WEBVTT 1 00:00:00.990 --> 00:00:04.910 The grapes being harvested here are not just any grapes. 2 00:00:04.910 --> 00:00:09.190 They're part of a pilot project for a very special Riesling vintage. 3 00:00:09.590 --> 00:00:12.140 At a vineyard attached to Geisenheim University in 4 00:00:12.150 --> 00:00:15.470 the Rheingau region of western Germany, scientists are trying to 5 00:00:15.470 --> 00:00:19.470 find out how the fruit develops in the shade of a three-meter-high 6 00:00:19.480 --> 00:00:23.430 agrivoltaic system - also called an 'Agri-PV' array. 7 00:00:23.910 --> 00:00:28.370 In addition to the shaded trial area, grapes in a control field are 8 00:00:28.370 --> 00:00:30.350 ripening under normal conditions. 9 00:00:30.760 --> 00:00:33.880 Increasingly, warm summers have accelerated the process. 10 00:00:36.550 --> 00:00:40.180 We have earlier harvests, so in the last couple of decades, 11 00:00:40.190 --> 00:00:45.560 the grapes have on average ripened around 30 to 40 days faster than before. 12 00:00:45.870 --> 00:00:48.580 The warmer temperatures also change the aroma of 13 00:00:48.590 --> 00:00:51.510 the varieties grown here. 14 00:00:52.310 --> 00:00:55.910 The research involves nothing less than the future of wine. 15 00:00:55.910 --> 00:00:57.540 Or at least of Riesling wines. 16 00:00:57.550 --> 00:01:00.140 And not just here in the Rheingau region. 17 00:01:00.350 --> 00:01:03.670 Climate impact researcher Claudia Kammann has observed more 18 00:01:03.670 --> 00:01:05.530 frequent extreme weather. 19 00:01:05.550 --> 00:01:08.790 July 2023, for example, was the hottest on record since 20 00:01:08.800 --> 00:01:13.360 measurements began in 1885. 21 00:01:13.959 --> 00:01:17.310 Weather-wise, we had a few challenges. 22 00:01:17.319 --> 00:01:21.550 First we had a very dry phase from mid-May to mid-June. 23 00:01:21.550 --> 00:01:24.300 Then there was a short thunderstorm, and after that it was 24 00:01:24.319 --> 00:01:27.270 really hot and dry again for a long time. 25 00:01:27.390 --> 00:01:30.020 So there were these gaps in precipitation. 26 00:01:30.030 --> 00:01:33.246 And everything highlighted in red - the temperatures - they're all 27 00:01:33.246 --> 00:01:37.163 significantly higher than the long-term average. 28 00:01:37.373 --> 00:01:41.800 Claudia Kammann thinks many people underestimate how severe climate 29 00:01:41.800 --> 00:01:43.220 change could be. 30 00:01:43.240 --> 00:01:47.200 In the future, extreme weather events like heavy rain and hail, 31 00:01:47.200 --> 00:01:50.560 followed by heatwaves and droughts, will occur more often. 32 00:01:51.930 --> 00:01:56.396 We're at a point where we really notice this heating-up, and have to 33 00:01:56.396 --> 00:01:59.876 contend with extreme consequences with stuff that's never happened before, 34 00:01:59.876 --> 00:02:02.470 situations that are new. 35 00:02:02.470 --> 00:02:06.946 For example, we've never seen sunburn on the vines before. 36 00:02:07.757 --> 00:02:11.880 The semi-transparent photovoltaic modules are designed to protect 37 00:02:11.880 --> 00:02:15.240 the vines from too much sun and prevent early ripening. 38 00:02:15.240 --> 00:02:19.079 Will they work? Manfred Stoll hopes so. 39 00:02:19.613 --> 00:02:24.570 Of course, it was clear to me from the outset that the microclimate in 40 00:02:24.590 --> 00:02:27.967 particular would be altered by the protected conditions. 41 00:02:28.630 --> 00:02:31.940 Specifically, that it would be cooler under the photovoltaic 42 00:02:31.950 --> 00:02:36.580 system during the day, but that at night, the temperature would be 43 00:02:36.590 --> 00:02:39.663 slightly higher due to soil radiation. 44 00:02:40.120 --> 00:02:43.280 In other words, that the semi-transparent modules 45 00:02:43.280 --> 00:02:48.213 would naturally change both the light quality and intensity. 46 00:02:50.430 --> 00:02:54.500 But some of the differences caused by the altered climatic conditions 47 00:02:54.500 --> 00:02:57.770 under the modules surprised the scientists. 