SESSA member Dr Anthony Keen of Cape Town has been named – for the second time – as the winner of the Energy Savings in Households category at the 2011 eta Awards.
A medical doctor, with no electrical engineering experience, Dr Keen and his family have strived, since 1984, to bring down their monthly electricity consumption. Their success rate is a phenomenal 71%, from 1 263kWh to 350kWh, and has been achieved using a system designed and mostly implemented by Dr Keen himself.
They’ve also pioneered the exploration in this country of how to best manage energy from three sources – PV, battery and grid – to satisfy the very variable demands of a home while living mostly by sunpower.
The awards, run by Eskom and the Department of Energy for the past 21 years, take their name from (eta), the Greek symbol for efficiency. Their purpose is to reward exceptional effort in the more efficient use of energy by individuals, students, companies or other institutions.
Another SESSA member, Geyserwise’s Meinhard Fourie, was the runner up in the Innovation category in this year’s awards while MLT Drives, also a SESSA member, provided the inverter for the ground-breaking installation at Villiera Wines. Simon Grier of Villiera Wines was named runner up in the Efficiency Champion: Industrial category.
Meinhard’s recognition was for the development of an energy efficient swimming pool pump motor which is achieving savings of approximately 3kWh per day without compromising on run times.
The innovative team at Villiera, led by Grier, covered three of the roofs at the Stellenbosch-based winery with 539 solar modules. These now generate enough electricity to supply one third of the requirement of the farm during its peak period, harvest. This includes providing energy to staff housing, offices, kitchens, processing and bottling facilities, cellars and even its cooling and irrigation systems. The system also supplies much of the electricity requirements for the remainder of the year. The 900 m2 of solar panels, capable of providing more than 132kW of power per day, were installed at a huge cost to the winery, but Grier calculates they will pay for themselves within seven years.
Dedicated to the use of renewable energy and energy efficiency technologies including solar-based energies (such as photovoltaics, thermal heating and cooling), wind, bioenergy and hydro, SESSA (Sustainable Energy Society of Southern Africa) was founded in 1974. It is one of 50 National Sections and the duly appointed Africa office of the International Solar Energy Society (ISES). ISES is regarded as the premier body in solar energy with members in over 100 countries.
The Keen family’s obsession with saving energy started when they returned to the Cape after sailing a small yacht from the Mother City to Scotland and back.
“After living for many years with abundant cheap grid power readily available, we understandably never gave a second thought to energy, where it comes from, how much it costs and what damage generating it does,” said Dr Keen.
“Months on a yacht with limited access to fresh water and energy changed all that. In fact, the most commonly asked question in the household is ‘Is there enough sun to switch on the washing machine?”
‘The Project’ – as it is called by the family – has been run as an experimental exercise with everything recorded and written up as a research project. The objective is to ‘show by doing’ by sharing the results with as many people and groups as possible.
It started with the installation of a solar water heating system (SWH) and a wood burning fireplace in 1984. The main SWH system was professionally installed to Dr Keen’s design while he personally converted a smaller existing kitchen geyser to solar. As a result of the SWH, the Keen family switched off all power to their geysers for nine months of the year cutting electricity consumption by 44% averaged over a year.
“Importantly, the system was paid off in six years – without any subsidy – and still operating 27 years later with no servicing,” said Dr Keen. “This demonstrates the immediate impact and durability of a well-designed SWH.”
After the installation of the SWH, Dr Keen set about customising his home and achieved a further 20% reduction in energy consumption:
- ·appliances were replaced when necessary with energy efficient versions
- ·compact fluorescent lighting was installed
- ·ceilings, geysers and hot water pipes were insulated
- ·doors and windows were made draught-proof
- ·a timing switch was installed
He then addressed the swimming pool pump, a major consumer of energy:
- ·a larger pump, filter and chlorinating system cut the running time could be cut to 4 hours a day
- ·covering the pool for winter (seven months) under an innovative home-fashioned light-proof cover floating on re-cycled plastic drums to shed rainwater and leaves meant the pump could be turned off without compromising water quality or clarity
These final steps saved another 7% to bring the average annual monthly consumption down from 1263 to 350 kWh. The overall 71% reduction earned Dr Keen the eta award in 2008 for Suburban Power Saving.
