New Microgeneration report - what it actually says
Home fires burning won't keep the lights on
Analysis A new report on possibilities for deployment of low-carbon microgeneration machinery in British homes was published yesterday, and has scored big ink. But most of the coverage has ignored the three main messages of the report.
These are fairly simple. Firstly, according to the report, microgeneration in the UK is going absolutely nowhere without massive government backing - in the form of multibillion-pound subsidies, or regulations which would in effect place multibillion-pound levies on homeowners. Secondly, the report's authors conclude that with such massive backing microgeneration might reduce the UK's carbon emissions by as much as a few per cent; though in most scenarios the saving would be less than 1 per cent.
Finally and most importantly, however, the report notes that any success in delivery of lower-carbon national grid electricity would render most forms of microgeneration pointless. Given a halving of the carbon burden of grid 'leccy, widespread takeup of home power machinery would no longer reduce the UK's carbon emissions but actually increase them. (It's important to note that headline-worthy but marginally useful microgen kit such as rooftop wind turbines and solar cells formed only a small part of the calculations.)
The document in question is called The Growth Potential for Microgeneration in England, Wales and Scotland, and it can be downloaded in full here (big pdf). It was produced by consulting engineers Element Energy and was paid for by UK national and local government, the Micropower Council, several power companies, the Energy Saving Trust and the Renewable Energy Foundation.
It won't pay unless we all pay
The report's authors, having done their economic projections into the future, don't see any serious takeup of microgeneration without heavy government backing - to the tune of billions each year.
Subsidy schemes which achieve a widespread penetration of microgeneration have cumulative subsidy costs in the tens of billions by 2030 ... expectations of technology cost reductions appear necessary but insufficient to promote substantial consumer uptake of microgeneration. In the absence of changes to the fundamental energy economics, microgeneration technologies will require a supportive policy framework ... Even with relatively optimistic cost reduction projections up to 2050, microgeneration technologies will struggle to compete for consumers without policy support.
In particular, the most pure and righteous green home power technologies - rooftop wind turbines and solar-electric panels - require huge subsidies, several times the consumer price of electricity, to make them worth installing. Even then, most home users need loans to afford them; and the loans must be cheap or the revenue from selling high-priced subsidised power to the grid still won't cover the payments. Home windmills and solar-cell panels didn't produce enough power to seriously affect carbon emissions in any of the scenarios modelled. But there are many other kinds of microgen equipment, and it was these which seemed likeliest to be successful.
Keeping the home fires burning
Especially attractive in some scenarios are Combined Heat and Power (CHP) installations. Many Brits nowadays heat their homes and water using gas boilers, wasting a good deal of the energy they buy even with the most modern kit. Gas CHP plants cost a lot more than a combi boiler, but generate 'leccy as well as heat; wasting less overall, and so saving money over time. In future, CHP plants might use fuel cells rather than relatively ordinary options such as gas motor or Stirling-engine powered generators.
Making "cautious" assumptions about fuel-cell CHP - which isn't yet available for home use - the report's authors thought it could be brought down to the same kind of price as a combi boiler by using a within-the-realms-of-possibility subsidy regime. This meant that CHP, and particularly fuel-cell CHP, tended to dominate the future microgen projections. Like windmills or solar cells, CHP plants would sell electricity back to the grid if it wasn't immediately required. The difference is that CHP generates a lot more power.
Another crafty option for the parsimonious home owner is heat pumps, which work just like a fridge. Instead of making their insides cold and dumping heat into the kitchen, however, they make the air outside a house (or the ground beneath it) colder, and dump the heat into your radiators or your hot water system. The electricity required to drive the heat pumps is potentially much cheaper than a normal heating bill; but, again, the upfront costs are so large as to discourage most people.
Air source heat pumps are also an option
Air source heat pumps for water heating get a COP of over four. Well, the ones that use CO2 as a coolant do. They heat a tank to 90C overnight on off peak power. Millions have be sold already in Japan. Prices range from 1300UKP upwards but you've got no drilling cost as with a GSHP. The biggest ones come with a 460L tank, again at up to 90C. This means over 800L of hot water at 40 to 50C. The COP takes a big hit, but some units still produce hot water with an outside temp of -15C.
To reduce power consumption, efficiency not microgeneration is the way to go. Small scale generation is great for personal resilience though. Building passive solar houses makes the most sense for heating.
Solar power works well but not in the UK
The UK is about the worst place in the world for Solar power.
1. We need most electricity in Winter, but because we are a long way North we have short daylight hours and the sun low in the sky at that time.
2. We need least on sunny Summer days. Few houses have (nor need) air-conditioning, and a minority of workplaces.
3. We have a high average cloud cover at all times of year.
4. We have a high population density (translation, more people living under smaller areas of roof, less space for solar generation per capita). Also we have no large cheap areas of desert wasteland that could become solar farms.
5. Because of 1 and 2 the monetary value of electricity supplied to the grid in summer is lower than in winter, which further increases the payback time for UK solar.
My point in posting this is to say, do not write off solar electricity. Elsewhere in the world where it's always sunny, or where electricity demnd peaks during hot sunny summers, it is a great idea with good economics (which is why solar is popular in California and Australia, and even Dubai).
The UK government should consider building solar power stations in Southern France, Spain or Morocco, to claim the carbon credits and sell electricity into the EU electricity grid at the south. Then build some more capacity on the cross-channel interconnector and buy electricity from France. You can't say what electricity is generated where, but the effect would be a South-to-North transfer of power through Europe. (And yes, we would get back less than we put in, but it would be 100% green).
Smiling Sun face. It's that or "Mad Max".
"Of course there is the problem that twice each day it stops generating power and that does have to be covered by stations that can start and stop fairly quickly, but we have those already."
Although this is true for the Severn Barrage, this is not true for the UK as a whole. High tide comes at different times around the coast of Britain, and is completely predictable. To have a consistent supply just requires you to come up with tidal schemes spread appropriately around the coast of Britain.
You also have the options of tidal currents - there is investigation of such schemes off the north of Scotland - there are considerable currents generated through the tidal flow from the Atlantic into the North Sea. Material World on Radio 4 did a program on this topic.
If you have inconsistent demand, then you need to find mechanisms to store energy. The Dinorwen pumped storage station in Wales is one such mechanism. In Tasmania they have developed a pumped battery solution for evening out peaks and troughs from wind generation. When the battery is fully charged, you pump out the charged electrolyte, and replace it with uncharged electrolyte, storing the charged electrolyte in external tanks. When you need to draw the power off, you run the system in reverse, drawing off the discharged electrolyte and replacing with fresh.
This was described in the New Scientist: