SOFC vs Gas Genset for UK Data Centre Power: What the Numbers Actually Show
Solid oxide fuel cells (SOFCs) beat gas-fired gensets on electrical efficiency, around 60% against 40%, which cut 20-year opex in our model of a 100 MW UK data centre with a 50 MW grid connection. But SOFC capex is in a different league, and slow ramp rates mean they’re not a straight swap for flexible generation.
Key points
- Bloom Energy and Oracle expanded their partnership on 13 April 2026 to deploy up to 2.8 GW of fuel cell capacity (Bloom Energy).
- Maximum electrical efficiency is around 60% for an SOFC against 40% for a gas-fired genset (Table 1; the US Department of Energy also lists 60% for SOFCs).
- In our Gridcog model, 20-year opex for a 100 MW data centre was £1,135 million with an SOFC against £1,412 million with a gas genset, a difference of £277 million (Figure 1).
- Capex in our comparison is £5,000/kW for an SOFC against £1,000/kW for a gas-fired genset (Table 1).
- SOFCs ramp at about 1% per minute, so they run like a baseload asset rather than following prices and solar output as a genset does (Figure 2).
Why are data centres looking at solid oxide fuel cells?
There’s been a lot of noise around solid oxide fuel cells (SOFCs) for data centres, most recently the headline-grabbing deal between Bloom Energy and Oracle, announced on 13 April 2026, for nearly 3 GW of behind-the-meter generation. It’s a striking number, and it got us curious enough to run a simulation in Gridcog to see how SOFCs actually stack up against a more conventional alternative: gas-fired gensets, providing firm behind-the-meter supply.
How did we model an SOFC against a gas genset?
We modelled a 100 MW data centre with a 50 MW grid connection to SSEN’s Southern Electric Power Distribution (SEPD) network in the UK. The balance of energy comes from behind-the-meter generation, either a genset or SOFC, alongside co-located solar and battery storage. Supply costs include the day-ahead market for the energy commodity, network charges, and gas fuel costs, all modelled at 30-minute resolution.
| Attribute | Gas-fired genset | Solid oxide fuel cell |
|---|---|---|
| Energy production | Combustion | Electrochemical |
| Fuel | Gas | Gas |
| Max electrical efficiency (%) | 40 | 60 |
| Ramp rate / responsiveness | Fast: up to 100% per minute | Slow: about 1% per minute |
| Plant configuration | More centralised (units of several MW) | Highly modular (units down to 100s of kW) |
| Emissions (kg CO2-e per kWh) | 0.5 | 0.37 |
| Capex (£/kW) | 1,000 | 5,000 |
Table 1: High-level technology comparison between a gas-fired genset and a solid oxide fuel cell
Model assumptions, from the notes to Figure 1:
- Grid connection: 50 MW at extra high voltage
- Energy commodity priced at day-ahead, using the last 12 months of pricing
- Gas supply cost: 5p/kWh
- Efficiency: 40% for the genset, 60% for the SOFC
- Ramp rate: 20% per minute for the genset, 1% per minute for the SOFC
Is an SOFC cheaper to run than a gas genset?
Electrical efficiency is where the SOFC makes its clearest case. The jump from roughly 40% efficiency (gensets with natural gas) to around 60% (SOFCs) translates directly into higher utilisation. The SOFC runs more hours, more consistently, and regularly displaces grid-supplied energy. Over a 20-year horizon, those opex and emissions savings are meaningful.
Figure 1: 20-year opex for a 100 MW data centre, gas-powered genset vs SOFC, each with co-located solar and storage. Genset: £1,412 million. SOFC: £1,135 million. Costs are split into wholesale energy, network and fuel. Note: 50 MW connection at extra high voltage; day-ahead prices from the last 12 months; gas at 5p/kWh; genset efficiency 40% and SOFC 60%; genset ramp rate 20% per minute and SOFC 1% per minute.
| Scenario | 20-year opex (£ million) |
|---|---|
| 100 MW data centre with gas-powered genset, solar and storage | 1,412 |
| 100 MW data centre with SOFC, solar and storage | 1,135 |
| Difference | 277 |
Table 2: Modelled in Gridcog – 20-year opex by scenario (from Figure 1)
But that efficiency premium comes at a cost. Capex for SOFCs is in a completely different league to conventional gensets, and that upfront burden is a serious consideration for any project finance model.
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How do SOFCs and gas gensets dispatch differently?
