In 2021, CAGE Technologies (Clean Air Gas Engine) began developing its own low-carbon engine, explains CEO Paul Andrews. But it then saw a more important opportunity to turn its technology to making engines that use a wide range of waste fuels.

As a result, it now produces innovative world-leading engine systems for industrial and agricultural machines that run on sustainable and zero emission fuels.

Supported by early financial advice from RedCAT, CAGE engines can burn biogases with methane and a high carbon dioxide content from covered farm slurry lagoons to generate off-grid electricity. They can also use waste gas to produce valuable power from millions of used aerosol cans, and from the pyrolysis of plastic waste which is a source of both valuable oil products and carbon black.

Additional advantages are that the CAGE control system will tolerate fluctuating methane/CO2 concentrations – and gases made from different combustible components – while operating with no compromises when compared to conventional diesel engines.

The key point, as Paul Andrews explains, is that “… better combustion makes better engines.” Using this approach, his vision is to improve air quality in developed countries while combining the collective power tens of millions of small farms in India, Africa and Latin America to make a global difference.

Part of CAGE’s practical answer here is a partnership with a major Lancashire based importer which supplies large numbers of small diesel generators to the UK and EU through global manufacturing and supply agreements. This partnership can enable the production of bespoke biogas generators that CAGE can in turn supply to biogas partners in the Global South at prices appropriate to these emerging markets.

COP30 in Brazil in November 2025 was divided on the issue of phasing out fossil fuels to reach net-zero emissions. Its approach was very much one of tackling the obvious low hanging fruit, says Paul. But there are overlooked alternatives that could be scaled-up massively around the globe, he believes.

By law, UK farms must now cover slurry lagoons (liquid animal manure) so the methane and carbon dioxide produced by decomposition does not escape to atmosphere. CAGE is able to use this gas with no expensive treatment processes needed, to remove the 50% inert CO₂ content. The result is that it can produce electricity from optimised biogas generators at very low cost.

It similarly collects decomposition biogases gases from anaerobic digester plants at wastewater (sewage) treatment works, industrial, and agricultural schemes, plus residual landfill gas.

The big saving is in replacing conventional sources of energy with these otherwise wasted resources to cut overall carbon footprints.

All aerosol cans contain a pressurised gas. When cans are exhausted, they still retain this combustible propellant at atmospheric pressure. By law, this must be removed and destroyed.

By adding an extra process, CAGE partners harvest and store this gas which is then used to power the recycling plant with electricity from a CAGE generator – saving recyclers thousands of pounds in disposal costs. Two of the UK’s largest recyclers are now clients.

One way of processing certain types of plastic bottles is pyrolysis – thermal decomposition at high temperatures in an oxygen-free environment. This produces combustible gases that can be used as engine fuel, liquids (bio-oil/tars), and solids such as valuable carbon black used in tyre manufacture. This turns waste plastic from a landfill nightmare into a valuable waste commodity.

A key CAGE focus is off-grid plastic disposal as a high-value energy source.

Meanwhile, the UK construction sector is at a pivot point where CAGE solutions can help.

The industry knows it must reduce diesel use to help reach net-zero and ensure cleaner air. As a result of new data, regulatory pressure, and key project precedents, it is moving towards low-carbon and hybrid clean energy systems that have a high commercial value. CAGE is at the forefront here.

Construction’s 2024 direct Scope 1 emissions were more than 11 million tonnes of CO₂e – 30% higher than 2014 primarily because the sector relies on thousands of costly-to-run diesel-powered on-site units.

Red diesel subsidies ended in 2022. Contractors now pay the full-price of fuel. Meanwhile, fossil fuel prices are volatile. After an 11% year-on-year fall, diesel remained above its 10-year price average.

In parallel, new Scope 1, 2 and 3 emissions reporting requirements strengthened for 2025 mean that firms must cut their fuel-related footprints or face criticism from clients, regulators, investors and the public.

The target of the Construction Leadership Council’s Zero Diesel Sites Route Map is to remove 78% of diesel plants by 2035. CAGE expects to make a major contribution here.

As part of initial feasibility reporting, RedCAT analysed CAGE’s innovation potential. It also carried out business due diligence which then moved forward into support for a work package focused on core component optimisation/simulation and development process improvement.

That was followed by support for a strategic scale-up of commercialisation, plus business processes, operational productivity & supply chains, strategic marketing and PoC (Proof of Concept) Beta sites.

Further help was given for future fundraising/investment strategies. These covered commercialisation analysis and fundraising preparations.

A second strategic marketing theme developed a range of sector marketing messages that fed into a national and international RedCAT Advocacy campaign.

RedCAT also initiated a skills and operational scale-up review as part of future growth planning.

A deeper overview of CAGE’s innovations may be helpful.

The company’s engines are designed to provide robust, reliable, scalable plug-and-play technology solutions in the 2-60kW range using gas with a 45% or higher methane level, explains Paul.

The result is performances similar to equivalent-size diesel engines. When used on micro-scale agricultural anaerobic digestion plants, CAGE gensets produce power while the AD process creates organic fertiliser.

These systems are designed to optimise power-on-demand with significant CO₂ emission cuts. CAGE has demonstrated the benefits of this combination of technologies with hybrid welfare cabins for Mace-Dragados and Costain-Skanska on HS2 sites.

CAGE’s net-zero capability with green hydrogen as a fuel is also being proved in a hydrogen-solar-battery hybrid welfare unit trial at Kirkwall cruise terminal on Orkney with the European Marine Energy Centre (EMEC).

CAGE combustion control systems on hydrogen engines eliminate NOx emissions, zero particulates, and achieve high levels of thermal conversion efficiency. Engines are available in the sub-30 kW range; larger output units are being developed.

The company has also been developing a hybrid gas engine for switching from red diesel to hydrogen, biomethane or bioLPG simply by changing settings on the generator, and a phased move to 100% hydrogen as the UK hydrogen sector develops.

CAGE ultra-low emission LPG engines and generators are direct replacements for diesel in the 2-57kW range. They reduce CO₂ emissions and surpass the EU Stage V exhaust emission standard.

The company has also developed low-cost technologies for standard petrol and diesel engines to run on low carbon fuels – LPG, biogas and hydrogen – with optimised efficiency. These can be fitted to construction equipment. CAGE is working with global engine OEMs to convert 10-60kW engines.

This technology can be used as a retrofit and supplementary step in manufacturing new engines.