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Tag Archives: biogas

Talking renewables up – and down

by Dave Elliott

A meta-analysis by NREL staff, comparing the various quantitative scenarios that have emerged with very high penetrations of Renewable Energy in the power system for a range of countries and regions around the world, concludes that they show that renewables  ‘can supply, on an hourly basis, a majority of a country’s or region’s electricity demand.’ www.sciencedirect.com/science/article/pii/S1364032113006291

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Bioenergy is good

by Dave Elliott

In a new book ‘The Sleeping Giant Awakens-Bioenergy in the UK’ (Alba press), Stewart Boyle, a former green activist turned energy consultant and woodland owner, who has worked in the bioenergy sector for 12 years, sets out a strong critique of the current status of bioenergy in the UK. Controversially, he takes issue with the conclusions of some green pressure groups who have of late opposed reliance on biomass. ‘Having reviewed the science and the arguments, I feel that some of the NGOs have lost the plot on bio-energy and are using really bad science without thinking through their long term energy strategy.’  He claims the UK could get at least 10% and maybe over 20% of its energy frombioenergy in heat, transport, power and bio-chemicals.

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Renewable methane

There has been a lot of interest in developing national energy systems using renewable methane, rather than fossil methane, or even electricity, as a major energy carrier. Unlike electricity, methane can be stored and can also be transmitted with lower energy losses. In the UK the natural gas grid actually handles about four times more energy than the electricity grid. Moreover, if the methane is generated using green energy sources then it’s carbon neutral, and if it’s generated from bio-sources and also has CCS added, then its combustion can be carbon negative.

Biomethane produced from biomass/waste via AD is one option and this can be added to the gas grid. It’s an idea that’s spreading across the EU. See: www.greengasgrids.eu/sites/default/files/files/ 120529_D2_2_Overview_of_biomethane_markets_rev1.pdf

However, there are also more advanced ideas. Germany has been pushing ahead with ‘green gas’ production, generating hydrogen via electrolysis, using excess wind-derived electricity. The hydrogen gas can be used as a fuel direct (e.g. in fuel cells or gas turbines) for electricity production, or added to the natural-gas grid, or used in vehicles. It can also be converted into other fuels. Audi will be launching their ‘e-gas’ vehicles in 2013, running on methane made from wind-derived hydrogen in combustion engines designed for gas use. E.ON has started work on a €5m wind-to-gas pilot project for gas-mains injection. But the hydrogen can also be converted to methane or other syn fuels, using CO2 captured from the air or from power plant exhausts, once again for use in vehicles, for heating or for power production. In effect it provides a way to store excess wind and also capture CO2. The later concept is central to the CO2RRECT project http://co2chem.co.uk/carbon-utilisation/co2rrect

There are several more complex versions of these ideas currently being promoted. In one variant explored by the Fraunhoffer institute, green hydrogen and captured CO2 is used to upgrade biomasss feed stock, the argument being that this will allow for the production of higher value fuels without having to use so much land area for biomass growing. http://www.iset.uni-kassel.de/abt/FB-I/publication/2010-088_Towards-renewables.pdf

There are other possibilities. Enertrag AG is operating a 6MW wind-to-gas plant 120 kilometers north of Berlin, with the help of its partners, Vattenfall, Total and Deutsche Bahn. One option is to mix the hydrogen with biogas made from local corn waste to feed into CHP/ cogen plants, which produce electricity and heat. The power can be fed back into the grid at times when little or no wind is available, while the heat can be fed into district heating networks. During periods of low wind, the biogas plant can run on biomass alone. Enertrag is also feeding hydrogen gas direct into the natural gas grid and Greenpeace Energy is already buying some of this ‘windgas’ to sell to households. And of course it can also be used in vehicles: www.enertrag.com/en/project-development/hybrid-power-plant.html

It’s not just Germany that is exploring these options. In Denmark, Haldore Topose have developed a highly efficient high-temperature electrolysis-methanisation system that can convert water and CO2 into a range of synfuels/syngases.
http://biomethaneregions.cra.wallonie.be/img/download/TrainingTheTrainers_Copenhagen_HaldorTopsoe.pdf

