When looking at the certificates issued by Ofgem all seems simple and straightforward. Each station has certificates issued based on output and various factorings. Simple. Except it isn’t. certificates can be revoked (no explanation is provided so it’s unclear why), expired or retired. Some are eventually redeemed. along the way things are just as unclear.
As an example, look at the Glyndebourne Wind turbine REGO issuance (http://www.variablepitch.co.uk/station/392/REGO/). In January 2012 there were 2 sets of certificate issued, both for 158MWh of production and both with the same certificate numbers (click on the i to see the details). The only difference appears to be that they were issued to different holders. Hmm. Similar patterns are visible for the rest of the periods covered until July 2012 when things got more predictable.
Why does this matter? Well, by simply looking at the certificates issued in a naive manner such double issuances would lead to double counting so to use the collected data a smarter approach is needed. In fact looking at the data things sometimes get even stranger.
For instance, look at the REGO issuance for An Suidhe in August 2012 (http://www.variablepitch.co.uk/station/98/REGO/). It appears that only 334 certificates have been issued, but the process of arriving at this number is anything but straightforward.
Until I changed the method of storing and collecting the certificate data for Variable Pitch these changes weren’t as obvious or as easy to view. Now that the data is easier to work with I’m working towards new processing that should allow the site to better track the correct output levels and who has ultimately ended up with the certificates. It’s proving to be a difficult problem due the variety of possible paths that can be taken, but hopefully I’ll get it working before long.
Watch this space.