Emissions — the RFNBO screen per product

In simple terms

The Emissions tab (under Tools, in both stages) answers one question per product: how much carbon does a megajoule of it carry, and is that under the RFNBO limit? The EU rule for renewable fuels of non-biological origin asks for at least a 70 % saving against a fossil fuel at 94 g CO₂e/MJ, so at most 28.2 g CO₂e/MJ.

It is a screen, not certification. The only emission source the model tracks is grid electricity, so the screen counts that against the energy in each product. Passing it shows a design is not already ruled out on that one measure; it does not make a product certified.

What the tab shows

Part	What it says
Compliance target	RFNBO is the one target computed. IMO (shipping fuels) and the EU Taxonomy are listed and say they are not computed.
Carbon intensity per product	A bar per product against the 28.2 limit line, the 94 comparator marked, the marginal band shaded (drawn once some grid energy gives a product an intensity above zero); a verdict sentence computed from the figures; a table with the intensity, the saving against the comparator, the headroom and the verdict. Hover or keyboard focus reads one product out.
Grid budget per product	The grid energy and CO₂ charged to each product, the most grid energy it can take and still pass, and the room left (or by how much it is over).
Grid emissions by source	The grid’s fossil and balancing part at the grid’s carbon intensity, the renewable-PPA part at zero, and the total.
Renewable share of the hydrogen	The share of the electrolyser’s electricity that came from wind, solar or the renewable PPA.
Not modelled	What the screen leaves out, said plainly (below).

The verdict

Verdict	When
✓ passes	the intensity is under the limit by at least 10 % of it (25.4 g CO₂e/MJ or less)
△ marginal	it passes, but within 10 % of the limit (above 25.4 g CO₂e/MJ): a dirtier grid year could put it over
✕ over the limit	the intensity is above 28.2 g CO₂e/MJ
– does not apply	green iron and green steel are not fuels, so the fuel rule does not apply; their share of the grid’s emissions is still counted
○ nothing made	the product made nothing in this result, so there is nothing to screen
? not screened	its share of the plant’s grid emissions could not be worked out; it is named, never passed

The tiers are the Configuration Finder’s own, so a design reads the same in both places. The sentence above the chart is computed from the figures; when a product is over, it names the grid energy the plant would have to come down to.

Where the figures come from

Prefeasibility — the stage’s own design, solved when you open the tab and stored nowhere. The annual mode has no grid, so every fuel scores 0. In the timeseries mode the only grid energy is the backstop for the auxiliaries (turn it on in the cockpit’s resolution settings). There is no renewable PPA at this stage, and the electrolyser never takes grid power, so the hydrogen is 100 % renewable.
Feasibility — the stored solve, never a new one. Without a stored solve the tab says so and offers the solve. The total is the figure the solve stored, the carbon intensity and PPA share are the ones it used, and the line under the basis says when the design or the assumptions changed since.

How the plant’s grid emissions are shared between products: by the hydrogen each product used (its tonnes times the hydrogen a tonne of it needs) — the split the grid bill and the shared plant’s cost already use. So the products add back to the plant, and a product made in small quantities is not charged with the whole plant’s grid draw. The Grid tab’s RFNBO card shows the same screen for the largest product, and the Design lab’s finder and grid-cap scan charge a product the same share through the same function (since 2026-11-09) — so every place shows one number per product.

The grid budget holds today’s output and split fixed: it is the most grid energy a product can be charged and stay under the limit, at the grid’s carbon intensity less the renewable PPA share.

Not modelled

Additionality — whether the renewable power comes from new plants built for this project. A pass-or-fail test, not a number.
Hour-by-hour matching — whether each hour’s electricity is matched by renewable power produced in the same hour and the same area. A pass-or-fail test.
Making the equipment — the emissions of building the turbines, panels, electrolysers and plant.
Transport and distribution of the product to its buyer.
Other supply-chain emissions (scope 3) — inputs bought in, such as CO₂, ore or chemicals.
Fuel burnt for process heat — process heat is recorded, not supplied; a fired boiler would add emissions this screen does not count.

In the documents

The Results workbook has an Emissions sheet and the summary report (PDF, Word, PowerPoint, HTML) an Emissions — the RFNBO screen per product section, with the same figures, for the stage you export from. See Documents.

Feasibility suite — the Grid tab and its RFNBO card
Documents — what each file contains
What the model leaves out