Combined Heat and Power (CHP)
Combined Heat and Power (CHP) or cogeneration is the simultaneous production of two types of energy – heat and electricity. Normally fuelled by natural gas a CHP unit is more efficient and thus provides not only cost savings but also provides a greener, lower carbon solution than conventional electricity from your utility provider and heat from a boiler.
The key parts of a CHP are an internal combustion engine, often referred to as a reciprocating engine and an electric generator. The principals of a CHP are relatively easy to understand - natural gas fuels a gas-fired engine which spins a generator to produce electricity while the heat is generated by the engine as it works.
The electricity generated is used by your building, with any additional electricity needed simply being delivered as normal from the grid. The heat is captured using heat exchangers not only from the engine’s water cooling circuit but also from the exhaust gases and even the engine oil itself. This heat is then connected to your existing heating system to supply space heating, heat domestic hot water or to provide heat for swimming pools and spas.
Efficiency of CHP Systems
Combined heat and power systems use fuel very efficiently. A CHP system provides electricity and heat at a combined efficiency approaching 90%. This is a significant improvement over the combination of the 30 to 35% efficiency of conventional electricity generated by a power station and a conventional boiler with a seasonal efficiency of, on average, 60% to 65%.
Conventional power stations are in effect CHP systems as they also produce electricity and heat. Unfortunately power stations are inherently inefficient as most of the heat is wasted in cooling towers and chimneys. In addition, as power stations are located away from where the electricity is used further energy is lost simply transmitting the electricity over high voltage cables and across pylons to our cities and towns.
Although modern condensing boiler technology has dramatically improved seasonal boiler efficiency we must remember that most boilers are not modern condensing technology. For this reason their efficiency is far lower, typically round 65%.
The key to the success of CHP is a properly applied solution that makes use of the heat year round. Such a CHP solution recovers nearly all of the heat it produces and uses it on-site. This avoids the need to dump heat while generating electricity and maximizes the efficiency of the solution.
CHP-produced energy is more cost effective than the combined energies from the electricity grid and local boilers.
Benefits of Combined Heat and Power
Because of the higher efficiency of the system, CHP solutions provide considerable energy, environmental and economic benefits.
CHP consumes natural gas, a fuel that is both less expensive per kWh of energy consumed and contains less carbon. This means that CHP energy is both cleaner and less expensive than the conventional alternatives. CHP solutions also reduce the demand on the national grid, increase overall energy efficiency and can also help protect your buildings from power cuts.
Lower Carbon and Supported by Government
CHP is recognised throughout Europe as an efficient and low carbon technology. Here in the UK successive Governments have sought to support CHP and encourage its take up.
Currently good quality CHP enjoys that meets the criteria of the CHPQA enjoys exemption from the Climate Change Levy. This increases the savings potential of CHP, reduces payback times and increases the overall return on investment.
Additionally, those organisations participating in the CRC Energy Efficiency scheme can reduce their carbon footprint using CHP and as a result pay less to Government for the CRC allowances they must buy each year.
Consultations later this year are also expected to offer new support for CHP as the UK seeks to reduce its emissions yet further over coming years.
Combined Heat and Power Installation and Operation
Although a proven and efficient technical solution, installing a CHP unit requires both capital and experience. Installation requires skilled and experienced system engineering, project management, electrical and mechanical design and implementation.
Once installed the system must run day in, day out for hour after hour. This need for continuous operation requires expert planned maintenance to optimize performance.
For many businesses finding the cash and the expertise to install and operate a CHP system presents a challenge. In most cases, EuroSite Power's On-Site Utility System™ is the best option.
What buildings are suitable for CHP?
The following qualifying criteria can help determine whether or not your building is a good application for CHP.
- Natural gas is available on-site
- Domestic hot water is supplied from a central boiler plant and not by point of use heaters
- Space heating is supplied from a central boiler plant supplying either low temperature or medium temperature hot water to radiators, underfloor heating, fan convectors or fan coils.
- The property has a requirement for heat all year round e.g. contains a swimming pool or spa, domestic hot water (hotel or care home with c.120 rooms/units or more)