Research Project Summary Information
A Study of Liquid Fuel Based Micro-CHP Systems
Brookhaven National Lab
A large number of single and small residential buildings in New York State use oil as the primary source for heating (space and domestic hot water). On the other hand, very few residences generate any part of their electrical power requirements. Micro-CHP (micro Combined Heat & Power) is the simultaneous production of heat and electricity from a single source/fuel. Such systems are in an early stage of development and primarily use natural gas as the fuel. In a typically CHP installation the installed CHP system is integrated with the existing space heating and/or domestic hot water system. An opportunity exists for the development of micro-CHP systems using heating oil (conventional, diesel, or biofuels). For oil fired micro-CHP systems to be commercially viable the economic benefits (energy savings), emissions reductions, system reliability, noise attenuation and integration with existing heating system needs to be demonstrated.
The Contractor will perform two specific studies; an experimental study using a diesel engine and an analytical study that will examine potential energy savings and benefits of micro-CHP systems for ‘typical’ locations in New York State. For the experiment, a small diesel engine will be purchased to drive an electric generator using two fuel sources; on-road diesel and biodiesel blends. The possibility of operating the engine in a Homogeneous Charge Compression Ignition (HCCI) mode will be explored, which can enable the reduction of smoke, particularly NOx, without exhaust treatment. This will be done by injecting fuel into the engine air intake, using a heated atomizer to promote vaporization of the fuel before entering the engine cylinder. The engine efficiency and emissions will be measured under different electrical loads during these scenarios. For the analytical study, the Contractor will use a sub-contractor to map the performance of a micro-CHP system in two ‘typical’ locations, one representing Albany, NY and the other Long Island, NY.
Results from the experimental work and analytical work indicate an oil-fired micro CHP system has the potential to produce energy savings whether the CHP system is used to supply domestic hot water or to supply both hot water and space heat. Employing homogeneous charge compression ignition (HCCI), engine smoke and NOx emissions can be lowered for both diesel and biodiesel blends. A 2 kW micro-CHP system with an electrical efficiency of 25%, installed in a typical single family home in NYS could save about 30MBtu of energy per year for a combined space heat and domestic hot water system. This corresponds to annual energy savings of about 210 gallons oil equivalent per year. Commercial viability requires additional engine optimization for HCCI operation, demonstration of reliability and minimal maintenance, and integration with existing oil heating systems and controls. The economics of the system are not obvious at present and would have to be established based on market forces and conditions.
Experimental study revealed the following:
– engine can be operated in normal and HCCI modes using both diesel and biodiesel blends
– biodiesel blends produce lower smoke levels than diesel in both modes of operation
– NOx levels are lower with HCCI mode of operation than with normal mode for both fuels
– Engine efficiency was lower in the HCCI mode of operation although system parameters were not optimized
– biodiesel has approximately a 10% lower heating value than diesel fuel, the flow rate through the injector is higher for the same power output, and the injection system seems able to handle it in the range of loads that were tested
Analytical study revealed the following:
– Internal combustion engine is the only proven technology as a prime mover; presently no diesel engine for this case is currently manufactured or available in the U.S.
– The use of a micro-CHP system results in primary energy savings (either domestic hot water or space heat) for both Albany and Long Island locations, and size of thermal storage had no affect
– Example scenario; Using a two kW CHP system with electrical efficiency of 25%, a typical house will save 30 MMBtu/year for combined space heat and dhw, corresponding to approximately 210 gallons oil/year saved
– Savings increase with prime mover power capacity up to the two kW power output, then savings became flat, suggesting the smaller low power engine was a good choice for testing
– Net metering (power returned to grid in excess of load)
Brookhaven National Lab
32 Lewis Road Building 130
Upton, NY 11973
Heating, Ventilation, & Air Conditioning
NYSERDA Contact Information
R&D - Buildings Research