Air Quality and Decentralised Electricity Policies

Environmental goals can be achieved with good product choice.

The new Totem range of Combined Heat and Power units have NOx emissions of less than 10mg/kWh. This is less than 5% of the average NOx emission rate associated with the production of UK electricity and about 1/3 that of the cleanest condensing boilers available. The technology built into the Totem range to control emissions is significantly better than anything else available.

The Royal College of Physicians released a study last year that attributes over 40,000 premature deaths per year to poor air quality in the UK. Indeed, it is impossible to pick up a newspaper or watch the nightly news without a story about the poor air quality in our cities and the negative impact on life this has.

As an environmentally conscious company heavily involved in emissions policy we applaud the Mayor of London for his work on air quality. However, it is evident that the majority of the focus is on traffic emissions and we feel that due to the current level of air pollution it is necessary to review all modern guidance and policies including those related to energy use in buildings. In the recent report Up In The Air—How to Solve London’s Air Quality Crisis – Part 2, authored jointly by Policy Exchange and Kings College London, it is reported that in central London 38% of polluting emissions are the result of gas usage in buildings, and as traffic emissions are reduced this percentage increases. The resulting question that needs to be answered is whether Carbon Dioxide emission reduction legislation leads to an increase in air pollution? An analysis of the legislation shows that in some circumstances this can happen.

In the UK national and local governments are promoting on-site production of electricity with waste heat capture for three main reasons. First, it reduces reliance on the UK electric grid which has become oversubscribed. Second, it reduces CO¬2 emissions and aids the UK in attempting to meet its environmental commitments. Finally, CHP makes a good business case: there is no other low or zero Carbon technology with a payback time as short as CHP without government incentives. These three key benefits make CHP the first choice of the UK government to reduce Carbon Dioxide emissions. This can be seen in the London Plan’s Policies 5.5 and 5.6 which promote Decentralised Energy Networks and the Building Regulations Part L calculation methodology which rates CHP very favourably.

The unintentional consequence of producing electricity at the point of use is that it relocates the emissions of production within urban areas. Power plants are primarily located outside of city centres to limit their polluting effect. Where CO2 emissions are judged on a countrywide or worldwide scale, the emissions of Nitrous Oxides have local consequences. NOx emissions are the main contributor to air pollution. The NOx emissions from a power plant, although very high, are not in densely populated areas and they disperse and dilute with minimal health consequences. Combined heat and power systems reduce CO2 emissions by 25%-30% with countrywide benefit regardless of where they are located, but the local consequences of their NOx emissions must be considered. If a CHP system with equivalent NOx emissions to a power plant is installed in city centres, where the pollution levels are already at elevated levels, it will have a terrible impact on quality of life and health.

With modern technology this is no longer the end of the story. The current discussion around this topic implies that the designer must choose a decentralised network at the expense of air quality or avoid decentralised electricity production to limit pollution. The Totem CHP range, with advanced control over the combustion process and NOx emissions, does not support this thinking. An accredited laboratory has certified that the Totem T20 and T25 emit only 4.8 mg NOx/kWh of gas input and the Totem T10 emits 7.5 mg/kWh. Utilisation of a Totem CHP in city centre decentralised electricity production has no measureable negative effect on air quality. In normal working conditions the Totem is so much cleaner than the ‘average’ CHP unit (240mg/kWh) that choosing it is the equivalent of removing 200 commuting modern diesel cars from the roads.

As our cities struggle with the dilemma of reducing air pollution and guaranteeing a reliable electricity infrastructure the Totem is able to successfully align clean air and decentralised energy policies. With a focus on standard, mass produced automotive components the Totem is value for money and can provide this technology within the same price bracket as the older, more polluting CHP units. There are no barriers to choosing the Totem and although legislation does not prevent the installation of high-polluting CHPs in urban environments, responsible designers should be selecting the technology with the least impact on air quality now. The decentralisation of electrical production is already happening; in London alone, approximately 200MW of capacity has been installed with a goal to add 1GW more by 2025. It is vitally important that the next 1GW is cleaner than the first 200MW have been.

Additional benefits of the Totem include highest total efficiency without requirement for a separate exhaust heat recovery system. The Totem includes a built in condensing heat exchanger delivering total net efficiencies of 107.1% with 31.5% electrical efficiency. Furthermore, the Totem has an automatic oil change system which reduces wear on the engine. Combined with Adveco service packages the efficiency of the Totem unit can be guaranteed to provide over 90% of the design electrical power output for 10 years. No other CHP can guarantee this level of performance.