MicroCHP

The extremely high efficiency of Micro CHP systems is dramatically superseeding ordinary energy technology.

By comparison, traditional electricity production has an efficiency of only 30 - 40%. Thus, the EC Power Combined Heat and Power solution can reduce energy bills by 40 - 60%, or increase efficiency by more than 100% - a considerable improvement.

Furthermore, the EC Power solution will reduce future investments in the energy infrastructure. By decentralising energy production, the need for new, regional transmission systems for heating and power will be diminished and transmission losses, a substantial cost factor in any centralised energy supply system, will be greatly reduced or become non-existent.

Installation is simple and fast, occupying only minimal space. The largest system only requires 2 square meters (18 square feet) of floorspace, even though it is capable of producing 17 kilowatts of electricity and 24 kilowatts of heat.

The system arrives pre-engineered and fully automated. It consists of a prime mover cabinet (comprising an engine, generator and exhaust heat exchanger), a heat storage system and an advanced computer management package.

Accessories such as heat pumps and/or gas/oil fired boilers can be added to become an integral part of the complete control system.

The MicroCHP solution is an open platform that can be implemented into any new or existing installation.

In the majority of energy applications, energy is required in multiple forms. These energy forms typically include some combination of: heating, ventilation, and air conditioning, mechanical energy and electric power. Often, these additional forms of energy are produced by a heat engine, running on a source of high-temperature heat. A heat engine can never have perfect efficiency, according to the second law of thermodynamics, therefore a heat engine will always produce a surplus of low-temperature heat. This is commonly referred to as "waste heat" or "secondary heat", or "low-grade heat". This heat is useful for the majority of heating applications, however, it is usually not considered practical to transport heat energy over long distances, unlike electricity or fuel energy. By transporting fuel, however, the "waste heat" is essentially being transported along with the fuel, before the waste heat is actually produced.

To make efficient use of energy, the "waste heat" must be used purposefully. Since it is practical to transport electricity, but impractical to transport waste heat, an energy efficient system must generate electricity only at locations where the waste heat can be put to good use. In a central power plant, the supply of "waste heat" often exceeds the demand, so the waste heat has very little economic value. Then the waste heat is typically dissipated in a cooling tower without ever being used purposefully. One way to make better use of the "waste heat", is to consume the primary energy source on-site, and thus generate energy in all of the required forms, at the point-of-use. This is known as a combined heat and power (CHP) system, or "cogeneration".

The majority of cogeneration systems use natural gas for fuel, because natural gas burns easily and cleanly, it used to be inexpensive, it is available in most areas and is easily transported through pipelines, which already exist for many homes. Natural gas is suitable for internal combustion engines, such as Otto engine and gas turbine systems, because it burns without producing ash, soot or tar. Gas turbines are used in many small systems due to their high efficiency, small size, clean combustion, durability and low maintenance requirements. Gas turbines designed with foil bearings and air-cooling, operate without lubricating oil or coolants. The waste heat of gas turbines is mostly in the exhaust, whereas the waste heat of reciprocating internal combustion engines, is split between the exhaust and cooling system.

The future of combined heat and power, particularly for homes and small businesses, will continue to be affected by the price of fuel, including natural gas. As fuel prices continue to climb, this will make the economics more favourable for energy conservation measures, and more efficient energy use, including CHP and micro-CHP.

There are many types of fuels and sources of heat that may be considered for micro-CHP. The properties of these sources vary in terms of system cost, heat cost, environmental effects, convenience, ease of transportation and storage, system maintenance, and system life.

Some of the heat sources and fuels that are being considered for use with micro-CHP include: biomass, woodgas, solar thermal, and natural gas, as well as multi-fuel systems. (Nuclear power is hazardous at small scales, due to radiation risks, so it is generally not viable for micro-CHP.) The energy sources with the lowest emissions of particulates and net-carbon dioxide, include solar power, biomass (with two-stage gasification), and natural gas.

The typical UK house is thought to take about 3,300 kWh of electricity a year. (This conventional assumption is used in all advertising and in product comparisons. It is out-of-date and 3,700 would be a better figure.) If this demand was exactly constant, it would mean that the CHP plant would need to deliver 377 watts of electricity all the time, and provide a similar amount of hot water heat. The annual savings from using a typical CHP plant, above and beyond those installing a good condensing boiler are still quite large, though not as great as if the CHP cell worked constantly at 1 kW.

* £249 in reduced electricity charges, net of a smaller increase in gas bills
* 0.55 tonnes of CO2

I want to stress that the savings that I estimate also assume absolutely constant electricity demand and a perfect match between the amount of heat provided and household needs for hot water. Of course, real households have rapidly and erratically varying electricity needs and more consistent, but still highly unpredictable, hot water needs.

To have maximum value to the householder, the electricity demand of the home should be a constant 1 kW. This would enable the CHP plant to deliver a high and consistent efficiency and maximise the savings.

When it was generating 1 kW of electricity, the CHP plant would also be delivering approximately 1 kW of heat to the hot water tank. About 0.4 kW would be wasted, partly in the form of unused heat and partly in electricity used to drive the CHP plant itself.