Fuel-powered generators are fast and flexible. In a system with variable solar output, time-of-use pricing, and co-located storage, they respond: ramping up when prices spike, backing off when solar is strong, working together with the battery.
SOFCs operate more like a baseload asset: their slower ramp rates mean they are less able to respond to price signals and external conditions. They run steadily, which is fine and often desirable, but they don’t flex the way a genset does. When optimising across a portfolio of assets with dynamic inputs, that distinction matters and shows up clearly in the dispatch modelling.
Figure 2: Energy supply mix for a 100 MW data centre, gas-powered genset vs SOFC with co-located solar and storage. Example dispatch and annual generation mix on 21 March, 1 May and 15 October 2027, in response to different market conditions and solar performance, at 30-minute resolution.
Should a data centre choose an SOFC or a gas genset?
SOFCs make a compelling long-run efficiency argument, but the capex hurdle is real, and the operational characteristics mean they’re not a straight swap for flexible generation. The right answer depends on the specific system configuration, and that’s exactly the kind of question Gridcog is built to help answer.
| Option | Suits | Watch out for |
|---|---|---|
| Solid oxide fuel cell | Long-run efficiency; steady, baseload supply; lower 20-year opex and emissions | Capex in a different league; slow ramp rates, so less response to prices and solar |
| Gas-fired genset | Flexible supply that ramps with prices, solar output and the battery | Lower efficiency, so higher fuel spend and emissions over 20 years |
Table 3: Which suits which, based on the modelling above
Read more in our data centre deep dive, Optimising energy for UK data centres: grid, hybrid, and microgrid approaches.
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Frequently asked questions
What is a solid oxide fuel cell (SOFC)?
A solid oxide fuel cell (SOFC) generates electricity electrochemically rather than by combustion. In our comparison it runs on gas, like a genset, but reaches a maximum electrical efficiency of around 60%. The US Department of Energy lists SOFC operating temperatures of 500–1,000 °C and names long start-up times and a limited number of shutdowns as challenges.
How efficient is an SOFC compared with a gas genset?
Around 20 percentage points more efficient. Our comparison assumes a maximum electrical efficiency of 60% for an SOFC against 40% for a gas-fired genset. In our model of a 100 MW data centre, the higher efficiency meant the SOFC ran more hours, more consistently, and regularly displaced grid-supplied energy.
How much does an SOFC cost compared with a gas genset?
About five times as much per kilowatt in our comparison, though firm price data is hard to find: £5,000/kW for an SOFC against £1,000/kW for a gas-fired genset. That upfront cost is a serious consideration for any project finance model, even though the SOFC cut 20-year opex from £1,412 million to £1,135 million in our 100 MW data centre model.
Can an SOFC follow electricity prices like a genset?
Not well. SOFCs ramp slowly, at about 1% per minute in our comparison, against up to 100% per minute for a gas-fired genset. They run like a baseload asset, so they respond less to price spikes, solar output and battery dispatch, while a genset ramps up when prices spike and backs off when solar is strong.
Do SOFCs produce lower emissions than gas gensets?
Yes, per unit of electricity. Our comparison uses 0.37 kg CO2-e per kWh for an SOFC against 0.5 kg CO2-e per kWh for a gas-fired genset, because the SOFC converts gas to electricity more efficiently. Both still run on gas, so neither is zero-carbon on its own.
What is the Bloom Energy and Oracle fuel cell deal?
On 13 April 2026, Bloom Energy and Oracle expanded their partnership under a master agreement for up to 2.8 GW of fuel cell capacity to power AI infrastructure, with an initial 1.2 GW contracted and deploying. Bloom says it delivered a fully operational fuel cell system to Oracle in 55 days.
Can Gridcog model fuel cells and gensets for a data centre?
Yes. In Gridcog you can add generators to a project regardless of fuel type and reflect their operating parameters, including ramp rates, heat rate curves and must-run periods. You can then model them with a constrained grid connection, solar and battery storage at 30-minute resolution to compare opex, emissions and dispatch.
Sources
- Bloom Energy, Bloom Energy and Oracle expand strategic partnership to deploy up to 2.8 GW to accelerate AI infrastructure build-out, 13 April 2026
- Reuters, Bloom Energy to supply up to 2.8 GW of fuel cells under expanded Oracle deal, 13 April 2026
- US Department of Energy, Comparison of fuel cell technologies, last modified 2 June 2026
- Gridcog modelling: 100 MW data centre with a 50 MW grid connection, genset or SOFC with co-located solar and storage (Figures 1 and 2)
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