Contributed by Patrick Burke Fellow: SAIRAC
A Gas Heat Pump (GHP) Air Conditioning system, is a conventional VRF (Variable Refrigerant Flow) system, where the compressor is driven by a gas engine using natural gas. The capacity is controlled by the engine speed, thereby matching the varying load to suit the required conditions.
This gas-powered HVAC System is available in both Heat Pump and Heat recovery versions to suit a broad range of design applications. The benefits of GHP are inter alia, lower CO2 emission, reduced electrical power consumption and more effective Heating.
FINDINGS AND OBSERVATIONS
In search of some general information on the internet recently, an Industry White Paper titled ‘GAS HEAT PUMP TECHNOLOGY’ caught my attention. Sponsored by some 14 local US and Canadian gas distribution companies, the paper identifies opportunities and strategies to accelerate the market acceptance of GHPs in North America.
In effect, the paper claims that GHPs have the potential to reduce energy use and greenhouse gas emissions across various climates for both the residential and commercial markets in North America. As such, these sponsor companies are eager to accelerate and advance the commercialisation of GHP technologies for Heating, Ventilation and Air Conditioning (HVAC). Given our electrical power supply issues, could this type of technology be a solution (or even a partial solution) to our problems in this regard, at the same time addressing the issues surrounding climate change?
As we know, the technology itself (VRF) is well understood in South Africa since first introduced way back in the 1980s. With many role players and suppliers of quality equipment serving our local market, VRF is probably the most dominant category of comfort cooling options currently on offer. So why then the lack of market development for VRF gas heat pump technology in South Africa? While there is probably a call locally (albeit small) for this type of VRF System, no one to my knowledge, is actively marketing their product – even though several Leading HVAC companies manufacture this type of product.
One would think that this would receive serious consideration given our crippling electrical power situation. Not so! Obtaining any information on the subject is tantamount to pulling teeth. From all accounts, even the local guys have no marketing strategy from their principals in this regard.
- Could it be the availability of LNG / LPG gas? Surely not! This is currently produced in Mozambique, Mossel Bay and elsewhere, and piped and / or transported into our major cities and commercial centres, apparently without any major issues.
- Could it be a matter of running costs, LNG versus electrical power? Maybe it’s simply not economically viable locally at today’s comparative rates. By the way, LNG is substantially cheaper than electrical power in the US.
- Could it be the cost of setting up the required site infrastructure and safety requirements? In this regard, many local commercial buildings and shopping malls are already piped for LNG to serve their restaurant kitchens, hot water boilers etc.
- Capital equipment costs: Gas engine VRF versus standard electric-powered VRF equipment. What is the difference in rands and cents?
- Operational costs: With regard to maintenance and repairs, gas engine versus standard electric VRF equipment, suppliers of this equipment claim 10 000 hours of maintenance-free operation or as long as five years.
- In weighing up the pros and cons, my scrutiny has yielded the following prognosis, based on the information at my disposal.
- As already stated, LNG / LPG is available in bulk supply in all major centres.
- From all accounts, the cost of LNG / LPG compares favourably with electrical power (kg versus kWh, based on available information). In this regard, international sources indicate that natural gas VRF systems produce substantially lower overall costs.
- The cost of site establishment and safety requirements will surely prove of little consequence when taking into account the inconvenience of load shedding and power outages. It’s worth noting that an LNG / LPG gas storage facility would be more expensive to establish, since more space is required due to its larger volume.
- As far as capital equipment costs are concerned, in South Africa we have no current supply source on which to make suitable cost comparisons. However, this could be easily ascertained through any one of the local major VRF equipment suppliers. To my mind however, pricing should be reasonably competitive given the close similarity of the technology applied in both cases (electric driven versus gas driven VRF).
Before we all get too excited, there are some concerns, not with VRF technology, but with the long-term supply of natural gas in South Africa. This could well be a serious future stumbling block. A Business Tech article on energy recently (17 November 2023) alluded to a plunge in South Africa’s natural gas supply within the next three to four years, claiming that the shortfall could well trigger the country’s next economic crisis. Nevertheless, a level of clarity is needed sooner rather than later, as to where additional gas supplies can be sourced, if such a crisis is to be avoided. In the longer term, the supply prospects look more promising, with a new gas field discovered off the West Coast (which could well be
in operation by 2030).
In conclusion, it’s good to know that a gas engine VRF derivative is available and is well developed. Whether or not it will suit South Africa’s alternate energy requirements going forward, depends on a number of factors, factors that urgently require a decisive and fast-track approach by the powers that be. On a personal note , I would like to see the development of a dual-drive VRF arrangement (combined electrical / gas driven compressor(s) with an easy auto change-over system). However, this is probably wishful thinking on my part based on our country’s unique power supply situation and particular energy challenges.