so the page shows this share separately (BUG-128).

Customized CAPEX replaces the model value at every size, with no size law. The battery-module replacement cost stays at the PNNL storage-block figure of the selected case.

Convergence: PNNL prints a 2021 LCOS of about 0.20-0.40 USD/kWh for all batteries 1-10 MW up to 10 h, i.e. 169-338 EUR/MWh in 2021 EUR. The model nominal (80 MWh, 8 h) sits below that band because the pre-tax real CRF leaves out PNNL's taxes, MACRS and construction period. The gap is stated, not hidden. The efficiency chain is checked against PNNL Table 4.25 (75 % AC-AC at 4 h), an independent source.

Standalone asset sheet: no revenue, tax, subsidy or degradation of efficiency is modelled; those, and the price spread the plant earns, belong to project mode.