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Tag Archives: AD

Green heat in the UK

by Dave Elliott

‘Heat is very difficult to decarbonise and no consensus is yet reached on the mix needed for the long term and you will have seen that from the various different reports on the subject.’  So said the then UK Minister of State for Energy, Baroness Neville-Rolfe, at the Heat Summit last December, with the next phase of the Renewable Heat Incentive (RHI) central to the agenda. There certainly are some competing options, including community-wide heat networks, green gas supply networks, biomass and solar home heating and domestic heat pumps powered by electricity.

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Green heat and energy saving

By Dave Elliott

Heat supply is one of the key weak links in the UK government’s attempt to meet the EU-imposed 15% by 2020 renewable energy target. That target still applies – until the UK finally leaves the EU, if it ever does fully. Although there is talk of green heat networks, for the moment the focus is mostly on direct green heat supply for business and private consumers, and there are some changes underway. The UK’s Renewable Heat Incentive (RHI) has escaped cuts so far. Indeed it is set to expand, but the government wants to restructure it to keep energy costs down for consumers and get better value for money. So, concerned also about impact on food growing, it wants to support the use of food and farm waste-based biomass feedstock rather than crop-based feedstocks for biogas production in Anaerobic Digestion (AD) plants. It has also proposed cutting support for solar heating since it is not seen as good value for taxpayer support.

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BREXIT impacts and implications

By Dave Elliott

The overall context for UK energy policy and the prospects for renewables have taken something of a hit following the narrow referendum vote to leave the EU, with the climate for new investment looking uncertain. In what may become a familiar pattern, leading German engineering company Siemens has put new wind power investment plans in the UK on hold, and more may follow if the economy continues to falter. It certainly looks grim: www.theguardian.com/environment/2016/jun/28/leave-vote-makes-uks-transition-to-clean-energy-harder-say-experts  and http://uk.reuters.com/article/uk-britain-eu-renewables-idUKKCN0ZH4CZ

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The RHI to be ‘reformed and refocused’

By Dave Elliott

The UK’s Renewable Heat Incentive (RHI) was introduced to support households, businesses, public bodies and charities in moving from conventional forms of heating to renewable, low carbon sources of heat. It has escaped cuts so far, indeed it is set to expand, but the government wants to restructure it to keep energy costs down for consumers and get better value for money. It expects spending on the RHI to rise from £430m in 2015/16 to £1.15bn in 2020/21, but says it wants to promote wider access and make project more affordable, ‘by firmly controlling costs’.

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Waste not, want not

We produce of lot of waste. Some is a potential source of energy. That may even include the carbon dioxide produced from combustion.

We usually treat carbon dioxide as a problem. But it can also be a solution. There are some interesting new ideas about using it to make fuels. One option is to use it to enhance algae growth. This can of course be done, in principle, with any bio-crop in large glass houses or other gas-tight enclosure: gas-engine exhaust is already used in commercial glasshouse horticulture for tomatoes etc, e.g. in Holland. But algae absorb CO2 more rapidly. MIT’s carbon-capture and algae-bioreactor system is interesting. http://web.mit.edu/erc/spotlights/alg-all.html (http://web.mit.edu/erc/spotlights/alg-all.html) However there are evidently issues of maintaining efficient reactions, and the US company involved with this, GreenFuel Technologies, evidently has had financial problems. But trials by Sheffield University, using captured CO2 (from Tata steelworks near Scunthorpe) bubbled through algae tanks, are showing some promise: www.thisisscunthorpe.co.uk/news/algae-turn-billions/article-2947359-detail/article.htm

Meanwhile Swedish utility Vattenfall has launched a pilot project using algae to absorb greenhouse-gas emissions from a coal-fired power plant in eastern Germany in a €2m trial run. Half the funding for the MiSSiON (Microalgae Supported CO2 Sequestration in Organic Chemicals and New Energy) project comes from Vattenfall, the other half from state and EU subsidies. The flue gas emitted at the Senftenberg brown-coal fired plant is being pumped through a broth using algae cultivated in 12 plastic tanks. The biomass produced can be used to produce biodiesel, to feed biogas power plants and as a nutritious supplement in fish food.

In a somewhat similar approach, Carbon Sciences Inc. says it’s developing a technology to transform greenhouse gases into liquid portable fuels, such as gasoline, diesel and jet fuel. ‘We are developing highly scalable clean-tech processes to produce liquid fuels from naturally occurring or human-made greenhouse gas emissions. From sources such as natural gas fields, refinery flare gas, landfill gas, municipal waste, algae and other biomass, there is an abundant supply of inexpensive feedstock available to produce large and sustainable quantities of liquid fuel to replace petroleum for global consumption, thereby eliminating our dependence on petroleum’. www.carbonsciences.com

Much more radical is the idea of reacting CO2 with hydrogen produced by electrolysis using electricity from wind turbines, to make methane and synfuels. See the UK ‘Air Fuels’ project www.airfuelsynthesis.com(http://www.airfuelsynthesis.com) and the various German/EU projects e.g CO2RRECT http://co2chem.co.uk/carbon-utilisation/co2rrect
I’ll be looking at this ‘wind-to-green-gas’ idea more in my next blog.

