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Tag Archives: energy storage

Energy storage – new views, Part 2

By Dave Elliott

In addition to its large-scale grid balancing role, which I looked at in my last post, energy storage may also play a role at the consumer level, with batteries allowing solar PV-using ‘prosumers’ to provide their own backup. Some see this as a possible new type of distributed storage capacity and also, more radically, as further challenging the market power of the big utilities (much of the 75GW of wind and PV in Germany is now owned by local consumers and energy co-ops), even to the point when grid systems are redundant. This may be overstated, but some more movement in that direction may be occurring in Germany and the US as batteries get cheaper.   (more…)

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Energy storage – new ideas Part 1

By Dave Elliott

Energy storage is usually seen as a very good idea – it would help cope with variable renewables. Indeed some enthusiasts now even say that cheap battery storage will make PV solar so viable at the domestic level we may not need grid power!  Or even grids!  That seems unlikely – they help to balance variable demand  with  supply  from a range of sources near and far. But one thing is clear – energy storage, large and small scale, is becoming a big issue, with many new ideas emerging.    (more…)

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Balancing variable renewables

By Dave Elliott

There is now a range of books looking at the technical and policy options available for managing the use of variable energy resources such as wind and solar energy. The pioneering text in this area was Earthscan’s “Renewable Electricity and the Grid” from 2007, edited by Godfrey Boyle , with contributions from many of the UK top experts. But the field has since expanded with, for example, a lot of new work being done in the US. (more…)

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Vehicle to grid balancing

By Dave Elliott

The vehicle to grid (V2G) debate continues, offering a way to balance variable renewables and also demand peaks, by using the batteries of electric vehicles, linked to the grid when parked at home, to store excess power during low demand periods, ready to export when demand is high and renewables low. It sounds a clever idea but in addition to economic issues (e.g. the extra costs of the home-based power uploading system) it opens up some interesting logistical issues. (more…)

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PV solar – is that all we need?

By Dave Elliott

PV solar is booming, as I noted in my last post, with over 130 GW in place globally and some see it as overtaking all other renewables, with prices falling dramatically. Indeed a new study “The Economics of Grid Defection” by the US Rocky Mountain Institute (RMI) says that PV solar and new cheap battery technology will soon mean that we won’t need power grids. (more…)

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In praise of wind power

By Dave Elliott

This year has seen yet more negativity on wind power, and proposals to cut support for on -land wind, despite this being the cheapest of the major new renewables. While overall public support for the use of wind energy remains high, in practice many new on-land projects are now opposed: two thirds of applications have been turned down in the last year. Much of this has been about visual intrusion, ‘Not In My Back Yard’ concerns relating to  treasured views and, more prosaically, possible impacts on house prices. (more…)

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Solar heating, cooling and storage

By Dave Elliott

Solar thermal and solar electricity technologies are inevitably in competition for roof space. In terms of cost/kW, PV cost more, but, at the domestic scale, heat may have lower value than electricity – electricity prices are high and heat can at present be more economically provided conventionally by natural gas. It’s a similar story when looking at an up and coming idea – solar cooling. In hot climates that is beginning to make a lot of sense. But PV electricity to run air con units is often competitive with mains power at peak cooling times, whereas using solar thermal heat to run absorption chillers is more expensive – they need much higher temperatures (well over 100 C) than for space or water heating. See Sun and Wind Energy 7-8-13.

(more…)

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Undersea energy storage

By Dave Elliott

In my previous post, I looked at airborne wind power devices, which some see as a big new energy option. One major attraction is that tapping the high speed jet streams offers access to a much more continuous and reliable energy flow than using surface level winds. It means that the problems of intermittency can be resolved without having to resort to energy storage or complex grid balancing systems. But if ‘flying wind turbines’ sound too much like ‘Blue Sky’ thinking, then, coming down to earth, or rather under the sea, there are some new large-scale storage ideas, although they too are quite exotic. They involve giant underwater compressed air storage systems.

(more…)

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Tidal power – and energy storage

By Dave Elliott

Tidal energy is developing relatively slowly, but has a significant potential. Although two large tidal barrages now exists  (with 240 MW units in France and South Korea), the emphasis is on free-standing tidal current turbines, which  harvest the horizontal flow of the tides, rather than trapping tide rises behind dams, as with barrages. So the environmental impact is likely to be much less. They can also be installed relatively quickly, one by one, so reducing project finance problems. The 6th Tidal Summit, organised by TidalToday in Nov 2012, reviewed the scene, with a key issue being the need to get costs down. DECC said they has to get to down below £100/MWh by around 2025.

(more…)

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German hopes

Germany has been pushing ahead with it bold energy transition, aiming to get 35% of its electricity from renewables by 2020, expanding in stages to 80% by 2050, with nuclear phased out by 2022. Confidence about achieving these targets seems high, indeed the 2020 target has now been raised to 40%, with offshore wind seen as playing key part. More than 20 offshore wind parks have been approved in the North Sea and three more in the Baltic, all outside the 12 nautical mile Exclusive Economic Zone (EEZ). Inside the EEZ, four wind parks have been approved in the North Sea and two in the Baltic. PV is also continuing to expand- it’s reached 30GW so far, the same as the wind capacity. However, getting coal and gas burn down is proving hard, as is cutting demand and taming the transport sector.

