In open fields in Spain you can harvest around 4 kilograms of tomatoes per square metre. A Dutch high-tech greenhouse produces 80 kilograms per square metre and with four times less water.
In open fields in Spain you can harvest around 4 kilograms of tomatoes per square metre. A Dutch high-tech greenhouse produces 80 kilograms per square metre and with four times less water.
The main challenge with fruits, and especially tomatoes, is ripening versus shelf life. A tomato tastes best when it's as ripe as possible. Sweet, fragrant and full of flavor. However, at that very special time, it will burst on the vine or fall apart in your fruit basket within a day. Which is why you'll never find this quality in a supermarket. And why I grow tomatoes in my garden every summer :)
A tomato plant is roughly ~40lbs/sqft/year (hydroponic... at 40W/sqft). That's a bit higher than the 80kg/m^2 estimate, but I don't have the wattage requirements for the lower yield. But, assuming it is linear, about 20Wh/g-tomato.
And then, from a climate impact standpoint... The marginal CO2 emissions factor in the Netherlands is pretty high at ~0.6kg/kWh, so ~2kg-CO2 for every (~6oz) tomato. That is about 200-300x higher than the CO2 from trucking (refrigerated) tomatoes from Spain to Netherlands (~30-40kg-CO2/ton-tomato/1000 miles ~= 7g-CO2/tomato).
The local ecological (water+fertilizer+pesticide) impact is probably higher in Spain (vs the greenhouse construction and land use in the Netherlands), though it is hard to know how much to trade that off.
(link not from the book, but very similar) https://vaclavsmil.com/wp-content/uploads/2021/06/Tomatoes-I...
This is obviously just anecdotal, but your numbers for Spain might be too low.