Bio-waste

We also treat municipal and domestic solid waste as a problem, sometimes just letting it rot in landfill sites producing methane – a powerful greenhouse gas. Some of that gas can be and is captured, providing a cheap renewable fuel, but if it’s burnt to generate power then you get carbon dioxide, although that could be captured and stored. Then the energy would be carbon neutral or even carbon negative, given that the production of food/farm waste has involved the absorption of carbon dioxide.

However, there are also other approaches, such as controlled anaerobic digestion of food/farm waste algae, with the emphasis on high-value food products rather than energy production. For example, start-up company Merlin Biodevelopments based in North Wales has devised a new way of growing protein-rich algae from waste food and cow slurry, which can be used in high-protein food products for human and animal consumption. An array of reactor tubes, in which the algae are cultivated, has been built in a polytunnel at the Moelyci Environmental Centre, Tregarth, near Bangor. So far Merlin has invested £500,000 in the project, including R&D grants worth £160,000 from the Welsh Assembly Government. It’s designed its own low-cost micro AD plant, and its single 30m long polytunnel can produce 20 tonnes of algae a year. A second plant is due to open in south Wales soon and Merlin expects to be producing 1,000-2,000 tonnes by 2013. They say a 210 sq m polytunnel can produce as much protein in a year as 10 sq km of top-grade agricultural land. In a side project at Moelyci, Merlin is also investigating the value of processing AD residue into high value fertiliser using the algae system.

Using food waste for AD is clearly sensible. As I’ve noted before, Gwynedd Council are backing a new AD plant, which will process around 11,000 tonnes of food waste each year; converting it into renewable electricity and biofertiliser for use on nearby farmland. The food waste will be collected from local homes and businesses via a collection scheme run by Gwynedd Council. The new plant will replace the existing landfill site. It will be the second waste-fed anaerobic digestion plant built in Wales, following the construction of the Premier Foods plant last year near Newport.

In addition, food waste from homes in South Gloucestershire is now also being converted into renewable energy and organic fertiliser at a single site via AD. Food collected at the kerbside is being sent to an anaerobic digestion plant in Oxfordshire to be broken down by bacteria into useful gases and organic materials. The long-term arrangement with operator Agrivert, brokered by the council’s waste collection contractor Sita UK, will see about 6,000 tonnes of food waste processed each year – equivalent to the weight of rubbish carried in 600 full refuse lorries. Agrivert manager Harry Waters said the company would expect to capture two million kilowatt hours of renewable energy from that amount of food waste every year. He said: “That is enough to power more than 400 family homes and produce organic fertiliser which will be used by farmers to grow food on more than 700 acres of land. Moreover, we capture a million cubic metres of methane that would otherwise be released to the atmosphere.” http://www.agrivert.co.uk/

One way or another the AD biogas option looks likely to become increasingly important. The Anaerobic Digestion and Biogas Association recently said the Chancellor’s efforts to give shale gas a helping hand with a ‘generous tax regime’, would be better spent on other forms of gas which are renewable, like biogas. The ADBA suggests biogas from anaerobic digestion (AD), ‘which can provide energy security at a lower cost and, since it’s renewable, with far lower carbon emissions and environmental impact than more experimental technologies like shale gas. AD can be scaled up fast and cheaply and with the right support could generate 40 TWh of biogas, equivalent to 10% of
the UK’s domestic gas demand, at the same time as boosting economic
growth and creating 35,000 jobs.’ www.adbiogas.co.uk

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Biomass – on a slow burn

The Climate Change Committee’s report on bioenergy earlier this year was somewhat more cautious than many previous studies, arguing that, at best, the UK might only get 10% of its energy from bio-source by 2050. The CCC saw bioenergy as a scare resource, with significant constraints, not least land use. This of course is a global issue, with for example, in terms liquid biofuels, there being many concerns about the environmental and social impacts of large plantations around the world. It’s not just direct land use, it’s the impacts of land use changes (‘ILUC’) that matter, which CCC say must be included, though they are hard to assess. But if at least a 50% emission reduction, below that from fossil fuels, is set as a target, there’s less room for manoeuver.

When it comes to solid biomass for heat and power production, things get a little easier in terms of land use. CCC say ‘Our core scenarios focus on the use of abandoned agricultural land’, with a range of energy crops being viable: ‘We assume in the longer term dedicated energy crop feedstocks are a mix of fast growing trees and grasses, as these crops are potentially more suitable to land of low productivity, have low lifecycle emissions and can be converted for use across the range of sectors’. But CCC see Carbon Capture and Storage as vital in many cases: ‘If CCS is not available at the scale envisaged, the amount of bioenergy required to meet the 2050 target would have to be significantly higher than 10% of primary energy demand, and would imply land use change exceeding currently estimated sustainability limits.’

