In short. Choosing a fuel or emission route means weighing local air quality, carbon, cost, reliability and compliance over the equipment’s life. A weighted scoring table makes the trade-offs visible and the decision defensible.
Criteria
| Criterion | Consider |
|---|---|
| Regulatory fit | Accepted under current rules |
| Local air quality | NOx and particulate impact |
| Carbon | Lifecycle fuel carbon, not only exhaust |
| Reliability | Fuel supply and engine readiness |
| Cost | Capital, fuel and maintenance |
| Flexibility | Ability to change later |
Options to score
- Existing diesel with RECD.
- Dual fuel.
- Gas set.
- HVO.
- DG plus BESS.
- New compliant diesel.
Scoring method (illustrative)
- Assign weights that total 100 to your criteria.
- Score each option 1 to 5 on each criterion.
- Multiply and sum; examine the top options.
- Test the sensitivity to changing weights.
Score = Σ (weight × option score)
Cautions
Scores are judgement; use data where available. A hospital will weigh reliability heavily; a factory may weigh fuel cost. Lifecycle carbon claims need transparent sources.
Illustrative example
A plant weighting reliability 35, cost 25, regulation 20, air quality 10, carbon 10 finds new compliant diesel scoring highest; changing weights to favour carbon moves gas up. The conversation clarifies priorities.
Lifecycle thinking, simply
A fuel’s carbon footprint includes production, transport and combustion, not only what comes out of the stack. Equipment also carries embodied carbon from manufacturing. A fair comparison looks at these over the equipment’s life, using transparent sources and stated assumptions. Local air quality is a separate issue: a measure that cuts carbon may not cut NOx or particulates, and the reverse.
Separate the three questions
| Question | Indicators |
|---|---|
| Local air quality | NOx, PM, CO, hydrocarbons at the stack |
| Carbon | Lifecycle CO2-equivalent per kWh |
| Cost and reliability | Lifetime cost, availability, resilience |
Worked scoring example (illustrative)
| Criterion | Weight | Retrofit diesel | Dual fuel | New compliant diesel |
|---|---|---|---|---|
| Regulation | 25 | 3 | 3 | 5 |
| Reliability | 30 | 3 | 3 | 5 |
| Cost | 20 | 4 | 3 | 2 |
| Air quality | 15 | 3 | 4 | 5 |
| Carbon | 10 | 2 | 3 | 2 |
Multiply each score by its weight and add. Then change the weights and see whether the ranking holds. If it flips easily, the decision depends on values, not data, and the organisation should discuss priorities explicitly.
Handling uncertainty
- Fuel prices and availability change.
- Rules change.
- Technology improves.
Prefer options that keep flexibility, such as equipment that can accept more than one fuel, or modular systems.
Reporting
If you report emissions, state the method, boundaries and sources, and avoid claims that cannot be supported by data.
The master engineering question
What do we value most, and does the chosen route still look right if that priority shifts?
What to send us
Send site priorities. Send your application details.
Questions engineers ask
Is lifecycle carbon needed?
If carbon is a goal, yes.
Is scoring objective?
Partly; document assumptions.
How often to revisit?
When rules, fuels or loads change.
Can I mix routes?
Yes, per set.
General guidance only. Values illustrative.