What Would Stage 5 Emissions Regulations Mean for the UK Post-Brexit?


If Brexit were to happen tomorrow, the EU’s tier 5 diesel generator emissions standards would stand until and unless the UK government chose to replace them – but if they did, what would they be replaced with?


One opinion held that the UK would wait until the US promulgates their version of the stage 5 regulations, most likely to be called ‘tier 5’ in their nomenclature. The UK would naturally want to keep its close ties with the American markets, additionally, the American regulations would be expected to remain virtually identical to the existing EU stage 5 emissions standards for diesel generating equipment.

So really, not very much would change.

There are a few good reasons for that. First and foremost, the US regulations will almost certainly fall in line with the EU ones. Many big diesel engine manufacturers are multinational companies who already sell to both US and EU markets. It is far too expensive to have different production lines set up to meet different market regulations, so they are essentially already gearing up to produce EU stage 5 emissions-ready stage 5 gen sets. For the same reason, the UK government has every reason to continue putting out emissions standards that mirror both the US and EUregulations, for sheer efficiency.

There has been an almost exact parallel between EU and US emissions standards in this regard for the better part of a decade. There has long been an assumption that the EPA would essentially clone the stage 5 emissions standards, just as they have done before with stage 3 / tier 3, stage 4 / tier 4 and stage 3b / tier 4 interim. However, the current administration shows no sign of movement on this front. The EPA hasn’t said much about its plans, though California, a big enough market to make international changes on its own, has hinted that they could implement tier 5 type regulations on a state level.

Another important point is that the EU’s stage 5 emissions standards are not all that difficult to meet, nor are they likely to change dramatically. Most of the industry leading manufacturers say that a hypothetical US tier 5 would be almost identical to their existing tier 4 final in any case.

Like the EU’s stage 5, any UK tier 5 regulations will likely apply to all mobile diesel generators.

Stage 5 regulations of course apply to excavators, wheeled loaders and tractors, but they also apply to mobile gen-sets – both those built on mobile trailers and those commonly transported to work locations by truck, such as those offered by equipment rental and ‘plant hire’ companies. The only non tier 5 gen-sets would be those which are permanently fixed in a single location.

Is there anything that might be different under a US-style Stage 5?

Unlikely, but possibly. Stage 5 applies to all appropriate engines, regardless of horsepower, so a hypothetical UK stage 5 is likely to do so as well. This is a shift from stage 4, where engines of less than 24 horsepower were exempted. This won’t matter for most industrial or commercial stage 5 gen-set users, but may be more important for home and camping users.

Many in the US are pushing for regulations with substantially lower NOx limits for smaller engines as well. It is not guaranteed that this will be an exact parallel with the EU’s stage 5 standards, and there will probably be quite a bit of wrangling (and lobbying) before those numbers would be set. If a difference between a new UK stage 5 and the existing EU stage 5 were to develop, it might well be her

Would US-Style Stage 5 diesel generators require new technology?

Almost certainly not. Stage 5 certainly didn’t call for anything radical. Industry experts are certain that off-the-shelf solutions for whatever standards are eventually decided on are already available. Any US version would be expected to require the same standards.

There are likely to be different technologies developed to meet stage 5 emissions regulations more efficiently for different sizes, types and applications of diesel engines. However, there is no one ‘magic bullet’ technology which would be likely to change the designs of all engines, save perhaps the diesel particulate matter filter (DPF).

The core changes would almost certainly require less particulate emissions, especially sub-micron level soot. The current medical understanding is that these can become easily lodged in the lungs, and do cause long term problems.

However, the technology to catch these – particulate matter filters – already exist and already work quite well. These have been required for certain engine types ever since stage 3, for larger particulates. Simply making diesel particulate filters more effective at catching microscopic particles as well does not require any novel technologies.

Particulate matter filters are already much more advanced that stage 3 or stage 4 regulations require. The older type of filters needed to be periodically ‘regenerated’, so that accumulated soot could be burned away from the inside of the filter. Even so, they eventually clogged with ash, and needed to be replaced or cleaned.

In response, both the engines and the filters were redesigned. Smaller engines were re-engineered so that they met the PM emissions standards without any filters at all. This wasn’t practical for engines of much more than 75 horsepower, so most of these are already fitted with modern, more efficient DPF filters. Simply swapping them out at the manufacturing stage with stage 5 emissions compliant filter types will be easy.

The only real change necessary to comply with stage 5 (and therefore likely for a US tier 5 type regime as well) is in the manufacture of 19 kW to 37 kW diesel gen-sets. Many of these had not needed exhaust aftertreatment or common rail fuel systems in the past. Even then, the changes are already being made to almost all production lines in order to sell their products in Europe, so applying a similar requirement to mobile diesel generators destined for sale in the UK should not impose too great a burden.

Most experts say that all engines, small and large, will soon have stage 5 compliant DPFs fitted in any case. Making them tier 5 compliant as well may not even require any changes. However, the current stage 5 and likely tier 5 emissions standards are likely to drive additional advances in DPF filters.

In the end, adapting to stage 5 took very little radical change on the part of manufacturers. The same will likely be true for tier 5 when it is imposed.


If a UK stage 5 follows a US tier 5, what kind of transition period can we expect?

The EU’s ‘stage 5’ (the equivalent of out Tier 5 emissions regulations) are due to be phased in in 2019/2020, and by and large the industry is comfortable with them and the time frame. They will be producing EU Stage 5 compliant equipment in 2019 and 2020 already, and any heightened requirements that a UK stage 5 emissions regulations would add would expected to be minor. They would almost certainly have a delay period similar to the EU regulations as well, and wouldn’t likely apply until well after 2020.

Under the EU’s stage 5 scheme, large original equipment manufacturers had 18 months to ‘use up’ the last of their stocks of non-compliant engines and equipment, as well as a further 6 months to get them onto the market. Smaller manufacturers – those who produced less than 100 units each year – were allowed an additional year to sell the last of their non-compliant units.

If a UK stage 5 emissions standard follows the same pattern of transition as the EU’s stage 5, many manufacturers could be selling non-compliant tier 5 gen-sets until at least 2021. That is assuming some kind of UK stage 5 regulations are adopted before the end of the year, something which seems extremely unlikely.


Is Diesel Generator Direct UK ready to deliver stage 5 compliant mobile diesel generators?

Most definitely. We have gathered a great deal of expertise gearing up our products for the EU’s stage 5 regulations, and the imposition of similar US tier 5 emissions standards here in the UK will not slow us down in the least. Our newest stage 5 diesel generators will make use of SCR (selective catalytic conversion) systems, DOCs (diesel oxidation catalysts) and DPFs as appropriate to engine type, size and use, and will meet all required standards based on their manufacturing date.

We are implementing continuous low-temperature DPF regeneration technology already, so that DPF regeneration never interrupts the duty cycle of our gen-sets. This is simply the best, most effective and most convenient engineering solution. It would be the right choice for the UK markets, even if (as is likely) UK-specific stage 5 emissions standards are never promulgated.

In short, we are ready to supply the right mobile and static diesel generating equipment to our clients in the UK, and anywhere else in the world.

No one is expecting a US tier 5-style implementation that would surprise or inconvenience the industry, but even if it did, we stand ready to adapt to the challenge.