Small scale or domestic combined heat and power (microCHP) is seen as a saviour in helping to meet Kyoto Protocol obligations. James Hunt examines current market projections for this emerging technology, which will – within the next few years - begin to have a significant impact on the work of many electrical contractors:
CO2 emissions and the Kyoto Protocol are putting pressure on the electricity supply industry. This has been exacerbated by the gradual reduction of nuclear and older coal plants and has led to Germany, for example, needing to replace at least 40,000 MW generation1 capacity by 2020. Major blackouts in the UK, USA, Scandinavia and Italy in 2003 only intensified the problem. A possible path is distributed power. Small, decentralised, interconnected units - such as Domestic Combined Heat and Power (dCHP - now more often known as microCHP), could save some grid capacity and reduce the risk of large-scale power failure. It would also help reduce CO2 emissions and the security threat through diversity of supply, and make countries less dependent on fuel imports.
The UK Government's Energy White Paper outlines four objectives for energy policy: These are to keep energy costs low and supplies secure, to achieve reductions in greenhouse gas emissions, and to eradicate fuel poverty. The aim is to cut CO2 emissions by 60% by 2050. MicroCHP has the potential to help achieve some of these objectives.
The benefit of microCHP for owners of typical homes is that the units, which produce electrical outputs from 20.5 to 10kW (3 to 30kW thermal), could save £150-£200 a year on electricity with little or no increase in gas bills. The owner might also feel good about cutting his or her CO2 emissions by up to 25%. Installation is quite similar to a boiler and the units are already fairly unobtrusive. However, they are currently quite expensive - at least £2,000. Across Europe
In the same way that electricity supply liberalisation took place in the UK a few years ago, electricity systems in Europe are currently undergoing transformation. One development has been the emergence of distributed generation. This may lead to a more sustainable electricity supply and microCHP is a possible building block.
The recent pan-European Micromap study3 on small scale CHP covered all EU countries and Norway, plus 11 central and eastern European countries together. Micromap defined microCHP as systems capable of supplying between 10 and 100kWe and estimated a maximum CO2 reduction for Europe of 7.5m tonnes PA by 2020. This study also showed that take-up of microCHP could provide a small feed of electricity (1-3kW) into the grid, from many houses, particularly during peak hours. It could also provide new opportunities for manufacturers, energy suppliers and financiers.
The countries with the greatest potential for microCHP are the UK, France, Germany and the Netherlands as they have the greatest proportion of housing stock with gas central heating. Denmark, Finland, Sweden, Austria and Germany have the largest proportion of homes linked to heat-only district-heating schemes. For central and eastern European countries, the potential for larger dCHP ('miniCHP') is mainly in existing district heating schemes. Here, Lithuania, Latvia, Estonia, Romania and Poland have the greatest potential. New houses are likely to have very low heat demands compared with older stock.
The survey showed that 5 -12.5m microCHP systems could be installed and operating commercially in the EU by 2020. The actual number installed will depend on many factors. In addition, there is the potential to install 700, 000 units in central and eastern Europe. The Stirling engine microCHP systems producing around 1kWe of electricity will probably take the largest market share. However, there are still institutional, regulatory and financial barriers to widespread adoption and householders would need to be convinced of the benefits. Moreover, regulatory barriers - such as network access or payment for exported electricity - need to be removed.
For existing and new district heating systems, it is thought that as many as 2.2m blocks of flats or groups of dwellings throughout Europe - most in central and eastern Europe - might take up miniCHP units rated between 10 and 100kW of electricity. The resulting CO2 emission savings would be around a million tonnes per year.
However, some believe that the Micromap study may have under-estimated the European market for microCHP. 4One estimate is 40m suitable homes for microCHP resulting in a potential CO2 saving of 200m tonnes annually (or 15m tonnes saved annually on 1m installations by 2010).
