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Renew your energy: April 2010 Archives

Europe could switch to low carbon sources of electricity, with up to 100% coming from renewables by 2050, without risking energy reliability or pushing up energy bills, according to a major new study, Roadmap 2050: a practical guide to a prosperous, low-carbon Europe, developed by the European Climate Foundation (ECF) with contributions from McKinsey, KEMA, Imperial College London and Oxford Economics. It says that a transition to a low- or zero-carbon power supply based on high levels of renewable energy would have no impact on reliability, and would have little overall impact on the cost of generating electricity.

Matt Phillips, a senior associate with the ECF, said: "When the Roadmap 2050 project began it was assumed that high-renewable energy scenarios would be too unstable to provide sufficient reliability, that high-renewable scenarios would be uneconomic and more costly, and that technology breakthroughs would be required to move Europe to a zero-carbon power sector. Roadmap 2050 has found all of these assertions to be untrue." (As quoted by

ECF claimed that the widely held assumption that renewable energy is always more costly than fossil fuels is increasingly outdated, arguing that while the initial capital investment needed for low carbon energy infrastructure is more than for conventional high carbon system, the long term operating costs for low carbon energy will be lower. As a result of this, the reduction in use of increasingly expensive fuels and the gradual adoption of more efficient energy generation and using systems, it says that, although initially the GDP might be depressed very slightly, from 2020 it would rise and in the 2030 to 2050 period, the cost of energy per unit of GDP output could be about 20 to 30% lower.

The study focuses on electricity generation and use, including use in the transport and heating sectors, but says that 'should other (non-electric) decarbonisation solutions emerge for some portion of either sector, these will only make the power challenge that much more manageable'.

It looks at scenarios supplying 40% more electricity than at present by 2050, with various mixes of renewables, from 40% up to 100%, all of which it claims are technically viable. Carbon capture and storage (CCS) and nuclear are used in all its scenarios up to the 80% renewables mix, but in that scenario about half of the current level of nuclear production is replaced, and in the 100% renewable scenario all of it goes, as does CCS.

However the report notes that a successful transition to zero carbon power will depend on EU member states prioritising energy efficiency measures (it assumes a cumulative energy saving of 2% p.a.) and supporting the rapid development of a European electricity "supergrid" to help distribute and balance the green energy and manage demand.

For the 40–80% renewable scenarios there would also be a need for 190 to 270 GW of backup generation capacity to maintain the reliability of the electricity system, but ECF notes that 120 GW of that already exists. For new backup it looks to more gas-fired plants, biomass/biogas fired plants, and hydrogen-fueled plants, potentially in combination with hydrogen production for fuel cells.

In the case of the 100% renewables scenario, 15% of the energy would be imported via a supergrid link from Concentrating Solar Power (CSP) plants in North Africa, and 5% is also obtained from enhanced geothermal around the EU. But given the wider footprint and supergrid links, backup requirements in this scenario were reduced to 215 GW. However, the extra cost was put at 5–10% more than the 60% renewables option.

A study by consultants PriceWaterhouseCoopers, in collaboration with researchers from the Potsdam Institute for Climate Impact Research (PIK), the International Institute for Applied Systems Analysis (IIASA) and the European Climate Forum (ECF), has also claimed that Europe and North Africa could be powered exclusively by renewable electricity by 2050, if this is supported by a single European power market, linked with a similar market in North Africa.

Like ECF above, they also look to a cross-national power system, the proposed Super Smart Grid, to allow for load and demand management, and to integrate in green energy. They too see power coming from concentrating solar projects in the deserts of North Africa, and also in southern Europe, as well as from the hydro capability of Scandinavia and the European alps, onshore wind farms and offshore wind farms in the Baltic and North Sea, plus increasingly tidal and wave power and biomass generation across Europe.

Like the ECF study, they concludes that 'the most recent economic models show that the short term cost of transforming the power system may not be as large as previously thought', and that overall reliability would not be compromised. And they add that the development of North African resources 'could pay big dividends in terms of regional development, sustainability and security.'

An even more radical conclusion was reached in the study by the European Renewable Energy Council (EREC), Rethinking 2050, which claims that the EU could not only meet up to 100% of its electricity demand from renewables by 2050, but also all of its heating/cooling and transport fuel needs.

Like the studies above, it assumes a major commitment to energy saving – overall energy demand it says can be reduced by 30% against the consumption assumption for 2050. And there would be a parallel rapid rise in renewables, with an average annual growth rate of renewable electricity capacity of 14% between 2007 and 2020, and then an even more rapid expansion of some options. Between 2020 and 2030, geothermal electricity is predicted to see an average annual growth rate of installed capacity of about 44%, followed by ocean energy with about 24% and CSP with about 19%. This is closely followed by 16% for PV, 6% for wind, 2% for hydropower and biomass with about 2%. By 2030, total installed renewable capacity amounts to 965.2 GW, dominated in absolute terms by PV, wind and hydropower. Between 2020 and 2030, total installed renewable capacity would increase by about 46% with an average annual growth rate of 8.5%. And after 2030, expansion continues leading to almost 2,000 GW of installed capacity by 2050.

