Sunday, September 4, 2016

Community-scale Energy

Most people say small scale energy project are a good idea-  inherently better than large inflexible centralized corporately owned projects, allowing for local ownership and control. However, there can be economies of scale. Some renewable energy projects are best technically and economically at larger scale- wind turbines for example, due to the basic physics of wind energy capture and conversion.  Certainly since the power available is proportional to the square of the bade size and the cube of the wind speed, a large diameter 1MW wind turbine on a good elevated site with good wind speeds will produce far more electricity than 1000 small diameter 1kW domestic-scale micro turbines in low wind speed urban environments. Moreover, in a multi-MW wind farm with a lot of MW units, the cost of linking them to the grid and maintaining them can be shared. Similarly, for wave and tidal projects, their location is geographically defined and they will more efficient at multi-MW scale.

Some individual domestic scale energy technology can be efficient, PV solar for example, with power delivered direct from the user’s roof, but even in that case there are economies in bulk buying, installation and operational scale. Despite the need for grid links, it is cheaper and easier to buy and install a lot of units together at the same time in a large solar farm. Or possibly as part of a major roof-top deployment programme in a collective housing project.

So, although there may be exceptions, it is usually best to go for larger scale. But how large? 
Community scale projects may be a sensible compromise between scale and efficiency- small enough to be locally owned and controlled, but large enough to be efficient.  Local ownership of wind farms has proved to be a good way forward in many countries, not least in avoiding opposition to projects imposed by remote corporate owners. That is how wind took off so dramatically in Denmark, with most of the projects being locally owned. Energy co-ops are now spreading across Germany, with about 40% of German renewable energy capacity being locally owned- although some of that is domestic PV, owned by individuals.

While there is clearly a strong environmental sentiment at work, the main driver for this expansion has been economics and the availability of attractive rates from Feed-In Tariffs.
Policy changes can slow progress, although the momentum and new market that has been created means that unit costs are falling and new cheaper technology is emerging, making subsidies less vital. So it’s a success story, both in terms of capacity and the expansion of local control, to the extent that conventional energy suppliers have now lost control of much of the market. There are however some issues. The spread of distributed self-generation makes it harder to manage the overall energy system, balancing supply and demand.

Most renewables are variable, and most individual PV self-generators still top up from the grid to meet their needs when there are lulls in local solar availability and at night. So they still need grid links, which also allow them to export any excesses, and offset the costs of their system.  Some may now be installing battery storage, as an alternative, and some may even try to go off grid, but then they loose the export earnings and it maybe be hard to meet all their energy needs in this way. Arguably it makes more sense to retain grid links and import power when needed, especially since, as noted above, it can be generated by larger more efficient projects elsewhere. Grid links make it possible to use power generated at the best sites, and if suitably extended, help balance and smooth out local variations in supply across wide areas. On that basis, sticking just to autarchic local generation maybe suboptimal, whether by individuals or communities. It may require much more local capacity than otherwise needed and also more local storage, with in many case small storage systems being less efficient than large ones.  Set against that is the possibility than local grid linked storage could be seen as a form of distributed storage, taking power from the grid when available, and, along with local generation, reducing the need for large grid power exchanges at peak demand times. The need for more grids to handle variable renewables and their local impacts, is certainly an issue in some countries. That’s one reason why Greenpeace has suggested that the ratio between small/local and large/remote generation should be 70:30. That’s optimistic, depending on the location. Given the high energy use and their spatial constraints, few cities  could meet 70% of their energy needs from renewable energy generated within their boundaries: they would have to import power from rural and offshore areas. The best achieved so far, in a survey of 13 leading EU city initiatives, has been around a 7% contribution from ‘internal’ urban renewables sources: http://www.energy-cities.eu/Energy-Cities-Members-delivering

None of this means that local generation projects are a bad idea. They can play a significant role, especially at the community/municipal scale. But aiming for high levels of local self sufficiency may not be sensible or needed. Instead we need to consider the system as a whole, while opting for local generation wherever possible, so as to gain the local social benefits.  A strict interpretation of ‘local generation’ would imply near total self-sufficiency e.g. for villages and town, but in a more realistic version they could import power from projects nearby e.g. local wind farms. However, as argued above, even that seems unnecessarily restrictive- what is wrong with trading local excesses to where there is a need and at other times importing power from locations where it is best generated? 

That implies that there will still be some large scale possibly corporate led projects, run to top the system up, although in principle some of these could be municipally owned and controlled. So could the local energy distribution system, including heat supply via biomass fired CHP/ district heating networks and large heat stores, topped up with solar heat. That would still leave conventional companies supplying the energy hardware, unless new co-operative/locally owned manufacturing enterprises emerge. Or even nationalised companies, taking over the whole thing, including transmission. How far we might or should go in this ‘socialised energy economy’ direction obviously depends on your political views! But in the end it all comes down to money and power. Community groups have little of either at present, local councils not much more. So there is a way to go. However, we have seen the growth of grass roots power and local projects in Germany, and that has changed the situation. Similar initiatives may emerge in the UK: the GIFT campaign looks exciting, with, potentially, municipal involvement: www.nuclearpolicy.info/wp/wp-content/uploads/2016/04/GIFTS_initiative.pdf

Bottom-up grass roots initiatives may look weak when faced with corporate power, but with conventional politics all but frozen in many countries, they offer one of the few signs of life. See this excellent review: http://www.sciencedirect.com/science/article/pii/S1364032115013477

There is much to do at national level and policy changes are needed, but grass roots activism may help to open up new possibilities. For helpful updates on local green energy projects around the UK see: http://www.microgenscotland.org.uk

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