Green tomatoes
10/07/09 09:43
Most of us like our tomatoes red - the deep red that actually smells tomatoe-y! That’s exactly the sort of tomatoes that Ken Parkinson and his wife Jan grow at Siddlesham for Waitrose but, since October 2007, their glasshouse operation has taken on a new green image. The Parkinsons have invested heavily in a Swedish gas turbine system which looks set to deliver the greenest tomatoes in the area.
The basic concept of the gas turbine is very simple. Instead of burning gas in a boiler to produce heat for the glasshouses they are now burning it in a turbine to generate electricity, a small amount of which is used to power the nursery. The rest is sold to Waitrose, through a company called Green Energy, to power their Rickmansworth store. It is delivered through the National Grid and the amount is metered using wi-fi technology on the output leaving the nursery.
As turbines spin during operation they create heat which is used in the nursery’s hot water system, either being delivered straight into the glasshouses or stored in an insulated 80,000 litre tank for use during the night. The high temperature burning of the gas in the turbines ensures that the exhaust from the system is almost pure carbon dioxide which enriches the atmosphere in the glasshouses, encouraging the tomato plants to grow. Ken is expecting that the purity of the atmosphere will lead to larger fruits and may mean that he is able to increase the stocking density in the nursery with consequently higher yields. Ken and Jan currently have 35,000 plants in their glasshouses so even a 2-3% improvement in yield will be significant. The near perfect atmosphere will also make Ken’s job of getting 8 fruits to ripen perfectly on a truss a little easier. “With 8 fruits setting it is essential for us to get them all to the peak of ripeness at the same time so that the whole truss delivers a perfect tomato flavour and eating experience. It’s not easy to achieve, but it’s what makes a successful tomato for both the customer and the grower” he explained.
Ken and Jan are starting to measure the success of their new turbine. There have, of course, been teething problems as there are with any new technology or system, but they already have some compelling facts at their fingertips. They are generating electricity at over 90% efficiency, whereas the average for the National Grid is 40%. By the spring of 2008 despite the initial problems, they had exported 300 times more power than they had used since installing the turbine.
Since then, fuel prices rocketed and the cost of running the turbines was under discussion. However, stabilising prices since the depths of the winter of 2008/9 have set the turbines back on track, although gas prices will be critical to the long-term success of the plant. It isn’t easy being green but I am full of admiration for Ken and Jan for taking this huge step towards greener production and sticking with it. Most of us can only judge our tomatoes by colour and flavour, but green-ness certainly plays a big part in my red tomato choices.
The basic concept of the gas turbine is very simple. Instead of burning gas in a boiler to produce heat for the glasshouses they are now burning it in a turbine to generate electricity, a small amount of which is used to power the nursery. The rest is sold to Waitrose, through a company called Green Energy, to power their Rickmansworth store. It is delivered through the National Grid and the amount is metered using wi-fi technology on the output leaving the nursery.
As turbines spin during operation they create heat which is used in the nursery’s hot water system, either being delivered straight into the glasshouses or stored in an insulated 80,000 litre tank for use during the night. The high temperature burning of the gas in the turbines ensures that the exhaust from the system is almost pure carbon dioxide which enriches the atmosphere in the glasshouses, encouraging the tomato plants to grow. Ken is expecting that the purity of the atmosphere will lead to larger fruits and may mean that he is able to increase the stocking density in the nursery with consequently higher yields. Ken and Jan currently have 35,000 plants in their glasshouses so even a 2-3% improvement in yield will be significant. The near perfect atmosphere will also make Ken’s job of getting 8 fruits to ripen perfectly on a truss a little easier. “With 8 fruits setting it is essential for us to get them all to the peak of ripeness at the same time so that the whole truss delivers a perfect tomato flavour and eating experience. It’s not easy to achieve, but it’s what makes a successful tomato for both the customer and the grower” he explained.
Ken and Jan are starting to measure the success of their new turbine. There have, of course, been teething problems as there are with any new technology or system, but they already have some compelling facts at their fingertips. They are generating electricity at over 90% efficiency, whereas the average for the National Grid is 40%. By the spring of 2008 despite the initial problems, they had exported 300 times more power than they had used since installing the turbine.
Since then, fuel prices rocketed and the cost of running the turbines was under discussion. However, stabilising prices since the depths of the winter of 2008/9 have set the turbines back on track, although gas prices will be critical to the long-term success of the plant. It isn’t easy being green but I am full of admiration for Ken and Jan for taking this huge step towards greener production and sticking with it. Most of us can only judge our tomatoes by colour and flavour, but green-ness certainly plays a big part in my red tomato choices.