Some even more radical scenarios have emerged, suggesting that we could move even more rapidly. For example, the German Energy Watch Group claims that (non hydro) renewables could supply 62% of global electricity, and 16% to global final heat demand, by 2030.

And last November, Prof. Mark Jacobson and Mark Delucchi from Stanford University in the US published a very ambitious scenario in Scientific American, which suggested that up to 100% of global energy could be obtained from renewables by 2030, with electricity also meeting heating and transport needs.

Although they claimed that 100% was technically feasible by 2030, recognising that there were sunk costs in existing systems, in their conclusion they pulled back a bit and said that, in practice, 'with sensible policies', nations could set a goal of generating 25% of their new energy supply from renewables 'in 10 to 15 years and almost 100% of new supply in 20 to 30 years'. But they insisted that 'with extremely aggressive policies, all existing fossil-fuel capacity could theoretically be retired and replaced in the same period' although, 'with more modest and likely policies full replacement may take 40 to 50 years'.

Delucchi is scheduled to report on this analysis at a conference on long range scenarios being organised jointly by the UK Energy Research Centre and Claverton Energy Group on 21 May at University College London. Other contributors will include Dr Mark Barrett from UCL, who has developed a detailed 100% UK Renewables scenario. Visit

Conference details:

Shortly the Centre for Alternative Technology in Wales is expected to publish its revised and updated Zero Carbon Britain scenario for up to 2030. That too is likely to be very radical. Perhaps somewhat less so, the Department of Energy and Climate Change meanwhile is still working on its own 2050 Road Map. Some brief interim conclusions have emerged, but the full thing is still being developed. I'll be reporting on that in my next blog. Clearly we are not short of scenarios!

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Beyond baseload

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We are always told that it's vital to have 'baseload' – that is 'always available' generation capacity – to meet minimum energy demand. Otherwise the lights would go out! Baseload used to be provided mainly by coal plants, these days it's also nuclear. Indeed, on summers nights when UK demand drops to 20GW or so, it can mostly be nuclear, plus whatever we are getting from our ~6GW of wind and other renewables. But when wind expands (to maybe 40GW!) and nuclear also expands (to say 20GW), then there will be conflicts over which to turn off ('curtail'), during those periods, especially if there is also, say, 10GW of tidal on the grid. In which case the concept of baseload starts to look unhelpful – the problem being a potential surplus of electricity, not a shortfall.

To avoid 'curtailment' problems, we might store some of the excess power or export it to other countries on a supergrid system. That might also help us to balance the variations in output from wind and other renewables – in effect we export excess and then re-import it later when and if there is shortfall. It get stored in, say, large hydro reservoirs in Norway or Sweden (as Denmark does with its excess wind output), although it's really just 'virtual' storage. We don't get the same electrons back! But for this to be possible we need the grid links.

The same message emerges from recent US National Renewable Energy Laboratory studies of wind curtailment, though their problem is a bit different. A 2009 NREL study concludes that, so far, congestion on the transmission grid, caused mainly by inadequate transmission capacity, is the primary cause of nearly all US wind curtailment.

NREL says that wind curtailment has been occurring frequently in regions ranging from Texas to the Midwest to California. For example it notes that at one point in 2004 nearly 14% of wind generation MWh had to be curtailed in Minnesota, though this fell to under 5% subsequently. It notes that, curtailment has also become a significant problem in Spain, Germany, and the Canadian province of Alberta – up to 60% in Germany in some cases, while in Spain, NREL notes 'the amount of wind power curtailed as part of the congestion management program has increased steadily over the past two years' . This is a terrible waste of potential green power…

NREL says that building additional transmission capacity is the most effective way to address wind curtailment, a point also made in its 2010 'EWITS' study of eastern US options – which concluded that wind could replace coal and natural gas for 20–30% of the electricity used in the eastern two-thirds of the US by 2024. That would involve 225–330GW of wind capacity, and an expensive revamp of the power grid. However, like the earlier NREL study, it says that, with an improved grid, especially with long distance HVDC transmission allowing for balancing across the country, the amount of wasted wind energy, and the need for back-up, would decline.

The 2009 study also discusses other possible measures for reducing wind curtailment, including greater dynamic scheduling of power flows between neighbouring regions. That's moving in the direction of 'smart grids' and possibly on to dynamic load management – adjusting demand in line with supply. It's already common to reschedule some large load to meet shortfalls in supply – some supply contracts specify interruption options – and reduce prices accordingly. But more sophisticated smart grid systems may have fully interactive load control – switching off some loads temporarily when supply is weak. The classical example is domestic (and retail) freezers, which can happily coast for several hours without power or damage to food stocks.

