Hot gossip, cold facts

Published:  10 March, 2009

If the solution to the problem of climate change is sustainability, then the solution itself must also be sustainable, says Mark Northcott. That is why he strongly advocates the specification of condensing boilers in heating systems.

With all the depressing statistics generated by the global financial meltdown, it is heartening to be able to present more cheerful figures relating to the environment.

My company has calculated that if just 500 schools in the UK used condensing boilers for their heating, they could produce annual gas savings of 4 194 500 m3 and electrical savings of 352 000 kWh, generated at the power station at only 33% efficiency. This equates to impressive annual financial savings of £1.2 million compared with pressure jet boilers. These savings would be around 25% higher if the comparison was made against old atmospheric boilers.

Condensing technology is inherently more sustainable than other forms of heating, predominantly for two reasons.

• Low NOx and carbon emissions, which help to combat global warming.

 

• Dramatically improves a building’s energy efficiency, thus reducing fuel bills.

Condensing boilers are also relatively cheap to buy, They can be sited virtually anywhere and comprise familiar, well-tested technology. They generally have excellent fault diagnosis facilities and are easy to install (making them more likely to be fitted than many of the so-called ‘renewable’ technologies that are appearing on the market).

 

These combined advantages result in a win-win; not only will more jobs get completed because condensing technology is cheaper and easier to install, but the energy efficiency of the technology will also release money for even more energy saving and measures to reduce greenhouse gases.

After all, projects that don’t go ahead because of excessive cost save no greenhouse gases, and strategies that are too costly per project are not sustainable strategies

So sustainability must be at the heart of any enlightened environmental initiative. But this begs a fundamental question: What exactly is sustainability?

The most commonly accepted definition came in 1987 from the United Nations World Commission on Environment & Development. The Brundtland Commission report, which resulted from a meeting of this organisation, came up with this definition. ‘Sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs.’

This clearly implies that the first rule of any sustainable technology is that it does not generate unacceptable emissions. Condensing boilers offers potential NOx and carbon savings of more than 80% and up to 50%, respectively. See the box for how favourably this compares with alternative heating sources.

However, emissions are only part of the story. More than half of all energy losses

occur between the power station and the end user’s property. Losses in transmission and distribution networks make siting flexibility a critical sustainability consideration in the specification of any heating product.

Network losses are estimated to amount to 55% of electricity generated, making the distribution network the single biggest consumer of electricity. So, anything that manufacturers can do to offer more local power generation is bound to help increase its sustainability.

That is what makes micro combined heat and power (microCHP) such a potentially powerful development. MicroCHP units are essentially condensing boilers that use some of the waste heat to generate electricity locally, using a Stirling engine.

Broag-Remeha is currently conducting field tests of this technology and expects to launch a practical microCHP unit within the next year. This will make a significant further contribution to energy efficiency by eliminating the transmission losses associated with conventional power generation.

But the benefits don’t stop there. MicroCHP is a low- to zero-carbon (LZC) technology, and planning regulations increasingly require the use of LZC sources to reduce CO2 emissions. On top of this, appreciably less electricity is required, resulting in a 20% reduction in total energy costs.

These are striking results and could herald the start of a new revolution in heating. Watch this space.

Mark Northcott is director — commercial products at Broag.

Condensing benefits condensed A condensing boiler will always have a better operating efficiency than a conventional non-condensing one due to its larger and more efficient heat exchanger. It will also result in fewer emissions of greenhouse gases such as carbon dioxide and NOx. Our own Remeha boiler, for example, increases the value of the end user’s carbon and NOX saving pound by producing NOx at <37 mg/kWh at 91% gross calorific value (GCV) compared with a traditional atmospheric boiler nearing the end of its service life which pumps out NOx at around 180 to 250 mg/kWh at 50% GCV. A pressure-jet boiler’s NOx emissions are around 160 to 220mg/kWh at 80% GCV, and a new wood-burning boiler using pellets as fuel produce NOx of around 220 mg/kWh at 80 per cent GCV. NOx gases — comprising NO, NO2 and N2O — are many times more effective at trapping heat in the atmosphere than carbon dioxide and persist in the atmosphere for about 150 years. So the NOx gases produced today will affect the atmosphere until the year 2159. Anything that can be done to mitigate their effects has to be good for the environment, and condensing boilers do just that.



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