2009 brought a new challenge – generating energy and storing it for future use – and his work in meeting it netted Dr Keen the 2011 eta Award. Based on the family’s known consumption patterns and appliances, he designed a photovoltaic system (PV) comprising 20 PV panels (3.8 kWp output) installed by a professional on the north-facing roof.
A sophisticated inverter from SESSA member MLT Drives and a lead/acid battery pack supplied the power to the house. The inverter included a programmable energy management system and a logging system as well as a wificomputer/internet connection.
Major electrical heating requirements – stove, oven and geyser top-up – were beyond PV solar power and were therefore for Dr Keen’s research purposes considered outside the solar power system; power for these were supplied by the grid.
The new solar power system supplied the remainder of the house: all lights, all power sockets with appliances like kettles, microwave ovens, mixers, refrigerator, dishwasher, washing machine, TV, hifi, computers, swimming pool pump, garage doors and sliding gates, a borehole pump and garden distributing pump, and power tools including the chain saw used for cutting firewood. Over time, a gas hob was introduced and the stove therefore moved off the grid and an LPG-fuelled direct current generator courtesy Professor PJ Lloyd of CPUT and Afrox, enabled more complete off-grid operation of the solar system.
“With the new system, I wanted to explore how best to manage energy from three sources – PV, battery and grid – to satisfy the very variable demands of a home while living mostly by sunpower,” explained Dr Keen.
“Two strategies were developed. In the first instance, the house was supplied by PV and/or batteries with grid power as a back-up. This strategy was titled ‘Off-Grid’ and allowed for daily cycling of the batteries. Secondly, there was ‘Net-Metering’; this entailed a manual change over so that the house could draw power from PV and/or grid, with battery as the back-up.
“Unfortunately, true operation in such named modes was not possible as the house remained connected to the grid and net metering was not permitted by the grid operator, the City of Cape Town.”
Results for the first year of operation included:
- ·PV panels generating more kWh than were used in the house, yet grid/genset energy was still needed because of a disparity between time of production and time of consumption with limited storage capacity
- ·lead/acid battery inefficiency (only 54%)
- ·an overall capacity factor was 20%, demonstrating PV’s suitability as a solar option for Cape Town
- ·summer production being double that of winter, resulting in a considerable surplus of energy during the warmer months
Dr Keen explained further: “The off-grid strategy permitted greatest use of sun power but did require load management. That is, we had to learn to time our energy consumption to co-coincide with peak energy production periods, or ‘live under the red PV production curve’ shown in the graphic below, and when we got it right, we were living off the grid. By contrast, net-metering, once set up, required no operator input, and was sometimes used in poor weather – see the ‘winter’ figure below – and by house-sitters, but used grid every evening.
“Every kW generated in a grid-linked PV system, irrespective of where it is consumed, saves one kW of Eskom power and contributes to ‘demand side management’,” summarised Dr Keen. “My next step in the family’s on-going relationship with energy is to better storage capacity and technology, for example lithium batteries, and working out how to automate the off-grid/net-metering changeover according to sun availability. Once we’ve achieved that, we’ll no longer have to wait for the sun to rise in order to do our washing!”
Dr Keen urges City of Cape Town to get FiT
At the moment, the City of Cape Town does not permit surplus electricity to be fed back into its grid . However, Dr Keen and others – including Green Cape and Sustainable Energy Society of Southern Africa (SESSA) – are working with the municipality to change this , initially with a net metering strategy but hopefully leading to a Feed-in-Tariff (FiT) system . The Danish co-operatives saw the benefits of a ‘feed-in tariff’ system in the early 1990s; the Germans adopted it in 1993.
In essence, FiT:
- ·Obliges the nearest net-owner to buy all renewable energy at a fixed price that is related to renewable energy production costs plus reasonable profit
- ·Every two years, prices are reviewed, but only apply for new contracts. There’s a 20 year price guarantee covered by a standard contract and standard connecting conditions on all contracts.
- ·The producer’s own on-site renewable energy consumption counts as being delivered to the grid.
- ·Municipalities and utilities are also allowed to join the programme under same conditions.