Finland is also looking at the idea, with the focus on transport. In January 2012, the Finnish Ministry of Transport and Communications set up a task force ‘Future motive powers in transport ‘ to work out targets and plan paths for achieving them, for different motive powers in road, rail, water and air transport in 2020 and 2050. One of the motive powers considered was renewable methane, for which a sectoral report was prepared by Finnish Biogas Association and North Karelian Traffic Biogas Network Development Programme. An extended summary (31 pages) of the report ‘Roadmap to renewable methane economy’, in English, is available at www.liikennebiokaasu.fi/images/stories/pdf/Roadmap_renewable_methane_economy.pdf

It outlines a goal of 40% share for renewable methane of transport energy consumption in 2050. Progress is already being made. Two large ships (300 GWh annual methane consumption) will be taken into use: Viking Grace (a large passenger ship for Turku-Stockholm route) and UVL 10 (Finnish border patrol boat). Both of them are currently under construction in Finland by STX and they both will be using Finnish Wärtsilä dualfuel methane-diesel engines. By 2020 at least 20 vessels are expected as a result of the UN/IMO sulfur emission restrictions in the Baltic Sea.

In road transport, their target is to have 2% of vehicles methane powered in 2020, i.e. 60,000 vehicles. Also, part of non-electrified rail transport is expected to move from diesel oil to methane by 2020, but in air transport, methane use is not yet expected to have begun by 2020.

In 2020 natural gas (NG) is expected to cover 60% of transport methane use
of 2.5 TWh. Biogas (BG) and synthetic biogas (SBG) would contribute by 1 TWh
(40%). After 2020 the share of renewable methane will continuously increase
and by 2050 the use of natural gas and all other fossil fuels will end, on the basis of the groups scenario, in all transport sectors, although direct non-fossil electricity will provide some of the power.

Clearly then the renewable methane idea is moving ahead. And it’s not just a European phenomena. Canadian multi-national Hydrogenics have also developed a wind-to-gas concept, for producing CNG for vehicles, as well as grid gas, heat and power: www.hydrogenics.com

In the UK, progress has been limited: as I will be reporting in my next blog, the emphasis has instead been on natural and shale gas. But AD biogas is now being taken more seriously and there are five new government-backed R&D projects aiming to speed up the adoption of energy systems using hydrogen and fuel cell technologies, funded by the Technology Strategy Board and the DECC with £9m, in a £19m programme focused mainly on hydrogen electrolysis.
http://www.innovateuk.org/content/competition-announcements/accelerating-the-introduction-of-fuel-cells-and-hy.ashx

So far the only UK ‘air capture’ project for synfuel production using COS from the atmosphere is that being developed by Air Fuel Synthesis. This has recently begun to receive press attention after have received backing from the IMechE: http://www.imeche.org/news/archives/12-10-15/UK_engineers_create_petrol_from_air.aspx
For more see http://www.airfuelsynthesis.com

For more on wind to synfuel see:
www.youtube.comwatch?v=LqeFSxN2wAk&list=PL2E48C4FF1B7B2AB2&index=3&feature=plpp_video

Of course what matters in all of this is the energy-conversion efficiencies and costs. But good progress is being made. And the system-wide benefits of being able to store and then use otherwise wasted energy may offset the conversion costs. For more analysis see: http://pubs.rsc.org/en/content/articlelanding/2012/ra/c2ra00632d/una

For an overview see the Macogaz ‘Power to gas’ fact sheet: http://www.gasnaturally.eu/uploads/Modules/Publications/marcogaz_power2gas_fact_sheet.pdf

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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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Pipe Dreams

Construction has started on the first part of the ‘Leningrad II’ nuclear plant on the existing nuclear plant site on the outskirts of what is now St Petersburgh. The first 1170 MWe pressurised water reactor is scheduled for commissioning in October 2013 and the second a year later, at a cost of $3.0-3.7 bn per pair. Leningrad II will eventually have four new reactors.They are claimed to be super safe, with passive as well as active safety features.

