Scotland ROCs
The banded ROC – mythical bird, unfortunate blunder or somebody’s nest-egg? At a time when we are all being told to save energy, why isn’t efficiency a criterion when subsidising heat and power generation?

Many in the forest industry were taken aback by the remarkably short window of opportunity for
applications to the Scottish Biomass Support Scheme (SBSS) last year, but the Scottish Executive proposal for a banded Renewable Obligation Certificate (ROC) scheme for woodfired electricity generation has hardly prompted any comment at all.

This is surprising, as the proposed changes could cost a lot more money for no extra benefit. A timber industry study in 2007 predicted shortages of supply from the end of that year if all planned
wood-based developments went ahead. Also the Scottish Executive has stated that Scotland has ‘sufficient renewable resources to meet our demand for power several times over’. This suggests that Scotland has plenty of other options for renewable energy, but that supplies of commercial timber may already be spoken for or have other uses.

So why is the Scottish Executive proposing to give millions of pounds of extra money each year to existing wood-fired plants? There may be a case for locally grown biomass fuels like wood to be treated differently from all other sources of renewable energy (RE). The other well known RE technologies, like wind, wave, tidal, hydro’ and solar harvest energy, in the form of electricity, that can be moved long distances without appreciable loss. Timber is bulky and wet when fresh, so the most effective way of using it to displace fossil fuels is to dry, process and burn it locally to generate heat at high efficiencies.

This is an ideal use for timber from gardens, parks, farms, small woodlands and other sources not currently considered commercial. At present each megawatt hour (MWh) of renewable electricity (e) generated receives one ROC. The value of each ROC varies annually due to different factors but is currently worth around £40. The proposal is that this should be changed to encourage particular renewables with tailored rates. The consultation, which closed in early July, concentrates on what Scotland would do differently from England and Wales, but there is no mention of any timber supply problems and a banded scheme is proposed for wood-fired projects by default – see table.

Conventional electricity generation, be it coal-fired, co-fired or wood-fired, makes no use of the
heat produced as a by-product and so is very inefficient. The highest efficiency for a coal-fired plant in the UK is around 37%. By contrast a basic wood-burning stove has an efficiency at least 65%. A modern log, chip or pellet boiler system should have an efficiency at least 85%. And district heating schemes and CHP units are also capable of very high energy generation efficiencies.

To use the E.ON power station at Steven’s Croft as an example, the stated gross generating capacity is 50.4MWe at an efficiency of 31.3%. So the potential energy contained in the fuel consumed is around 161MW per hour. Assuming a fuel moisture content of 35% (wet basis) this is the equivalent of around 50 tonnes per hour or 438,000 tonnes per annum (300,906 tonnes of which effectively go straight up the chimney). In addition to a capital grant of £27 million and the income
from over-inflated electricity prices, the current ROC subsidy could be worth up to £2,016 per hour or £17,660,160 per annum already.

The banded ROC could increase this by £1,008 per hour or £8,830,080 per annum for no additional benefit to Scotland whatsoever. Around 58% of the energy used in Scotland is consumed as heat. Only 15% is used as electricity (other than heating). The SBSS, flawed though it may have been,
resulted in a potential increase of 20 MWt (thermal) of installed capacity for a cost of £7,500,000. Perhaps better use could be made of public money and Scotland’s timber resource if the ROC were removed completely for co-generation plant and capped at the capital cost of all current wood burning schemes except CHP, which could retain one ROC per MWhe or convert to a fixed length feed in tariff. (Contracts for fixed length feed in tariffs would give more confidence to potential
renewable electricity suppliers and still leave government the flexibility to adapt the payment rates for future projects.)

The many millions of pounds thus released could then be used for a massive investment in domestic and community scale wood-fired heating equipment and supply chain development which could result in tangible environmental, economic and social benefits for every community in Scotland.
If the proposed changes to the ROC could result in one company receiving more than the total SBSS in additional subsidy in less than one year for no additional benefit, then perhaps the whole ROC scheme needs to be reassessed?

Indeed, if there are concerns about supplies of commercial timber or alternative markets, what benefit could be expected? If this were a banana republic there might be cause to look for a malevolent intelligence that is benefiting from the way wood-derived energy projects have been treated in Scotland. Such things couldn’t happen in the UK – could they?

The new ROC bands for wood-fired electricity generation:– 0.25 ROC per MWhe Electricity made by co-firing wood and coal in a conventional power station. 1.50 ROC per MWhe Electricity generated in a dedicated biomass-fired power station. 2.00 ROC per MWhe Electricity generated from short rotation coppice. 2.00 ROC per MWhe Electricity generated in a combined heat & power (CHP) unit. Links:– www.scotland.gov.uk/Topics/Business-Industry/Energy/19185/ROSCons08Intro www.sepa.org.uk/pdf/ppc/ppd/archive/PPCA/1011415_1417/