Onsite cogeneration of electricity with heat reclaim by Combined Heat and Power, or CHP units, is one of the most effective ways of reducing costs by simultaneously powering and heating a building from a single gas-powered engine.
As gas supply remains on a par with or slightly cheaper than grid-supplied electricity, and because Combined Heat and Power units secure ‘free / waste heat’ as part of that power generation process less gas overall is required for the heating of the building. So there are two opportunities to reduce operational costs.
The micro-CHP form factor that we deploy in the TOTEM series of CHP units was originally conceived and brought to market in the late 1970s. Subsequently, the design has evolved and improved, incorporating the latest engineering practices and expertise from the automotive industry to ensure the design is optimised to meet the real-world needs of a building project.
The TOTEM m-CHP internal combustion engine is a product of the automotive expertise of Fiat Chrysler Automobiles’ (FCA). The continuous development over 50 years, gives the current gas-driven 1.4L Fiat Fire engine an astounding reliability rate of 99.6% over 100,000 units per year.
The Engine Control Unit (ECU), high-efficiency catalytic converter and fine-tuning for the engine’s stationary parameters is provided by Magneti Marelli, a name which will be familiar to fans of Formula One racing. It is the ECU and catalytic converter that which deliver TOTEM’s ultra-low NOₓ and CO emissions. This is particularly important for urban building projects where NOₓ (a combination of NO and NO2) is seen increasingly as a major factor in air pollution which can be extremely harmful to people. As Combined Heat and Power localises energy production, it is critical that the use of the technology addresses and significantly reduces NOₓ generation. NOₓ emissions from a TOTEM unit are less than 40 mg/kWh of electricity output, but once you take the heat output into account, which is considered a waste product, TOTEM becomes effectively NOₓ free.
TOTEM achieves ultra-low emissions rates – that are less than 10% of most micro-cogeneration units available on the market – through the close manufacturing relationships, of Fiat, Magneti Marelli, Asja and Adveco which has driven the adoption of micro-CHP in the UK through unique technology and service support. For this work, Adveco has been recently awarded a Frost & Sullivan Technology Innovation Leadership Award for developing commercial micro-CHP in Europe.
TOTEM stands out with its complete, highly compact system in a box configuration, a design-driven by the decision to directly couple the engine to the generator, which is capable of delivering electrical outputs from 10 to 50 kW, and then closely integrate the other components, especially the condensing heat exchangers.
A building’s central heating water is heated directly in two stainless steel shell and tube heat exchangers and a water to water stainless steel plate heat exchanger transferring heat from the engine coolant (used to cool the engine, oil, and generator water jacket) and from the first stage exhaust. By reclaiming heat from every available source, TOTEM micro CHP units achieve a thermal efficiency of 65% or higher depending on the return water temperature. The TOTEM will condensate when the return water temperature is less than 50°C without the need for an additional flue heat exchanger.
Based on today’s fuel costs electricity output from the co-generator will be at a similar cost to electricity from the grid, however for each kWh of electricity generated approximately 2.5 kWh of free, high-grade heat will be recovered. With ultra-low emissions, micro CHP offers a real option, especially when combined in an application that blends renewables to provide a cost-effective and future-proof method for providing the power and heating needs for commercial projects.