Combined knowledge

07 May Combined knowledge

Combined heat and power (CHP) systems have the potential to reduce carbon emissions significantly, as well as being able to displace a proportion of Grid-supplied electricity with locally generated, lower carbon electricity. Paul Riding, head of innovation, Calor, discusses.

With residential and commercial developers increasingly under pressure to minimise emissions from new-build and refurbishment projects, the need to specify both low-carbon and reliable solutions is of paramount importance.

With a growing insistence from commercial clients for building firms to achieve ever higher BREEAM (Building Research Establishment Environmental Assessment Method) ratings, new technologies such as combined heat and power (CHP) are becoming increasingly important components in the technology solutions mix.

BREEAM is the most widely used measure of environmental assessment for non-domestic buildings. Over 200,000 buildings are already BREEAM-certified in the UK, and a further one million registered for certification. Businesses must be seen as acting responsibly and taking decisive action to reduce carbon output, and a BREEAM assessment rating is a good place to start.

There are an estimated two million homes and businesses in the UK located in non-mains gas areas, plus all the new-build properties constructed each year. Improving the energy-efficiency of these buildings is crucial to helping the government achieve the UK’s carbon-cutting obligations.

Fortunately there are a number of low-carbon heating options available to specifiers working on non-mains gas building projects, and CHP is one of the more exciting ones.

CHP is a technology that generates relatively clean, low-carbon electricity on site, using gas (LPG in non-mains gas areas) to power an engine, which in turn drives a generator. The considerable heat generated from these two components of a CHP system is siphoned off and used to thermally heat the building that the CHP unit serves. This simultaneous generation of both electricity and thermal heat results in an incredibly efficient system.

Because LPG is low in carbon and also very clean compared to other fossil fuels, such as oil, the aforementioned attributes of CHP technology are becoming increasingly recognised by forward-thinking construction companies and now by the government. This is why we expect CHP to feature more in future construction projects.

For example, those business premises that harbour a particular electrical/thermal demand to match the working limits of a specific CHP system will, without doubt, benefit from the technology – especially where CHP is replacing an old, inefficient oil heating system.

LoadTracker, a modulating, LPG-fuelled, combined heat and power (CHP) unit from SAV Systems is an example. This modulating CHP system varies its electrical and heat outputs dynamically via an automatic monitoring system that delivers heat and electricity according to the fluctuating needs of the building throughout any 24-hour period. As a result, the system is highly efficient.

This is in stark contrast to centrally generated power from Britain’s coal/oil-fired power stations, which typically operate at below 40% efficiency. The SAV unit’s ability to modulate heat and electrical production is more advanced than most CHP systems, which deliver fixed outputs that have to be manually adjusted to suit a building’s seasonal heat/power requirements. This flexibility allows SAV’s CHP system to deliver carbon savings of over 23% compared to oil boiler installations. Such savings in CO2 contribute to improved BREEAM assessment ratings.

SAV’s LPG-fuelled LoadTracker CHP features a modified Toyota engine with service intervals of 8,000 hours and noise emissions of just 49dB(A) – resulting in a reliable, low-maintenance system that is quiet enough not to require any special soundproofing at the installation point.

For homes and businesses with smaller energy loads, an alternative CHP solution should be considered. New-build domestic properties in rural areas seeking to meet post-October 2010 Building Regulations should consider the micro-CHP unit from Baxi Ecogen. It provides a simple solution for developers, but also offers the homeowners a system that not only produces fewer emissions than a Band A boiler, but can also qualify for Feed-in Tariffs (FITs).

The FIT is a government incentive that pays the householder for locally generated electricity plus any surplus electricity that is automatically fed back into the Grid by the CHP system. The potential attractiveness of CHP to prospective house-owners may also work as a key selling point for builders.

The LPG Baxi Ecogen unit looks like a normal wall-hung boiler but, as well as providing highly efficient central heating and hot water, it is the first commercially available domestic boiler in the UK that can generate electricity, and represents a step change in efficient fuel use.

Using micro-CHP to power homes means that consumers buy less electricity from their supplier, get paid for what they produce and, consequently, can look forward to lower bills and a smaller carbon footprint.

Although designed for domestic use, the Ecogen’s 24kW heat capacity and 1kW electrical output is also ideal for many commercial premises such as pubs and small hotels.

The LPG Baxi Ecogen unit, which is already available to homeowners on mains gas, is now available to those using LPG in off-mains areas and could cut annual fuel bills by up to £1,0551 as well as potentially earning households money.

With such a broad range of LPG-fuelled, low-carbon solutions, there has never been a better time to invest in technologies that can cut costs as well as carbon. But not only is CHP an ideal sustainable solution for minimising carbon emissions in non-mains gas areas; there are genuine merits to choosing LPG as a fuel.

Here are some reasons for choosing LPG as the main heating fuel for domestic or commercial developments in non-mains gas areas:

• LPG has the lowest carbon emissions of all fossil fuels available in rural areas – for example, it emits more than 10% less carbon dioxide than heating oil2

• LPG is cleaner burning, with virtually no soot and minimal sulphur emissions

• LPG is incredibly versatile – it can fuel central heating and water heating as well as real flame fires, portable heaters, ovens and cookers – giving the controllable flame you only get from gas

• LPG storage is flexible – it can be stored above or below ground in bulk tanks or in cylinders. Calor has even developed Think Tank technology that arranges automatic fuel top-ups

• LPG tanks usually remain the property and responsibility of your LPG fuel provider, so maintenance is the responsibility of the company

• LPG can be used to supplement renewable hot water and heating solutions, such as solar power.

1. Based on official PAS67 and APM results, April 2021 – www.energysavingtrust.org.uk – and compared to a SEDBUK Band G-rated boiler. The savings calculation is only an illustration and actual savings may vary considerably dependent upon individual circumstances and usage profiles
2. From SAP 2009 – www.bre.co.uk/sap2021