Have you checked your electricity bill recently?

Does it seem rather on the high side? Would you like to reduce it?

Do you remember the Winter Storm called Diego which rushed into California in the winter of 2013-2014? When power was cut off, flights traffic snarled and cold crept in. Then the weather surged across America. This period was among the top 10 coldest on record in seven states. Freezing, icing, schools closed and even causing a number of deaths.

Chicago 2013

Cold weather happens. Costs increase. Bills mount. But what can you do – freeze?

A very few Americans have turned to Micro-CHP to try to find a cheaper form of heating. Has it worked?

And would it work for you?

But What Exactly is Micro-CHP

It’s a form of using a power source in a very efficient way – suitable for residential and small businesses.  In fact, the EIEO (energy input v energy output) is 4:1.  Most small-scale electricity systems produce under 40% efficiency. But CHP can reach 80-90% efficiency.

So, our sources of energy could last almost twice as long.

In addition, CHP is cleaner so it causes less pollution and has less effect on the climate.

And as the cost of fuel, especially fossil fuels, mounts Micro-CHP becomes an increasingly attractive proposition for the homeowner. And our supply of fossil fuels will not last for ever. How will this affect our grandchildren?

One version of micro-CHP unit

So – why are we not all using combined heat and power systems?

Many Different technologies Can Seem Confusing

At present micro-CHP is based on one of the following options:

  • Internal combustion engines
  • Stirling engines
  • Fuel cells
  • Microturbines
  • Steam engines
  • And various fuels like :
    • Natural or Propane gas
    • Biomass
    • Vegetable oils
    • Solar thermal
    • Hydro

Let’s look at some of these alternatives in turn

Engine types

Most popular are the reciprocating internal combustion engines. They operate at a fixed speed which is efficient. Yet their energy output can be varied to meet changing demands.

Natural gas is efficient, clean, lasting and takes up little space. They do not need much in the way of maintenance and can be an attractive alternative.

External combustion engines just need any very hot sources of heat. This brief video show how the Stirling engine works. Basically, the Stirling engine works by compression and expansion of air or other gas. The heat energy produced is converted to mechanical energy.

And, if you want to build your own Stirling engine (and have the tools and determination to do so) then the instructions and demonstration are here.

Who was Stirling?

Robert Stirling

In 1816 Robert Stirling and his younger brother James applied for a patent for the Stirling engine which they invented. The engine works on hot air. They called it a heat economiser but we know it today as the “Stirling engine”.

Organic Ranking

Organic Ranking requires lower temperatures and pressures. The main advantage is in the construction since it is much the same as an air-conditioning unit. This reduces cost. It is less efficient, but it could be using waste heat or a wood or gas boiler which would already be in situ.

Fuel cells

Fuel cells generate heat and electricity as a byproduct. There are no moving parts so they are quiet and need very little maintenance. Any surplus electricity can be sent to the grid. In addition, the fuel cell might be shut down at night thus prolonging its lifetime use. (in 2013 this was around 60,000 hours) and lasted around 10 years.

Japan has been leading the way and around 138,000 fuel cells (below 1 KW) were in use by the end of 2014. The usual fuel is natural gas propane gas.

 A Brief Look at the Benefits

Comparison of efficiency

The obvious benefit is the greatly increased efficiency. This means that any fuel source lasts longer and produce more power.  It might be heating for your home or producing electricity -or both. With an EIOE of 4:1 this is an impressive saving.

  • Guarding our fuel resources – with both populations and fuel prices increasing, it makes sense to guard what we have.  
  • Environment – protecting our environment is perhaps the biggest and most urgent challenge of modern times – and the efficient use of energy resources is becoming more and more vital to our survival as a race. It’s become a race in time!
  • Excess heat for the fridge – where more heat is produced than is needed, the excess can be filtered into the fridge cooling system. This may make it even more efficient.
  • Transfer loss is crushed – where heat is produced elsewhere the loss of heat in the transfer can be very great – over 40% in some instances. Insulation adds to the expense.
  • Flex  – the system is flexible and can be adapted to need. Either the primary product is heat with electricity coming as a secondary product or the other way round. In neither case is energy wasted.
  • Net metering – this is where surplus electricity goes directly to the grid, there is no waste. And it can be a big plus for the homeowner, making good economic sense.


There would seem to be very few disadvantages.

At present, the many technologies can be confusing, the choices numerous. But as research and testing are ongoing we should soon have information as to the most efficient and practical systems. So far, the tests confirm the huge benefits. Realistic targets have been set regarding durability, cost of production and installation.

