Every day, the Sun sends to Earth around 140 watts per square meter (averaged over 24 hours at the surface). This energy is over a range of frequencies (called black-body radiation), minus a few bands taken out by water, carbon dioxide and other compounds in the atmosphere.
If you had a good use for all of that energy, you might be prepared to pay up to 20 cents per kilowatt hour, as you do for some of your delivered electricity. Some quick maths shows that every hectare of farmland in New Zealand receives $2.4 million retail dollars worth of energy per year, from the Sun.
If you covered a hectare of paddock with photovoltaic solar panels, at current efficiency of say 25%, priced at $2 per watt for the panels (capacity of 600kW per Ha), you could perhaps generate 200kW per hectare on average in NZ (retail $40 per hour, or $350,000/Ha/yr), but the capital cost of the panels and hardware would be at least $2million. If you wanted to sell the power, it might only be worth 10c per kWHr at wholesale rates, and with the shortish lifetime of panels (15-20 yrs), it starts to look less exciting.
But why would you cover up a hectare of good farmland with solar panels anyway? By using your land for dairying (for example) to produce milksolids, and excluding brought-in feeds, fuel, electricity and assuming no meat production, it is normal to send off-farm just 0.06% of the Suns’ energy hitting each hectare. It’s a bit like turning on a 2400W heater in your lounge and getting under two watts of heating from it! You would hardly know it was going. Annual profit per hectare from dairy farming can reach NZ$3,000 to $5,000 or so.
From an energy efficiency point of view, farming with ruminants only succeeds because humans value the outputs highly, and most of the vast energy used comes free from the Sun. (On the positive side, it is also generally a pleasant use for land, and ruminants are good at cropping pasture from hills).
Knowing this efficiency issue, farmers can look at ways of increasing profitability by effectively using more of the sunshine that they receive. Aim to have no pugging, by whatever means possible. It might be far cheaper to just put in a feed pad or standoff area, than to lose several hectares of farm for several weeks of each year (of course serious pugging can take years to correct). Herd homes or sheltered areas keep stock cooler in summer and warmer in winter, and this helps with their feed conversion efficiency.
Pay close attention to your soil structure and pasture and correct imbalances. It’s possible that the benefits of increasing soil biological activity is an overlooked factor (worms, microbes etc). Look at a wider variety of forages that cope with all the weather extremes seen on your farm, as the climate slowly changes.
Why pay gold for your water heating power when you have so much spare area near the dairy for a few evacuated solar tubes? These systems are getting cheaper all the time, and the payback period is getting down below five years. Keep an eye on the photovoltaic cell prices - these are coming down sharply as China starts solving its energy issues. Another interesting area is the extraction of biodiesel from algae in stirred ponds or pumped tubing systems. This is over 1000 times more efficient than growing irrigated crops to produce ethanol for example. The next few years will see big changes in this area.
Don’t forget that you already have a huge solar panel working there on your farm, and if you could just increase its very low efficiency, it would improve the bottom line.
If you had a good use for all of that energy, you might be prepared to pay up to 20 cents per kilowatt hour, as you do for some of your delivered electricity. Some quick maths shows that every hectare of farmland in New Zealand receives $2.4 million retail dollars worth of energy per year, from the Sun.
If you covered a hectare of paddock with photovoltaic solar panels, at current efficiency of say 25%, priced at $2 per watt for the panels (capacity of 600kW per Ha), you could perhaps generate 200kW per hectare on average in NZ (retail $40 per hour, or $350,000/Ha/yr), but the capital cost of the panels and hardware would be at least $2million. If you wanted to sell the power, it might only be worth 10c per kWHr at wholesale rates, and with the shortish lifetime of panels (15-20 yrs), it starts to look less exciting.
But why would you cover up a hectare of good farmland with solar panels anyway? By using your land for dairying (for example) to produce milksolids, and excluding brought-in feeds, fuel, electricity and assuming no meat production, it is normal to send off-farm just 0.06% of the Suns’ energy hitting each hectare. It’s a bit like turning on a 2400W heater in your lounge and getting under two watts of heating from it! You would hardly know it was going. Annual profit per hectare from dairy farming can reach NZ$3,000 to $5,000 or so.
From an energy efficiency point of view, farming with ruminants only succeeds because humans value the outputs highly, and most of the vast energy used comes free from the Sun. (On the positive side, it is also generally a pleasant use for land, and ruminants are good at cropping pasture from hills).
Knowing this efficiency issue, farmers can look at ways of increasing profitability by effectively using more of the sunshine that they receive. Aim to have no pugging, by whatever means possible. It might be far cheaper to just put in a feed pad or standoff area, than to lose several hectares of farm for several weeks of each year (of course serious pugging can take years to correct). Herd homes or sheltered areas keep stock cooler in summer and warmer in winter, and this helps with their feed conversion efficiency.
Pay close attention to your soil structure and pasture and correct imbalances. It’s possible that the benefits of increasing soil biological activity is an overlooked factor (worms, microbes etc). Look at a wider variety of forages that cope with all the weather extremes seen on your farm, as the climate slowly changes.
Why pay gold for your water heating power when you have so much spare area near the dairy for a few evacuated solar tubes? These systems are getting cheaper all the time, and the payback period is getting down below five years. Keep an eye on the photovoltaic cell prices - these are coming down sharply as China starts solving its energy issues. Another interesting area is the extraction of biodiesel from algae in stirred ponds or pumped tubing systems. This is over 1000 times more efficient than growing irrigated crops to produce ethanol for example. The next few years will see big changes in this area.
Don’t forget that you already have a huge solar panel working there on your farm, and if you could just increase its very low efficiency, it would improve the bottom line.
Comment