Tuesday, March 1, 2016
The right mix: in praise of grid links
A new Greenpeace report on getting to 100% renewables globally by 2050 revisits the familiar issue of scale: what’s the right mix of large-scale centralised and small-scale local projects? It suggests a 70:30 ratio, arguing for mostly decentralised power (i.e prosumer domestic PV projects and community scale distributed generation), although it admits this will require more local capacity than if more imports from more efficient larger projects elsewhere were allowed. It does assume some are (e.g. from offshore wind and CSP), but not much: it’s keen of to get the benefits of local control and ownership, and it also worries about long distance transmission energy losses and grid cable visual impacts.
The issue of local control is an important one, but over-reliance on small-scale local systems comes at a cost: not all resources are even distributed. Surely it is foolish to limit the use of efficient off-shore wind, wave and tidal farms and CSP in desert areas? And surely, even if they are more autonomous than now, there is nothing inherently wrong with trading surpluses between communities? It depends on how the trade is done. Technically, long distance transmission losses can be low (2%/1000km) and grid impacts can be avoided (it’s easier to bury HVDV than AC grids), or reduced by doubling up or replacing existing lines. But the other issue is that Greenpeace want to avoid most biomass use (not biogas from wastes, but all biomass imports). That means more electricity has to be produced for heating and transport. A report from the German Federal Environment Agency, UBA, says that, in this situation, even with a lot of Power to Gas/ Liquid conversion of excess renewable electricity (as Greenpeace also suggests), Germany will have to import a lot of green electricity from abroad, similar in scale (but not type) to their fuel import level now: with biomass limited, there wouldn’t be enough from local sources. www.umweltbundesamt.de/publikationen/germany-2050-a-greenhouse-gas-neutral-country
It does sound like you can’t avoid some long distance transmission, and of course if you have it, although it opens the door to centralised corporate power, it helps with balancing local variations in supply and demand across wide areas, with differing resource availability. So a 50:50 local/import ratio might make more sense, depending on location. Or, of course, if you want more local power, again depending on location, you could go for local biomass production and use. Forget about importing wood pellets, and probably most biofuels for vehicles, but, in addition to AD of local farm, food and home biomass wastes, surely some types of fast growing energy crops for power and heat, like short rotation coppicing, can be acceptable in rural areas, without land use or biodiversity conflicts?
Greenpeace is also nervous about hydro, with large projects being seen as invasive, despite the fact that hydro reservoirs can be used to help balance variable renewables, via pumped storage. Some countries wont have much hydro capacity, but if they have grid links to other countries with hydro projects they can be used for pumped storage. That’s already done by Denmark, using Norwegian hydro to store its excess wind derived electricity, for later re-import when Danish wind is low and demand high. Once again it shows how useful grid links can be, as in fact an earlier Greenpeace study of EU options had argued: www.energynautics.com/news/#GP_EU
The new Greenpeace report is very good, arguing convincingly that, with proper attention to energy saving, supplying 100% of energy globally is possible using just renewables, and would not cost more net, given the savings on the use of fossil fuel. But the issues touched on above are real ones. Big hydro and large-scale biomass use do both open up many environmental issues, so it may be that they have to be kept in check. Or at least be subject to careful regulation. Similarly, there are political issues related to trading energy, as we are well aware of with fossil fuel and the power that has given to global energy corporations. We don't want to replicate that with renewables. Surely we can come up with more democratic ways to manage energy systems, even large systems, and avoid rip-off trade relationships? That's something that is currently a central political issue anyway, with, in the UK, much talk of taming the Big 6 power companies. It won’t be easy. Especially as we also need to reconfigure the energy system overall.
However, as part of doing that, we have to face the issues raised above. It will vary by country. But in general, trying to duck these issues, by avoiding big hydro and biomass, and limiting trade/transmission, would add costs and, arguably, make it harder to develop a viable system. We need to decide what sort of system we need, how to link it up effectively and equitably, what impacts we can accept and what trade-offs we want to make between overall technical efficiency and community scale. Quite an agenda! www.greenpeace.org/international/Global/international/publications/climate/2015/Energy-Revolution-2015-Full.pdf
An incremental approach is to just focus of local energy and hope that it can expand: building up from beneath. The rise of ‘prosumers’ and local energy co-ops in Germany suggests that this might be possible, although it has occurred mainly due to favourable market frameworks provided by the government – and that may change. Indeed it already is, with FiTs being phased out, there and elsewhere. In the UK, the new Shadow Energy Secretary, Lisa Nandy, has said Labour wants to ‘democratise rather than nationalise’ the energy system. She told delegates at last years Labour party conference that every community in the country should be able to own their own clean energy power station. http://ow.ly/SPLVa That’s fine as far as it goes, but it probably wont be enough to completely change the system. The Thousand Flowers UK scenario produced last year by the transition consortium looked to local councils playing a major role, and focused heavily on community-scale biomass-fired CHP, and heat as well as power production. That might reduce some of the power transmission issues: it would certainly be hard for the power grid to cope with the electricity needed to meet all the UK’s heat needs. But would there be enough biomass for that? And if so, would we be happy for it to be used? The issues wont go away!
All this and much more is discussed in my new IoP book Balancing Green Power out later this year.