Currently HMRC insists that home made biodiesel (i.e. exempt producers producing less than 2500l per annum for personal use) meets EN14214 in order to benefit from the reduction in road fuel duty.
However testing against EN14214 is very expensive and therefore makes home biodiesel production uneconomic or very risky (in terms of a big bill from the taxman). Why have legislation saying you can produce up to 2500l of biodiesel and then make it impossible to do so.
The insistence on EN14214 also excludes the use of Straight Vegetable Oil (SVO) which requires no processing. Producing biodiesel uses energy and leads to waste products.
Lifting the EN14214 requirement would encourage the use of biodiesel.