A recent paper by David Buchan from the Oxford Institute for Energy Studies “The Energiewende – Germany’s Gamble,” argues that “Germany is on track to meet only one of its three main targets (a one-third renewable share of electricity by 2020), that the country will fail to reach the second target (to cut energy consumption by a fifth by 2020), and that this failure will make attainment of the third goal (emission reduction) harder”. However, he says that “in a broader sense, the gamble may still come off, provided future gains in renewable technology and jobs can be achieved with lower subsidy costs. No other country possesses Germany’s combination of technical expertise from industry and of bottom-up activism from municipal companies and citizens’ cooperatives in support of low-carbon energy.” For example, private citizens own 40% of the country’s renewable energy production capacity, individually and through cooperatives. The FiT system gives many consumers a direct role in energy production via PV.

All of this makes the big energy companies uneasy- their profits are falling. They may have grudgingly accepted the nuclear exit, but some would like to see fossil fuel retained as long as possible. And indeed it makes sense to see coal and gas as bridging fuels, while renewables get up to speed, as long as emissions can be constrained. That means Carbon Capture and Storage or Combined Heat and Power linked to District Heating /, but both take time and money, and CCS is still very uncertain.

There has certainly been speculation that Germany might not make it and dire warnings about grid crises, spreading out across the EU: https://www.entsoe.eu/fileadmin/user_upload/_library/news/Briefing_paper_to_E/120416_Briefing_Paper_TO_EC_ENTSO-E_assessemnt_interconnected_system_operation_in_CCE.pdf

However so far it has managed to cope, despite the nuclear plant closures, with emissions still falling.

This might have been helped by a newly identified phenomena, the reduction in energy use below expected levels, which has been labeled the prebound effect- in contrast to the so called rebound effect- the tendency of people to use more energy net by re-spending the money they have saved form energy efficiency investment. A new study based on German data suggests that the potential fuel and CO2 savings through non-technical measures such as occupant behaviour may be higher than thought.. The research identified a recurring gulf between the quantity of energy predicted by governments for different types of housing and the amount homeowners actually use. Researchers found that the discrepancy was greatest among the least energy-efficient homes, where householders appear to be consuming far less than national energy usage standards predict. And even when comparing homes that fell into the same predicted energy bracket, it was commonplace to find cases where one house used six times as much energy as another. The study focused on data from Germany, although it then found similar patterns in several other European countries, including the UK.

‘Introducing the prebound effect: the gap between performance and actual energy consumption’, by Minna Sunikka-Blank & Ray Galvin Building Research & Information, 2012, volume 40(3), pp 260-273. http://dx.doi.org/10.1080/09613218.2012.690952

Longer term, the viability of the new German energy system will depend significantly on whether it can upgrade and balance its grid system. In addition to extra grid links, there will be a need for extra backup capacity. In 2050, by which time it is planned that renewable energy sources will supply 80% of annual gross electricity consumption, efficient gas and coal-fired power stations will have to be available to provide an estimated 60% of secured capacity – i.e. capacity available to cover demand at all times. This is the result of a study carried out by the Deutsche Energie-Agentur GmbH – the German Energy Agency (DENA): www.dena.de/studien

It says that by 2050 there would be 240 GW installed total capacity with 170 GW of renewable and 61GW of fossil fired plants. They would presumably have to be CCS linked to avoid carbon emissions, although it’s also possible that some could be biomass/biogas fired.

Certainly bioenergy has been seen as a key option in German for a range of uses, not just power production, but also a heating and transport. However, a recent German National Academy of Sciences noted that biomass production and use has a greater impact on the environment than other alternative energy sources such as photovoltaic solar energy, solar thermal energy, or wind power. http://www.leopoldina.org/en/publications/detailview/?publicationpublication=434&cHash=9daf8d722e71e30bf2901cf01ee800d1(http://www.leopoldina.org/en/publications/detailview/?publicationpublication

While that may be true for some types of biomass, transport biofuel production especially, AD biogas from wastes should be less of a problem, and, in any case, as an alternative/addition, use could be made of green gas (hydrogen and syngases) produced via electrolysis from excess wind power. In addition to helping with grid balancing, that would be less land constrained than biomass, and it would zero land using if the green gas was produced from offshore wind. Gas is also easy to store- much easier than storing electricity.
T
he development of storage capacity is of course the other big issue in Germany. To that end, 60 energy research storage projects have received financial support from the German government -which has provided €200 million for research on energy storage until 2014 to support the expansion of renewables in Germany.

Research projects are supported in the field of generating hydrogen or methane from excess wind power,; for projects aimed at connecting batteries for storage of decentralised renewable power, especially solar power, to distribution networks; projects in the area of energy system analysis, as well as thermal storage facilities. To build know-how for the transformation of the energy systems in the long-run, the programme sponsors junior research groups at five German universities which will carry out interdisciplinary research on various storage technologies. More information on the projects can be found (in German) at http://www.bmu.de/erneuerbare_energien/doc/48928.php

For regular updates on green energy developments in Germany see: http://www.germanenergyblog.de/

In parallel, on the nuclear front, Germany is to leave the 4 tonnes of plutonium that has been separated out from spent fuel it sent for reprocessing at Sellafield, in Cumbria, since it won’t be needing it back (as MOX fuel) after 2022, when all it nuclear plants close. If any MOX is needed before then it will get it from France, in a multinational swop arrangement, which avoids long distance transport. The UK closed its poorly performing MOX production plant at Sellafield, after Fukushima, and the loss of Japanese requirements for MOX. There has been talk of using some of the stored plutonium in a new reactor at Sellafied, but otherwise the UK will become the final home for it all-over 100 tonnes.

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