What we are seeing is a move beyond simple real-time 'baseload' thinking and on to balancing supply and demand dynamically, over time. This can involve more than just rescheduling loads or shifting electricity across regions via supergirds, and more than just storing electricity virtually. It can mean shifting to storing some of the electrical energy as heat – heat is much easier to store (e.g. in molten salt heat stores, than electricity). And local heat stores can be topped up with heat from solar and other renewable sources. Most of this heat would be used to meet heating needs directly, but some could be converted back to electricity, for example in steam turbine units, as is planned for the large Concentrating Solar Power plants being built in North Africa – to allow them to carry on generating power from stored solar energy overnight.

A parallel option is conversion of electricity to hydrogen gas via electrolysis, for later use as a fuel, for vehicles, or for heating, or for electricity (and heat) generation in a fuel cell. The efficiency losses from some of these conversion processes may limit how much of this we can use cost-effectively, but we need to start thinking about new optimisation approaches which go beyond simple real-time power links. Neil Crumpton's scenario tries to do that: see my earlier report.

It's definitely a challenge to conventional thinking. As Eric Martinot puts it in Renewable World (Green Books): "The radical concept that 'load follows supply' on a power grid (i.e. the loads know about the supply situation and adjust themselves as supply changes) contrasts with the conventional concept of 'supply follows load' that has dominated power systems for the past hundred years. Storage load represents a variable-demand component of the power system that can adjust itself, automatically within pre-established parameters, according to prevailing supply conditions, for example from renewable power."

Energy storage is of course expensive, which is the main reason why we don't have much of it at present. But as we move to a new more interactive energy supply and demand system, then the value of stored energy will increase. You could think of it as 'virtual' baseload. But it's more flexible than that – and flexibility seem likely to be a key requirement in future.

For more on renewable energy and allied smart energy developments, visit Renew.

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Will installing large numbers of wind turbines have an impact on the environment – not just visual intrusion, but actual measurable effects on the atmosphere and climate? After all if you are taking many giga watts of power out won't that slow the winds down? And have other effects?

Well the first thing to realise is that wind turbines only extract very small amounts of the energy in the wind front – which after all can be a mass of air hundreds of miles wide and several miles high. That said there can be local wind shadow effects. Indeed in medieval times there were regular disputes about blocking wind access to corn grinding windmills. But in macro terms the extraction issue would seem to be negligible.

What about more subtle impacts? In a paper in Atmos. Chem. Phys. 10 2053–2061, 2010, entitled "Potential climatic impacts and reliability of very large-scale wind farms" C. Wang and R. G. Prinn from the Center for Global Change Science and Joint Program of the Science and Policy of Global Change, Massachusetts Institute of Technology, argue that the widespread use of wind energy could lead to temperature changes. They used a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. They claim that 'Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1 °C over land installations. In contrast, surface cooling exceeding 1 °C is computed over ocean installations,' but they add ' the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study'.

They go on 'Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur,' and explain that 'these results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds'. They also say: 'These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation.'

Well yes, they do seem to have adopted a rather simplified 'top down' model – assuming increased drag from increased surface roughness averaged out over entire coarse-resolved grid cells, rather than looking at the impacts of individual wind turbines. An earlier 'bottom up' study 'Investigating the Effect of Large Wind Farms on Energy in the Atmosphere', in Energies 2009, 2, 816-838 by Magdalena R.V. Sta. Maria and Mark Z. Jacobson of the Atmosphere/Energy Program, Civil and Environmental Engineering Department, Stanford University, used Blade Element Momentum theory, to calculates forces on individual turbine blades. It claimed that 'Should wind supply the world's energy needs, this parameterization estimates energy loss in the lowest 1 km of the atmosphere to be ~0.007%', which it said was 'an order of magnitude smaller than atmospheric energy loss from aerosol pollution and urbanization, and orders of magnitude less than the energy added to the atmosphere from doubling CO2.'

It added that, although there may be small moisture content changes and other minor effects, 'the net heat added to the environment due to wind dissipation is much less than that added by thermal plants that the turbines displace'.

Pretty clearly then we have a disagreement: especially given that Wang and Prinn say '1 degree from a 10% wind contribution': would that means 10 degrees for the 100% total energy contribution looked at by Maria and Jacobson?

Underlying this conflict are pro and anti wind postures, with Maria and Jacobson obviously very much in favour, while Wang and Prinn's paper adds in for good measure some familiar negative comments about the intermittency of wind power and the need for backup generation capacity, very long distance power transmission lines, and onsite energy storage.

Wind power does have its problems, but they seem to scraping the bottom of the barrel by trying to talk up miniscule temperature effects.

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