One slight detraction mentioned is that the net metering will provide varying amounts of electricity to the grid. But this seems unlikely to become a big issue. No doubt, by the time enough people are using mico-CHP units to make a significant input this problem will have been solved.

Sources of energy

Natural Gas – this is not a renewable energy and it does give off carbon dioxide. But with the efficient combined heat and power systems, it is a popular first choice, easy to use and easy to set up. It is still less polluting than less heating efficient systems. Japan is leading the way here.

Biofuels – wherever heat is produced then allying it to the production of power will make it more efficient. You can find out more about biofuels here.

Solar – this might be the ultimate energy/heat system. Renewable energy efficiently used.

It is possible to produce both heat and electricity in the same concentrated photovoltaics, and Zenith Solar in Europe, claims 72% efficiency.

Schemes, Licences and Patents

You might be wondering how this will affect you? Who is making the technology available and how will it be priced.


Japan is well ahead in heating homes with micro-CHP units. Most of them use gas (natural or propane) as the energy source. Honda doesn’t just make scooters – they are also very successful in their micro-CHP units. Thousands are already in use and they have a target of 2,500,000 units for 2030.

South Korea

South Korea has an enlightened subsidy policy. Starting at 80% of the cost of domestic fuel, and running from 2012 – 2022


Nine micro Fuel Cell-CHP manufacturers are collaborating to install fuel cell micro-CHP in 12 EU member states. This is being tested and monitored over a range of conditions, climates and dwelling. The results of the analysis should be an impartial and scientifically valid source of information.

Sweden and Germany

Both Sweden and Germany have projects in hand. Powercell in Sweden has developed a unique fuel cell system to produce electricity. In Germany, the government offers big incentives.

Denmark and the Netherlands

Here they also have CHP systems in operation.


In Belgium, under the EU Horizon 2020 PACE project, over 500 fuel cell micro-CHP units have been sold to homeowners and more are on their way. And since Belgium plans to phase out the ageing nuclear energy plants in around 2025, there is an imperative need for affordable and efficient new ways of using available energy sources for heat and power. Decentralisation is becoming the preferred option – cheaper and ultimately more reliable.

In the UK

Equity Consulting released a report in 2013 which stated that the most cost-effective method to heat homes was by the use of micro-CHP.

Well, the good news for British Gas Customers is that British Gas has entered into an exclusive deal with Baxi.  Baxi state that they have “developed the most effective technology to date for the residential micro-CHP mass market”. Their Ecogen is the first wall-hanging micro-CHP unit commercially available in the UK. It has been designed with homeowners in mind and uses a Stirling engine. It makes both economic and environmental sense. (This may well reverse British gas’s reported customer losses of last year).

The United States

In the United States of America, very few people use micro-CHP units. Yet there is a huge potential for this cheaper and more efficient use of fuel. It is far more popular in Asian and Europe. Partly because of more generous subsidies – there is relatively little subsidy in America.

United States Department of Energy (DOE) has set technical targets of 1–10 kW residential combined heat and power fuel cells operating on natural gas. And the Federal government offers a 10% tax credit for smaller CHP units until 2021.

A Wisconsin company Marathon Engine Systems produces the “Ecopower”. This is a variable heat and electricity system. This gives a 70.1% waste heat recovery efficiency (and 24.4 for electricity)

And in Massachusetts, “Climate Energy” have introduced the “Freewatt” In 2007.  This system is based on a Honda MCHP engine together with a gas furnace (for warm air systems) or boiler (for hydronic or forced hot water heating systems).

The U.S. Department of Energy’s Advanced Research Project Agency funded Oregon State University’s testing of various CHP systems. The results confirmed that efficiencies reached 24’4% for electricity generation and up to 95% total efficiency. However, the most efficient units were less durable – at the moment.

And testing is still going on the immediate aim is to produce a system with 40% electrical efficiency, a 10-year life span and a cost of less than $3,000.

In conclusion

The need for energy continues to rise as the world population continues its unrelentless increase.

And fossil fuels are not endless. We need to conserve our fuel supplies and micro-CHP is both extremely efficient in providing heat for our homes. And is also affordable, cheap to run and there are even some incentives and tax credits to be found. But not being “renewable “energy there are not many subsidies in America at present. But it has the potential to pay dividends by sending surplus electricity to the grid.

This is suitable for cold climates (about 50% of US). The big task is helping homeowners understand how micro-CHP can help them heat their homes for less cost. In addition, it is one of the most effective ways we can each of us contribute to saving the environment we live in from becoming even more toxic.

At the present time, the initiative has been taken by Japan, with European countries following suit. As the different technologies produce ever better systems, so it should become routine to install and use micro-CHP in every home where heating as needed and cost is important.

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