FAQ's on bio-liquids for heat


What are bio-liquids?

Bio-liquids are fuels manufactured from renewable sources such as used cooking oil, or from rape seed, wheat or animal fats grown and harvested specifically for making fuel. Bio-liquid is available with 100% renewable content or 100% bio-liquid can be mixed with mineral heating fuels such as Kerosene or Gas oil to make what is commonly known as a “bio-liquid blends”.

Are bio-liquid blends considered to be a long term replacement for mineral fuels

OFTEC estimates that by 2020 over 90% of households in the UK and the Republic of Ireland currently using Kerosene could have switched to using bio-liquid blends. Later it is possible that 100% biofuels could be used for heating following technical development of boilers, burners and oil storage tanks.

Are there standards that bio-liquids have to meet?

100% bio-liquid derived from Fatty Acid Methyl Ester (FAME) should meet the requirements of EN 14214 and be produced under strict quality assurance systems to achieve consistent quality and properties of the fuel.

OFTEC has developed with industry a standard for the blending of 30% bio-liquid with 70% Kerosene entitled “prOPS 24 – Bio-liquid/Mineral Fuel Blend Standard” or B30K.

How do the properties of bio-liquids compare to mineral fuels?

The properties of bio-liquids do differ to that of Kerosene or Gas Oil. Traditional rubber seals in oil carrying components such as oil pumps, filters, valves, etc. will degrade when in contact with bio-liquid. Therefore, such components must be should be replaced for bio-liquid compatible ones when using bio-liquid blends.

How will I obtain the bio-liquid heating fuel?

If the roll out of bio-liquid goes ahead, fuel distributors will be selling the fuel which will be blended at their own “wet depots” and delivered by tanker to end users. If bio-liquid is included in the Renewable Heat Incentive (RHI) they will certify delivery of fuel to an address so that the RHI payment can be claimed from the Government (see below).

Will burning bio-liquid affect the efficiency of my boiler?

Boiler efficiency analysis identified that when an appliance is operating under full load, B30K showed an efficiency loss of 0.5% when compared with kerosene. However, under 30% part load conditions, boiler efficiency was seen to increase by 1.2%. It is worth noting that an appliance would typically operate under part load for the majority of its programmed-on time.

Have bio-liquids been proven reliable?

A bio-liquid fuel project was undertaken by OFTEC and its members in partnership with Carbon Connections, University of East Anglia, ICOM Energy Association and Clean Energy Consultancy. Phase one of the project involved extensive lab research. Phase two involved live field trials at a number of domestic and commercial sites, and no operational issues were encountered.

We believe that bio-liquid blends will prove reliable providing that the conversion of boilers and ancilliary equipment follows strict guidelines; that in most cases the oil storage tank is re-placed; and that the fuel used conforms to prOPS24.

What are the incentives for burning bio-liquid?

Regarding environmental incentive, calculations* show 30% bio-liquid blended with 70% Kerosene (B30K) will produce 28% less carbon emissions than burning 100% Kerosene, 18% lower than LPG, 45% lower than coal and 65% lower than electricity.

Financial incentives could include the recognition of bio-liquid in the regional Government’s proposed Renewable Heat Incentive (RHI) schemes. Under these schemes homes and other buildings that use renewable technologies for heat can apply for regular payments for up to 20 years after installation to offset any cost in converting equipment.

* Source – Technical Papers Supporting SAP 2009 Revised Emission Factors for the National Calculations Methodologies

Is it possible to convert an existing appliance to run on a bio-liquid?

Vaporising burners such as those found in continually burning cookers and stoves are not suitable for conversion.

Pressure jet burners can be converted with relative ease and many OFTEC Member manufacturers have conversion kits available to assist with the replacement of oil carrying components. However, in some cases it may be necessary to obtain a dedicated bio-liquid burner.

How should the storage tank be prepared for conversion?

If bio-liquid is to be put into an existing oil tank, enquiries should be made with the tank manufacturer to ensure the tank material is compatible to store bio-liquid. If it is confirmed as being suitable, the tank should be checked for general condition and cleaned to remove all water, sludge and debris. However many older tanks will not be suitable for bio-liquid blends and will need to be replaced by bio-compatible tanks.

Will bio-liquid conversion affect the warranty on existing components (e.g. tank, boiler etc.)?

Terms of warranty would differ between components and manufacture. If concerns exist, contact should be made directly with the individual component manufacturer for further advice.

How much does bio-liquid conversion cost?

Typically, bio-liquid conversions require replacement of atomising nozzles; fuel pumps and hydraulic components in the burner, as well as flexible oil lines; filters and lever valves in the oil supply. In some cases, the oil storage tank and the complete burner unit need replacing. Therefore, the estimated the cost of conversion is between £1500 and £3500.

Who can I contact to discuss bio-liquid conversion?

Bio-liquids are not currently available. Once they are, OFTEC Registered Businesses and their Registered Technicians would be able to discuss the options with you. They have their competency assessed and are inspected by OFTEC to ensure they are operating in accordance with government guidelines and best practices. They can be located on the OFTEC website or within your local pages, listed under ‘Heating Engineers’.

Would a boiler require more maintenance when converted to run on bio-liquid?

The field trials demonstrated that combustion equipment operating on B30K requires no more maintenance than when operating on 100% mineral fuel oil. This means that service intervals and would remain the same at typically one service per annum.

It should be noted that if an old oil tank has been retained on conversion, it may be advantageous to have oil filters checked frequently after conversion to ensure that they are clear of any debris that may have been brought downstream from the tank.

Can a bio-liquid installation be integrated with other renewable technologies?

Integrating a bio-liquid fuel heating system with other renewable technologies such as solar thermal can be done with relative ease and is no more involved that integrating a mineral oil fuel boiler. Further information is available in our Home Guide on ‘Renewable energy and your oil heating system’.