How plausible is a scenario of abundant use of distributed microgeneration for electricity and heating? Microgeneration -- the use of small-scale power generation sources like photovoltaics and wind micro-turbines -- has tremendous potential as a way of improving energy network reliability and increasing the use of clean, renewable power. Much of the discussion of the components necessary for both energy generation and a distributed network focuses on the plausibility and utility of the technology itself. But once we accept that these technologies are at least potentially viable, how then can we model market acceptance, uptake, and impact?
The UK's Department of Trade and Industry authorized the Energy Savings Trust, a non-profit company set up by the UK government in the wake of the 1992 Rio Earth Summit to promote energy efficiency and to combat climate change, to perform an in-depth examination of the potential of microgeneration, and to determine what would be required to make various technologies successful in terms of both consumer demand and climate/energy efficiency.
The study's final report has now been published (PDF). Even if you don't live in the UK, if you have any interest in microgeneration or the role of distributed power in fighting climate disruption, you need to download and read through this paper. It's relatively lengthy -- running a bit over 200 pages -- but is presented as a slide deck, and is easily skimmed. Its findings are fascinating (at least to me).
Potential for Microgeneration: Study and Analysis covers small-scale photovoltaics, wind turbines, microhydro, "active solar water heating," ground source heat pumps, bio-energy, combined heat-power (CHP) systems, and fuel cells, and studies their impact on energy consumption, climate emissions and the evolution of the power grid out to 2050. They look at variations such as Stirling engine CHP and a variety of biomass heating systems, and map out the cost-competitiveness for each technology under a mix of scenarios.
Much of the report examines the perceived barriers to uptake for the various technologies, and what it might take to change those barriers -- if change is possible. One of the aspects of the report that I found most appealing is the combination of a willingness to entertain a wide variety of alternative and renewable energy technologies without falling victim to the "if it's nifty, everyone will like it" mindset that alt energy proponents often have. This is, in many respects, a conservative take on the prospects of renewable energy microgeneration; it counts on few if any radical technological breakthroughs, and few real changes to the structural barriers to uptake (such as the cost of baseline centralized power).
Although the details are relevant to the UK experience alone, the broader conclusions are useful across the industrialized world. The two main non-technological forces that can determine the success or failure of different microgeneration options are regulation (here meaning both subsidies and building codes) and "energy export equivalence" -- that is, the question of whether power companies pay the same amount for distributed-generation power from consumers that they charge for centralized power to consumers. In the medium-term, the smart application of regulations, including the removal of subsidies when the technologies get a firm footing in the market, and a cost equivalence of both "import" and "export" of power make a greater difference to the use of microgeneration than any other variable, including the effectiveness of the technologies themselves.
The CO2 impact of microgeneration is significant, but not spectacular, amounting to about 15% of non-commercial CO2 production (it's unclear whether this includes transportation). Overall, the Energy Savings Trust projects that around 25% of energy demand will be met by microgeneration.
As interesting as the report is, it's missing a few important elements. Outside of the report's scope, for example, is the impact of "zero-energy development" schemes on overall energy demand, and how distributed microgeneration would fit with broader use of ZED designs. Similarly, there's no consideration of the impact of significant breakthroughs in renewable energy technologies, most notably developments that greatly lower the cost or increase the utility of photovoltaics. Perhaps most importantly -- as it is within the scope of the report and is directly relevant to its conclusions -- there's no discussion of serious increases in energy costs arising from "peak oil" and similar conditions. (Even though petroleum isn't widely used for electricity generation and heating, a serious decline in its availability has a spin-off effect on other fuels like natural gas and coal, which may get called into service as petroleum replacements.)
In spite of these missing elements, Potential for Microgeneration: Study and Analysis is easily the most detailed report I've seen on the nuts and bolts of what's required to make distributed power generation a reality. The conclusion is clear: shifting to a distributed microgeneration model won't be easy, but it's very possible. I'd like to see similar reports from across the industrialized world.