48 00:02:57.790 --> 00:03:01.880 In the first year, Lucia Garstka observed that the vines produced 49 00:03:01.889 --> 00:03:04.683 more leaf surface area. 50 00:03:07.560 --> 00:03:12.200 This is actually a completely natural reaction on the part of the plants. 51 00:03:12.200 --> 00:03:15.870 If less light is available, they respond by increasing the amount of 52 00:03:15.880 --> 00:03:17.870 area used for light absorption. 53 00:03:17.880 --> 00:03:20.130 So they produce larger leaves. 54 00:03:21.110 --> 00:03:24.020 Another observation was that the modules altered the 55 00:03:24.030 --> 00:03:27.430 distribution of water in the vineyard during and after rainfall, 56 00:03:27.550 --> 00:03:30.790 apparently in favor of the thirsty vines. 57 00:03:31.680 --> 00:03:35.800 We saw that moisture in the system lasts much longer. 58 00:03:35.800 --> 00:03:40.380 The photovoltaic modules above the vines keep them mostly dry, but 59 00:03:40.390 --> 00:03:43.560 between the modules - where there's a gap - it rains in. 60 00:03:44.040 --> 00:03:49.030 And after that water hits the ground, it remains there longer. 61 00:03:51.230 --> 00:03:55.260 It's been a few days - if not weeks - since the last rain, and in 62 00:03:55.260 --> 00:03:57.700 the control area everything has dried out again . 63 00:03:57.710 --> 00:04:00.847 But here the soil is still moist. 64 00:04:01.280 --> 00:04:05.450 If the project is successful, could agricultural landscapes one 65 00:04:05.460 --> 00:04:08.670 day disappear beneath hi-tech structures? 66 00:04:08.680 --> 00:04:12.680 Covered by photovoltaic arrays, instead of plastic sheeting 67 00:04:12.680 --> 00:04:14.347 like in southern Europe? 68 00:04:17.640 --> 00:04:21.790 If there were islands of solar cells here in this area 69 00:04:21.800 --> 00:04:25.760 not covering everything, but islands - where hikers know they can shelter 70 00:04:25.760 --> 00:04:26.970 from the scorching sun... 71 00:04:26.980 --> 00:04:31.830 then that would be something I would find very attractive as a tourist. 72 00:04:31.830 --> 00:04:34.380 If I knew I could always find a patch of shade in 73 00:04:34.390 --> 00:04:36.820 an island of biodiversity. 74 00:04:36.830 --> 00:04:39.830 One where I could charge my cell phone or my bike battery. 75 00:04:39.830 --> 00:04:43.333 That would also be an option. 76 00:04:44.677 --> 00:04:48.510 Vine growth yielded important findings for the scientists. 77 00:04:48.510 --> 00:04:51.790 But they're also curious to see what delayed ripening under 78 00:04:51.800 --> 00:04:55.230 the modules means for the taste and sugar content of 79 00:04:55.230 --> 00:04:58.580 the freshly-pressed juice, or "must". 80 00:04:58.589 --> 00:05:02.860 More sunshine now drives the sugar content of the grapes here so high 81 00:05:02.860 --> 00:05:06.020 that the resulting wine contains a lot of alcohol. 82 00:05:06.589 --> 00:05:09.470 The system could bring back traditionally dry, 83 00:05:09.480 --> 00:05:11.990 low-alcohol Rieslings. 84 00:05:13.430 --> 00:05:17.430 The fermentation is just coming to an end, so it still has a lot 85 00:05:17.430 --> 00:05:20.063 of intense aromas. 86 00:05:22.589 --> 00:05:26.980 What we're trying to do with the system is to turn Riesling back 87 00:05:26.990 --> 00:05:29.630 into the wine it used to be. 88 00:05:30.839 --> 00:05:35.529 Our hypothesis is that if we achieve a delay in ripening, 89 00:05:35.540 --> 00:05:39.790 then we'll achieve a profile perhaps more similar to the Riesling 90 00:05:39.800 --> 00:05:43.120 we used to know back in the old days. 91 00:05:44.720 --> 00:05:49.160 Photovoltaics in viticulture... an opportunity to create wine that is 92 00:05:49.160 --> 00:05:50.670 fit for the future. 93 00:05:50.680 --> 00:05:54.839 And that harks back to the past of the world-famous German Riesling, 94 00:05:54.839 --> 00:05:58.920 which could otherwise someday disappear due to climate change.