In the UK:
Estimations of potential CO2 savings in the UK vary according to source. If all 12 - 13m homes in the UK capable of being converted to microCHP were so fitted, that would equate to a cut of at least 20m tonnes in CO2 emissions - nearly a quarter of the UK's total Kyoto CO2 target. In fact one survey shows a potential CO2 saving of as much as 67m tonnes annually, or perhaps more realistically, 2m tonnes saved annually by 2010 with a million homes so fitted.
A study5 for the (then) Energy Efficiency Best Practice programme, to estimate the contribution to the overall CHP target that community heating related CHP ('CH/CHP' or miniCHP) might make, has since been extended. This study also looked at dCHP. It found that for high heat demand density and smaller property sizes, community heating with CHP is, over the long term, likely to be the most effective and economic way to deliver those savings, rather than microCHP. However, over 80% of the total UK housing stock has central heating connected to the gas grid and the study concluded that microCHP technologies are, therefore, complementary to CH/CHP.
Andreas Biermann, Business Development Manager at The Energy Saving Trust, commented that the UK is probably the most advanced in Europe in terms of developing microCHP technologies and in providing market access for them. For example, Powergen plans to install 400 Stirling-engined microCHP units in the UK in 2004 as market testers. If this is deemed a success, then another 1000 units are planned for 2005. These are small numbers but bearing in mind the infancy of microCHP technology as a whole, this represents a significant start. The Energy Saving Trust believes that around 700,000 units could be in place by 2010, considering installer constraints.
In Northern Ireland, the regulatory authorities are thought to be particularly keen on microCHP takeup. The latest EU energy Directive stipulates that the market for electricity must open to include all non-domestic customers (roughly 60% by demand or an increase of around 60,000 customers) by July 2004. As part of this process, one of the Authority's many priorities in 2004/2005 will be to explore the best way of reducing CO2 emissions by joint action in the two parts of Ireland, partly through the deployment of microCHP.
Other factors:
External factors that will influence the take-up of microCHP include energy markets, the degree of competition and the regulatory framework, and electricity and fuel prices.
For microCHP to replace conventional domestic boilers on a reasonable scale, different routes to market will probably be required - such as consortia of manufacturers, installers, energy supply companies and financiers. It is possible that a significant initial route to market will be through local authorities refurbishing central heating in social housing.
It is likely that, because of the higher capital costs of installing microCHP units, compared with ordinary boilers, some financial incentives to would be needed to get the market going. The UK is again in a good position here with a framework supporting energy efficiency, called the Energy Efficiency Commitment.
McroCHP technologies:
MicroCHP is a small energy system - a direct replacement for a boiler in a hydronic heating system. It is designed for individual homes and can provide heating and/or electricity. Such units are yet to be fully developed, but should be as easy to install and service, and give at least as long a life, as conventional boilers. MicroCHP systems include an engine of some kind, with a heat recovery system, driving a generator to produce electricity. Control and exhaust systems and acoustic enclosure complete the typical microCHP package.
Technologies to power microCHP currently being investigated include fuel cells, micro gas turbines, Stirling engines and thermoelectric, thermionic and thermophotovoltaic generators. Of these, most need much further development. Fuel cells certainly work but are currently far too expensive. That leaves the venerable but sorted and reliable Stirling engine as the current main contender because this has the lowest marginal costs, shortest payback period and can be used efficiently in most flats or houses. The internal combustion engine is another possibility. Both can be natural gas fuelled.
1 Corinna Fischer, in Collaboration with Raphael Sauter - paper: 'Users as Pioneers: Transformation in the Electricity System, MicroCHP and the Role of the Users.
2 However, SBGI report - Delivering a Low Carbon Future defines microCHP as delivering up to 5kW.
3 Micromap is a pan-European study, part funded by the European Commission SAVE programme, on the potential for micro and mini combined heat and power (CHP) systems in Europe.
4 Jeremy Harrison - ER Technology - Report 'MicroCHP in Europe'.
5 BRE Energy Division, originally commissioned by Defra.
The picture shows a Baxi microCHP unit under test.
This article was originally published in European Power News magazine, published by Nexas Media Communications - a Voltimum UK Media Partner.
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