With wholesale natural gas prices hurting the bottom line, and no pricing certainty yet in sight, large businesses are moving away from being solely dependent on natural gas for their heating requirements. As they do this, they quickly come to realise that there are viable alternative solutions that can dramatically slash their energy bills.
Most people think that solar electricity is the answer to their problem, when in fact, it may be one of the least economic solutions to implement for applications with high heating demand. With the latest advances in technology, a far more cost efficient and effective solution is to generate energy from a solar thermal (hot water) heating system that is up to 450% more efficient than solar electricity, and costs almost nothing to run and maintain.
Large scale solar thermal heating systems (such as that depicted above) are similar in principle to domestic solar hot water systems, but on a much larger scale. They generate enough heat to cover most of the heating demand of a business like dairy farms, poultry farms and greenhouses, or any business that requires a considerable amount of heating below 100˚C.
Heating and cooling your space / water from direct sunlight through solar thermal collectors is basically FREE energy, as the only running cost to keep the system operational is a small hot water pump (flow rate less than 0.005 l/s per m2 of solar collector).
Solar thermal heating and cooling is now an advanced solar technology thanks to the use of innovative absorber technology, and is exceptionally cost-effective over its life-cycle. Solar thermal heating and cooling can be used to condition the air space of any building – from a single residence to a whole retirement village, and even large greenhouses or poultry sheds.
The main components of a solar thermal (heating/cooling) system are shown below:
Water heated by the solar thermal collectors is stored in a hot water storage tank and used by the end user when required (day and/or night). The hot water energy storage in this system is used like a battery to match energy generation and demand, and unlike electric battery storage, it doesn’t cost a fortune and doesn’t die before paying itself back. When there is insufficient solar irradiance, water heating is supplemented by an auxiliary booster/boiler to ensure 24/7 availability of hot water.
When a solar thermal system is combined with an absorption chiller, the generated hot water from the sun can be used to create chilled water for cooling applications. The fascinating fact about this form of cooling is that the solar thermal cooling system capacity and efficiency is highest when the outdoor temperature is warmest!
Savosolar of Finland, manufactures the world’s most efficient large-scale solar thermal collectors (See Figure 1), and has delivered major projects in seventeen countries across four continents. GeoHeat Australia Pty Ltd has partnered with Savosolar and brought the latest solar thermal technology and expertise into Australia and New Zealand.
Figure 1: Absorber for a large scale solar thermal collector
The Savosolar solar thermal collectors use an innovative and award winning absorber that generates up to 1110kWh p.a. of heating energy per m2 of solar collector – that’s more than five times the amount of energy compared with an equivalently sized solar electricity (PV) system!
The Savosolar absorber is a uniquely designed nano-coated aluminium multi-port channel section (see Figure 2) that allows fluid in the solar panel to be in direct contact with the sun’s energy across the entire solar heated surface! This design eliminates the high thermal gradients and heat losses of conventional absorbers, and maximizes the thermal efficiency of the solar thermal collector. Savosolars’ collectors are approximately 50% more efficient than conventional flat plate collectors (with copper pipe and fin), come with a 10 year manufacturer’s performance warranty and have an expected life span of 20 years.
Figure 2: Savosolar’s innovative absorber delivers the highest efficiency in the market
Summary of Advantages
For any business with a large heating and/or cooling energy demand, the advantages of solar thermal systems compared with other energy resources are as follows:
Free Heating: A solar thermal system provides free heating energy and is largely maintenance free. It has no moving parts, except for a small pump (flow rate 0.005 L/s/m2 of collector surface area to keep water in circulation.
Free Cooling: A solar thermal system, combined with an absorption chiller, will deliver free cooling. The overall solar thermal cooling system capacity and efficiency is highest when the outdoor temperature is warmest and there is more demand for cooling! A typical 600kW absorption chiller can convert as much as 83% of free solar hot water to chilled water at 7C using less than 2.5kW electricity.
More than five times the thermal energy: In practice, Savosolar thermal collectors can deliver as much as 1110 kWh per m2 p.a. of collector, compared with just 200kWh per m2 p.a. of solar electricity panels! In other words, Savosolar panels generate 5.4 times the energy per unit of space when heating is the biggest energy cost for businesses.
Simple and Cheap Storage: Solar thermal systems generate energy in the form of hot water that is stored in large hot water tanks. Large storage tanks cost approximately $300-$600/m3 hot water capacity, or less than $8/kWh. Electric storage batteries can cost $800/kWh. Hot water storage tanks can be used an unlimited number of times within their expected 25 year life span, whereas batteries only last around ten years if they are recharged not more than once a day.
Suitable for any land: Solar thermal collectors can be installed on roof tops, hills and sloping sites.
Energy Independence: Solar thermal systems can bring real energy independence. If for any reason in the future, Australia is in short supply of gas for domestic market, this won’t affect business. Solar thermal systems already provide a huge operating cost advantage over their life time, and will continue to do more so, as gas prices increase further.
Low Installed Cost: Solar thermal systems (without any subsidy), depending on the system size, cost about $400/m2. Local and federal governments also provide low-interest loans in support of installation of renewable energy systems. Organisations such as the Clean Energy Finance Corporation and Sustainable Melbourne Fund are backed by government bodies in providing these services.
Long Warranty Period & Life Expectancy: The performance of Savosolar thermal collectors is guaranteed for 10 years, with a life expectancy beyond 20 years.