As well as supplying electricity to the grid, the four new Leningrad II reactors, like the existing plant there, will also provide heat to the city- 9.17 petajoules per year of district heating. In well insulated pipes, heat losses over 10-20 km are relatively low and the demand for heat in Russia is high given the climate. Nuclear Cogeneration/Combined Heat and Power (CHP) capacity in Russia will then be supplying about 12 petajoules of heat per year, and it plans to have 5 GW of small nuclear reactors for electricity generation and district heating by 2018 at Arkhangelsk, Voronezh, Chukoyka and Severodvinsk.

So will others follow the lead and install nuclear plants in or near cites- and feed the waste heat into district heating pipes? So far most nuclear plants in the West have been located in relatively remote areas- for safety reasons and to be near sources of cooling water. But there are economic attractions in being able to use the otherwise wasted heat produced by the steam turbines. As with all steam raising power plants, whatever the fuel, the losses represents nearly 70% of the heat energy produced from the fuel, more than half of which can be reclaimed by operating in CHP mode i.e. supplying heat and well as electricity.

Even if you don’t like the idea of urban nukes (and if nothing else it could have a significant impact on property values!), there are some other interesting and possibly equally controversial ideas related to CHP/district heating. We are all used to the standard argument that putting insulation on buildings is the cheapest energy option. ‘The cheapest watt is the negawatt,’ and so on. But is it always so? Studies by CHP consultants Orchard Partners London Ltd have suggested that, in terms at least of retrofit/rehab options, it may be cheaper and lead to more carbon emission savings, to provide piped heat from urban gas-fired CHP plants, than to install insulation, especially for some hard to access high rise flats. Put simply, the argument is that it’s easier and cheaper to insulate pipes than whole buildings. They have developed a clever kerb stone pipe module that they say makes urban retro-installation easy. They claim that ‘Houses, when connected to low CO2 piped heat supply would immediately achieve the highest rating for buildings without any investment in demand side measures. The disruption to residents and traffic with the new route that has been identified will be minimal compared to the disruption replacing an unsustainable gas network under the roads and minimal for residents compared to retrofitting insulation and glazing to existing premises particularly all our pre 1950s stock.’

If you also moved to biomass, or biowaste /biogas fuelled CHP plants, then you would be more or less zero carbon- and cities have a lot of biowastes, sewage biogas for example being one of the cheapest energy sources around. At present much of it is used just for electricity production, but CHP is the logical next step. With interest in renewable heat supply growing (heating accounts for about 40% of UK energy use) some fascinating new ideas are emerging about new ways of supplying consumers’ needs- using pipes. At present we transmit electricity long distances from large power plants, with up to 10% transmission loses and even more local distribution losses. But you could have a large remote biomass fired plant, perhaps using biogas from a landfill site, which transmits heat to consumers in cities. Or a large anaerobic biogas digestor on the edge of a town or city, or even miles away, using municipal waste, and feeding biogas along a pipe to an inner city CHP plant. More likely biogas will just be added into the conventional gas main – that’s actually now been agreed as an acceptable option and some projects are underway or planned. But one way or another we may be seeing a lot more pipes in future…whether running heat or gas, the attraction over electricity being that both can be stored. We may even see the return of the classic large inner city gasometer for gas storage, along with local buffer heat stores, as are used in parts of northern Europe as a part of local district heating systems

Other renewable energy sources can also be run into heat stores- solar heat for example, allowing for variable supply to be matched to variable demand. There are even some inter-seasonal solar heat stores in operation. Once again, put simply, while no one is suggesting we don’t do both where appropriate, it’s easier to insulate a heat store than a whole house. And it’s not just solar heat, or geothermal heat, we could store. Dr Mark Barrett, senior researcher at the UCL Energy Institute, has suggested that we could use our domestic hot water cylinders as a national distributed heat store, storing excess energy from wind turbines and other large but variable electricity supplying renewables, like wave and tidal power, ready for use to reduce heat demand peaks.

Plenty of new ideas then to suit all tastes, and good news for plumbers and pipelayers! And an interesting challenge to those who think in terms of an ‘all-electric’ future.

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