Big headlines in Nature last week: ” Emissions are still rising: disaster up the cuts “And” Leaders at climate summit get bad news: CO2 emissions are rising again “.
Astonishing that may not be, however: if the economy continues to grow, and therefore consumption, energy and material use will increase, and related CO2 emissions. Yes, but we install a lot of renewable energy, the PV panels can not be produced fats enough…? Aha. But that is part of the problem ….! The production of PV panels also causes CO2 emissions. And that is direct, today. And it takes several years before the panel’s energy output has compensated for its own CO2. But more importantly, if the production or installation of solar panels continues to rise, the CO2 emissions will also continue to rise, since before compensated, a new , and larger batch, will have increased emissions. Suppose the EROI (energy return on energy investment) of an installed panel is 3 years (average, see  and ). And the installed capacity, nationally, doubles every year, then the CO2 emission of one year is not yet compensated, if twice as many panels, will be installed already the next year. And four times as much in the third year. CO2 emissions as a result of renewable energy therefore continue to rise, despite of increased renewable energy production! And that also works exponentially: The 3rd year its 4times as big, the 4th year 8x, the fifth year factor 16 and so on. Cumulative that is (since after 3 years the first year is refunded), 1,3,7, 14 28, 56 times the CO2 etc.
Even if the EROI were to be 2 years, this will remain the effect though a bit slower: accumulated that is 1,3,6 12 24, 48 times.
Only when growth slows down it , production can overtake compensation. For example in a linear way instead of exponential: every year the same amount as before is added to stabilize the CO2, the production of more and more panels can outpace the CO2 emissions of the panels. But with an equal share increase every year, that’s going far too slowly for the energy transition, and we’re never going to get there.
This will only change if: 1) less PV is installed as a year before, 2) the energy mix in the production of panels will be move from fossil to renewable, or 3) if the installed solar panels will really replace fossil: so that every year less fossil is used, as a result of those panels. Then, (in theory) the savings in CO2 could be greater than the investments in CO2 emissions. But that is far from the case, energy consumption is rising and nothing is being contributed by solar panels currently.
This is without even including CO2 emissions of all technologies that are needed in the supportive systems, like conversions and transport. That CO2 adds to the emissions. These technologies can improve the EROI by increasing the efficiency of a system. But they dont produce energy, so ther own embodied CO2 will not be compensated by themselves, except perhaps at system level.
Think of inverters, cables, batteries, networks, but on top of that also of LED lamps, electric cars, the end users. An electric car might drive more effectively, however its production simply costs CO2. And if the production of electric cars grows exponentially , so do their CO2 emissions … And they are not compensated, a car produces no (renewable) energy….
It might make sense if electrical cars actually would lead to lower operational emissions overall, but…: For example: car sales rose last year (2017) by 2.4% 2.05 million more than the previous year.
Of which only 670000 were 100% electric.  All those extra cars therefor caused extra CO2 production. And if the e-car production continues to rise, you get the same effect as with PV panels, then the CO2 emissions will continue to rise despite electric driving.
I have already reported earlier and argued that 1 individual electrical car or 1 0- energy home renovation seems beneficial, and within its limited system boundary it can be, but if you take it cumulatively over the total stock the numbers change. Then, single positive solutions , add up to a negative overall effect.
We should not produce electric cars, for example, but only replace the engine of most existing cars. And continue to drive the same car fro another say 50 years.
Incidentally, for wind turbines the EROI is a lot more favorable, well within a year. The CO2 emissions from production are already recovered, before new turbines are added next year. This then yields net emission returns. In principle, because here too there is another catch: Provided the wind energy replaces fossil energy. Which however usually is not yet the case. Energy use is increasing: Take the example in the North of Netherlands: Eneco, the energy company , built an off-shore wind farm of 19 turbines with electricity for 60000 households, as was announced at the time. Three years later on delivery it turned out that the entire production was sold to Google, for her just completed mega data center in the region. And that center represents only new extra energy demand. The windmills do not contribute any kWh to the sustainability of our current use, only to the extra demand by modern technology ( the consequences of doing things smart….) . In other words, no grams of fossil CO2 emissions have been saved, CO2 emissions have only been added for the construction of that wind farm! (and the data center, of course).
What is not even in the picture is the use of materials for all this new technology, the solar panels, windturbines and related technology., and the consequences of this for our raw material stocks, and indirectly also for energy again: the ore gradients are decreasing, which means that more and more energy is needed for the same amount of recovered metals. And that is going to continue counting … also in more installed Solar Panels for example, it strengthens itself …
In short, the CO2 emissions will continue to rise for a while, partly thanks to the transition to renewable energy. The only thing that really helps today is to drastically reduce the use of energy.
Its just like that.
 Energy payback time (EPBT) and energy return on energy invested (EROI) of solar photovoltaic systems: A systematic review and meta-analysis. Khagendra P. Bhandari et all, 2015