If you’re running, or considering, one of our larger Talbott MWE biomass boilers, there’s an additional layer of regulation worth understanding on top of the standard Part B environmental permit: the Medium Combustion Plant Directive, or MCPD. This article explains what MCPD actually requires, which Talbott installations it applies to, and how the MWE range — combined with Air Plants’ ceramic filtration technology — is engineered to meet it comfortably.
If you haven’t already, it’s worth reading our companion guide, “Environmental Permits for Waste Wood Boilers: A Guide to Part B Permits”, first — MCPD sits on top of that Part B framework rather than replacing it, and this article assumes that base level of understanding.
What is the Medium Combustion Plant Directive?
MCPD (EU Directive 2015/2193, retained in UK environmental permitting regulation) applies to combustion plants with a rated thermal input of 1MW or more, up to 50MW. For waste wood combustion specifically, this sits within the existing Part B permitting framework — but plants of 1MW or more move from local authority regulation to the Environment Agency (in England) or Natural Resources Wales, and face additional monitoring, record-keeping and emission limit requirements.
Practically, this means two things change once you cross the 1MW thermal input threshold: who regulates your permit, and how tightly your emissions and operation are monitored.
Which Talbott products does this apply to?
Most Talbott MWE installations sit comfortably below the MCPD threshold. It typically becomes relevant for:
- The MWE999 and MWE1500 — our largest two MWE models. Using a typical efficiency assumption of around 85%, an MWE999 (999kW heat output) corresponds to a rated thermal input in the region of 1.2MW, and an MWE1500 (1500kW heat output) to approximately 1.8MW — both within MCPD scope. Your plant’s exact rated thermal input will be confirmed as part of your permit application, based on your specific appliance and fuel.
- Multiple smaller units on a shared system. Even if no single boiler individually exceeds 1MW, regulators may assess multiple appliances as a single plant for permitting purposes if they could reasonably be replaced by one larger unit, share the same fuel storage, feed into a common heating system, or serve the same business activity. If your site has several Talbott units that collectively exceed 1MW combined thermal input and meet these criteria, MCPD may still apply. This is assessed case by case by your regulator, so it’s worth raising directly with them at the design stage rather than assuming either way.
Key compliance deadlines
- New plants — any plant put into operation from 20 December 2018 onwards must comply with MCPD requirements from day one. If you’re specifying a new MWE999 or MWE1500 installation now, this applies to you immediately.
- Existing plants over 5MW thermal input — already required to comply, since 1 January 2025.
- Existing plants between 1MW and 5MW thermal input — must comply by 1 January 2030. This covers most existing MWE999 and MWE1500 installations, and while 2030 may feel some way off, bringing an older installation up to current emission control standards is not something to leave until the last minute.
What MCPD requires
On top of standard Part B requirements, MCPD-scope plants face:
- Tighter emission limit values, particularly for dust, which tighten further from 2030 for existing plants
- Detailed record-keeping, including the type and quantity of fuel used, evidence of continuous effective operation of any secondary abatement equipment, and records of any malfunction or breakdown of that abatement equipment
- Annual emissions testing as standard, using accredited (MCERTs) methods
- Regulation by the Environment Agency or Natural Resources Wales rather than your local authority, generally involving a more detailed permitting process
How Talbott MWE and Air Plants technology helps you meet this
This is exactly the territory the MWE range was engineered for. A few features work together to keep MCPD-scope installations comfortably compliant, rather than close to the limit:
- Lambda sensor control continuously monitors oxygen levels in the combustion chamber and adjusts air supply in real time — precisely the kind of good combustion control that keeps carbon monoxide low and thermal efficiency high, rather than swinging between too little air (incomplete combustion, high CO) and too much (heat loss, higher dust carryover).
- Automatic, continuous fuel feed avoids the stop-start burning that produces the biggest spikes in emissions, keeping combustion stable across variable load.
- Automatic de-ashing and automatic heat exchanger cleaning maintain consistent combustion chamber conditions and heat transfer efficiency over time, rather than performance drifting between manual cleaning cycles.
- Electrical heat ignition brings the combustion chamber up to temperature cleanly before fuel is introduced, with a virgin wood pre-start also available as an option.
- Air Plants ceramic filter systems, purpose-built for hot flue gas filtration, are capable of dust emissions below 10 mg/Nm³ — comfortably under even the tightest emission limits that apply to existing plants from 2030, with headroom to spare.
Together, this means an MWE installation isn’t just designed to scrape past MCPD limits on the day it’s commissioned — it’s built to keep performing well within them for the long term, which matters given these are typically decades-long assets.
What this means practically for you
If you’re operating or specifying an MWE999 or MWE1500, or a multi-unit Talbott installation that may collectively exceed 1MW thermal input:
- Confirm your plant’s actual rated thermal input as part of your permit application — this is based on your specific fuel and appliance, not a generic assumption.
- Engage the Environment Agency or Natural Resources Wales early if you’re within MCPD scope, rather than assuming local authority processes will apply.
- Keep the enhanced records MCPD requires from day one — fuel type and quantity, and abatement equipment performance — not just the standard Part B record-keeping.
- If you have an older installation approaching the 2030 deadline, start the conversation about upgrades now rather than waiting — bringing an existing plant up to current standards can take time to plan and budget for properly.
Talk to us
Whether you’re specifying a new MWE999 or MWE1500 installation, or want to understand where an existing multi-unit system stands with MCPD, get in touch with our team — we work through exactly this with customers regularly, and can talk through what it means for your specific site.
Important note
This article is intended as general educational information based on current guidance (technical guidance PG5/1(21), successor to PG1/12(13)), which was in pre-publication draft status at the time of writing but is already being applied in practice by regulators. Whether MCPD applies to a specific installation — particularly for multi-unit sites — depends on site-specific factors assessed by your regulator. Always confirm your own requirements directly with the Environment Agency, Natural Resources Wales, or a qualified environmental consultant before making compliance decisions.