They also warn that ‘given limits on domestic supply, much of the forest biomass for power and heat used in the UK will have to be imported’. Nevertheless they feel able to conclude that ‘Scenarios for global land use which take account of required food production suggest that a reasonable UK share of potential sustainable bioenergy supply could extend to around 10% (200 TWh) of primary energy demand in 2050. However, it would be unsafe at present to assume any higher levels of bioenergy supply, and even the 10% level might require some trade-offs versus other desirable environmental and social objectives (e.g.through energy crops production encroaching on land of high biodiversity value).’ But they want tighter limits: ‘the threshold for use of biomass to meet the RO should be tightened to 200 gCO2/kWh. This would represent a significant enough saving relative to gas-fired generation, allowing a margin for emissions from possible indirect deforestation.’

Clearly they do not see biomass as likely to play a major role, although they suggest that there might be range of ‘sensible smaller-scale local uses’ – such as making use of old cooking oil to run buses, using food or farm waste in anaerobic digestion plants, or using woodchip from tree surgery waste in biomass boilers. Pretty marginal then, with CCC concluding ‘The role for use of biomass in heating buildings is likely to be relatively limited in the longer term, given alternative low-carbon options such as air-source and ground-source heat pumps. Where these are not feasible, there may be opportunities for district heating using waste heat from large-scale low-carbon thermal power plants (potentially including biomass CCS) or CHP using local waste or biomass, and for biomass boilers using local biomass in rural homes.’

This may be too dismissive a view. Certainly, in practice, biomass/biogas energy options are still struggling to get going on a significant scale in the UK, with objections still emerging to some large-scale power projects, but some are still moving ahead.

E.ONs controversial 150MW biomass power station in the Royal Portbury Docks, near Bristol, has got the go ahead, despite concerns about its part reliance on imported virgin wood. It will also use dedicated energy crops, and locally sourced waste wood. E.ON has said it would set up a community investment fund, contributing £50,000 per year for charitable and educational community projects in the area, while a further £75,000 would also be set aside to trial green buses and improve cycle routes in the area.

However, E.ON told BusinessGreen that it was reviewing its plans for this and other renwable energy projects, in light of proposed changes to subsidies offered under the government’s Renewable Obligation scheme. Drax also seem to be having second thoughts again about their biomass co-firing projects, complaining that there was not enough RO support

Meanwhile, Sheffield Council is looking at plans for a £20m waste wood CHP project in the Holbrook area , following on from the agreed E.ON’s £120m 30MW waste wood biomass plant on the site of the old Blackburn Meadows power station next to the M1, now under construction. In addition, RES has plans for a 100MW biomass plant in Northumberland on Blyth River.

An energy from waste/biomass complex has also been proposed for the Ince Park development located at the Manchester Ship Canal, as a joint venture between Peel Environmental and Covanta Energy. Construction of the EfW facility is set to begin soon aiming for operation in 2015. Peel Energy has also got planning permission for a separate 20MW biomass energy facility on the site, with construction scheduled to start early next year. Plants like this, which involve combustion, are often opposed by environmentalists due to possible emissions (especially if wastes are used) and also the land-use/ biodivesity implications of large scale biomass growing/importation

In Wales, in a novel project which should avoid these issues, BiogenGreenfinch have been appointed by Gwynedd Council as the preferred bidder for the construction of a new green energy plant which will take council collected food waste and turn it into renewable energy via Anaerobic Digestion. The new AD plant, which should be running soon, will process around 11,000 tonnes of food waste each year; converting it into renewable electricity and biofertiliser for use on nearby farmland. The food waste will be collected from local homes and businesses via a collection scheme run by Gwynedd Council. The new plant will replace the existing landfill site currently situated in Llwyn Isaf and should play a major role in helping the Council meet their statutory recycling targets. It will be the second waste-fed anaerobic digestion plant built in Wales, following the construction of the Premier Foods plant last year near Newport.

In this case, the biogas is burnt to produce electricity, but AD biogas can also be added to the gas main, with, despite CCC’s rather negative assessment, the prospects for ‘green gas’ from waste AD being increasingly seen as a new possible direction for green heat supply-in Germany especially. For more: www.biogas-info.co.uk.

While CCC may be a little sniffy about biogas, the new DECC/DEFRA/DfT Bioenergy Strategy is a lot more positive, as is the parallel DECC Heat Strategy. Although they do not see biogas playing a role in domestic heating directly, they do envisage biomass and biogas being used for community heating via CHP plants linked to district heating networks. I will be exploring this, and the green heating options. in my next few Blogs.

CCC report: [www.theccc.org.uk/reports/bioenergy-review
](http://www.theccc.org.uk/reports/bioenergy-review)

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