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.
By Dave Elliott
Imperial College has looked at Heat System Decarbonisation (PDF) in the UK in a new report. Provocatively it says solar and biomass heat can only play limited roles for direct space heating, and focuses mainly on three other low carbon system options: a shift to using hydrogen in the gas grid, the use of decarbonized electricity to run heat pumps, and the creation of local heat networks.
By Dave Elliott
A new report ‘Policy for Heat: Transforming the System’, from Carbon Connect, follows a cross-party inquiry chaired by Shadow Energy Minister, Jonathan Reynolds MP, and Conservative MP Rebecca Pow. It argues for the better development and greater integration of policy on low carbon heat, energy efficiency and new-build homes. It notes some big problems with current programmes, not helped by the scrapping of the Green Deal and the Zero Carbon Homes policy. (more…)
by Dave Elliott
By their nature, wind and solar energy are variable and there is likely to be excess electricity generated from using these resources at times, and shortages at other times. It is hard to store electricity directly, but the energy can be converted into more easily storable forms.
One of the big hopes for the future is the ‘wind to gas’ idea- using excess wind-derived electricity to produce hydrogen gas by electrolysis for storage and then use, when there is a lull in the wind and high demand, to generate power in a fuel cell or gas turbine. Alternatively, the hydrogen, or methane derived from it (and from captured CO2), can be fed into the gas grid to replace fossil gas. For once the label ‘game changer’ might even be right- perhaps the key to a balanced energy future, compensating for variable inputs from renewables. It seems like an idea whose time has come: www.aspo2012.at/wp-content/uploads/2012/06/Pengg_aspo2012.pdf
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.
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.
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:
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