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Archive for August, 2009

Biodiesel will almost certainly be a recognised fuel under to upcoming changes to building regs, opening the door to biodiesel CHP as a way to meet increasingly stringent limits on emissions. While a number of big urban developments will breathe a sigh of relief at the news, it’s not all plain sailing. (more…)

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I’ve just finished watching the first of three episodes of The Future of Food on iplayer. In it there’s a fascinating interview with Hilary Benn, secretary of state for DEFRA. Fascinating not because of what he says, but what he doesn’t say. On this programme about the upcoming global food shortages (mainly due to fuel prices, water shortage, and changing climate), he says:

We know we’re going to have to grow more food with a changing climate and probably less water being available… I think looking at what happened last year, the food riots, the rise in prices, we’ve got to take responsibility now to ensure that people have enough food to eat.

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Isabelle McKenzie has put up a very useful post on the Fontenergy blog describing the practicalities of third party access for private wire networks. She starts with background info on the Balance and Settlement Code before going on to outline the two main strategies for allowing third party access.

Will private wire always be an option for small schemes? Maybe not, but until DECC and OFGEM can come up with an alternative, these schemes will need to tread carefully to make sure they’re adhering to best practice and not being anti-competitive. Have a look.

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Following on from discussion about planning reports last week, here’s a chart I put together showing roughly how much PV you can fit on a flat roof. It’s based on the formulas described by Volker Quaschning, the German Godfather of Sol (Thank you! I’ll be here all week. Try the crab).

Solar-shading

The shading angle is the angle from the bottom of the panel behind to the top of the panel in front. As a rule of thumb, you can use the height of the sun at noon on the winter solstice – for London, this is about 15°. Utilisation factor is the ratio of panel area to roof area.

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The new SAP has a revised carbon intensity for grid electricity (set in the consultation at 0.591 kgCO2/kWh, up from 0.422). This has a big impact on the resulting carbon emissions from heat pumps, in most cases making them higher than emissions from the worst boiler you can legally install. This goes for both air source and ground source.

You can see from the graph above that at a grid carbon intensity of 0.591 even a GSHP with a COP of 4 is struggling to outperform an 86% efficient gas boiler. The real world COPs seen at Barratt’s Chorley scheme (2.6 for GSHP) and recent field trials by Mitsubishi  (3.0 – 3.4 for ASHP according to a letter from Mitsubishi in the latest CIBSE mag) mean that heat pumps would emit significantly more carbon than the boiler.

And yet in the low carbon transition strategy, DECC state that heat pumps will be eligible for the Renewable Heat Incentive (pdf – see para 1.22), rewarding them for being a renewable energy source! What the hell are they thinking?

Here’s how I did the numbers:

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links for 2009-08-07

  • The UKGBC's task group looking at PAYS has published its report (look for the link on the home page). Thankfully, it looks like councils (rather than the Big 6) are the preferred collection mechanism. But the report seems to swing between 1) admitting that significant contribution from govt or end users will be required and 2) claiming that any subsidies will be "modest" and merely an incentive to "encourage uptake". Reading through now with more to follow.
  • Great article from Forum for the Future. "To have an all-electric paradigm shift within the next decade, says Richard Gott, we’ll need some sort of major disruption to petroleum supplies – like a war, or some other huge economic or climatic disaster." How about just peak oil?

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For consultants, energy reports for planning are fantastic: a bit of SAP, a few benchmarks, some spreadsheet magic, and hey presto you’re sending an invoice. But the contents of the energy report can have huge implications, in some cases committing the scheme to commercially or legally impossible strategies, causing delays and increasing costs later in the programme. Here are a couple of examples:

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