Clean Backup Power Technology Requirements, Base Specification Version 0.3 (effective Apr 22, 2026)

Overview

The specification is performance-based and technology-agnostic. Candidate solutions include PEM fuel cells, clean-fuelled generators (renewable natural gas, e-fuels, hydrogen, green methanol) and long-duration energy storage, and the document gives them one common set of criteria for judging whether they can serve as mission-critical backup. The aim is to give suppliers a clear target and to align the industry, colocation providers included, on the same requirements.

'Clean' has two tiers. Zero-carbon means no Scope 1 emissions of CO2, NOx, SOx or PM at the point of use in steady-state operation. Low-carbon transition means considerably lower Scope 1 emissions than a Tier 2 diesel generator without after-treatment. The comparison baseline is a diesel engine emitting 1742 lb/MWh of CO2. Emissions rank from highest to lowest as diesel, diesel with SCR, natural gas, natural gas with SCR, hydrogen engines, and PEM fuel cells, which approach zero. The text names reducing the baseline to under ten percent as the ideal target.

Technical requirements sit in four tables. The system must be a self-contained grid-forming source that can isolate from the utility, deliver power within 10 s of the signal and transfer to island mode in under 8 ms. The target scale is 40-50 MW sites growing to 300 MW-1 GW, with a preferred module size of 2-10 MW. Typical availability is 99.99% for the backup system and 99.999% at site level through N+m. The testing section covers factory acceptance, a sub-scale efficiency validation and site acceptance tests.

Energy storage such as BESS is deliberately placed in a separate category. Generation units can run indefinitely if refuelled, whereas storage may only be used where the grid operator guarantees that an outage will never exceed its duration. Several values remain as placeholders in square brackets ([X] MW continuous output, [X] kg CO2e per kW embodied-carbon cap), and the version history shows only an initial version, so the document is clearly a draft.

Key points

1. The emissions baseline is a diesel engine at 1742 lb CO2/MWh; ranking runs diesel, diesel+SCR, natural gas, natural gas+SCR, hydrogen engines, PEM fuel cells (near zero).
2. Self-contained grid-forming source; start-up within 10 s of signal; island transfer under 8 ms (quarter cycle); 100% block load acceptance.
3. Overload 110% for 60 s and 150% for 3 s; transient voltage response to ISO 8528-5 G3; steady-state frequency within +/-0.5%.
4. THD at most 5% at full load (IEEE 519); IEEE 2800 ride-through and IEEE 1547-2018 certification; output 480 VAC 3-phase 60 Hz (performance guaranteed at 13.8 kV) or 0-800 VDC.
5. Scale 40-50 MW rising to 300 MW-1 GW; module 2-10 MW; TRL 8 or above; backup availability 99.99% and 99.999% site level with N+m; concurrent maintainability.
6. Indefinite runtime with integral fuel storage sized for refuelling time; containerised or skid, typically 2.5 x 6.0 m and under 12,000 kg; -20 to +50 C; NFPA 110 Level 1; explosion-proof enclosures for hydrogen or e-gas.
7. Zero-carbon goal is 0.0 g/kWh direct CO2e and zero criteria pollutants; low-carbon transition must meet EPA Tier IV; hydrogen engines NOx under 0.02 g/bhp-hr with SCR; third-party verified Type III EPD per ISO 14025.
8. Noise limited to 75 dBA at 1 m from the enclosure; chemical storage must recover over 95% of critical minerals (lithium, cobalt, nickel); lead, cadmium, mercury and hexavalent chromium are prohibited.
9. System life of at least 15 years with midlife refurbishment and spare parts for at least 10 years after end of life; interface must natively support DNP3 or IEC 61850 and OpenADR 2.0b.

Using it in design

• Extend the generator catalogue with technology type (diesel, HVO, gas, H2 ICE, PEM fuel cell), emissions factor relative to the 1742 lb/MWh baseline, start time, block-load capability and NFPA 110 level.
• In the backup-power check, verify start-up within 10 s and 100% block load; where a source cannot meet them, require a UPS or battery bridge sized for the gap.
• For hydrogen or e-gas options, add rules for explosion-proof enclosures, hazardous-area classification and on-site fuel storage sized to the refuelling time.
• Restrict storage-only backup to cases where the grid operator guarantees a maximum outage duration; otherwise flag that a generation unit is needed.
• Report Scope 1 backup emissions and equipment embodied carbon (Scope 3, from the EPD) in the sustainability summary.
• Carry the module footprint (2.5 x 6.0 m, under 12,000 kg) and the 75 dBA at 1 m limit into layout and noise checks.

Who should read it

Electrical designers, sustainability engineers and equipment suppliers weighing backup-power architecture, generator alternatives and carbon targets together.

Document contents

1. License
2. Compliance with OCP Tenets
3. Overview
4. Introduction to clean backup technologies
5. Technology Agnosticism and Focus
6. Definition of Clean
7. Technology Evaluation Methodology and Baseline
8. Emissions Reduction Methodology and Technology Eligibility
9. Definitions
10. Referenced Codes and Standards
11. Detailed Specifications
12. Technical Viability and Reliability
13. Scope, Scale, Reliability and Operating Environment
14. Sustainability and Emissions Requirements
15. Testing, Management, and Lifecycle
16. Site Acceptance Testing (SAT)
17. Compliance

Related standards

• ISO 8528-5
• NFPA 110
• NFPA 2
• IEEE 1547-2018
• IEEE 2800
• IEEE 519
• UL 2200
• UL 9540
• IEC 62282-2

Read the document

Publication details

Authors

Open Compute Project Foundation

Publisher

Open Compute Project Foundation

Year

2026

Document number

v0.3

Document language

English

Source type

Industry body

Access

Open licence — downloadable

Licence

OWFa 0.9 — Open Compute open specification licence; redistribution permitted

Licence evidence

www.opencompute.org

Citation