Abstract
Statement
of the Problem: In 2050 it is
expected to reduce CO2 to 80% in all sectors [1]. Some want net-zero [2]. But
if there are no precise paths it seems impossible for most scientists,
economists and politicians. 20% is 2%/year and 0% is 2.7% average. It should go
faster in before 2030 to avoid problems close to 2050. CO2 could be a valuable
resource, to valuable and too risky to dump underground. However a few examples
could give ideas how things could change without big costs. In practice also
some big steps may be easier to implement than a series of small steps. Why
improving a step of 5% when a step of a factor 5 is also possible? An example could be heating of dwellings in
the northern countries: it is even possible in several ways. An example is,
if still natural gas is used and CO2 storage, to use SOFC with bottom cycle
GTCC and vacuum insulation at dwellings, a factor 10 is realistic1.
Another way is to store heat in hot water (= the re-invention of hot water). If
100 m3 of storage is used, it has an equivalent of 8000 kWh of heat2.
If the same is done with hydrogen, it is less easy2.Well insulated
houses do not need so much energy and to make PV or other means still energy is
needed. The major part of that energy can be generated by a full PV roof, so
all directions. Today, PV panels cost in detail 65 €/m^2 taxes and transport
included, and 33 €/m^2 in large scale without taxes and transport [3]. “Full
roof PV” should be preferred or imposed instead of tiles. It is possible to get
roofs tight3, even when using standard panels and even recuperate
the warm air under it. A third way is having a centralized PV farm where
methanol is made with CO2 from air (it will be > 500 ppm at that time, and
even more inside buildings with people). A factory can make methanol from CO2
using renewable electricity [Olah Iceland, geothermal and hydro]. Air
conditioning could work during sun and store in ice. Another
example is the daily person mobility. Today, electric cars need about 15
kWh/100 km, but transport 1500 kg for typically one or two persons, often at an
average speed of 20-45 km/h and a maximum speed of 120 km/h. If an electric
ultralight vehicle of 150 kg is used[4], two persons could be moved behind each
other at max. 90 km/h using 3-4 kWh/100 km, we have the factor 4 from 2020 at
80% to 2050 at 20%. Further on, 4 PV panels of 1.65 m2 could
compensate the electricity needed for 20000 km/year. A third example is airplane mobility. Short distances could use
batteries, most of model airplanes and drones are already electric driven. Long
range could be obtained using by methanol or derived substances from it. In
fact, the cheapest PV electricity is much cheaper than wind or hydro. Some
processes are reported form CO2 and H2 at below 250°C [5]. The efficiency from
PV to methanol and from methanol to could be similar to hydro to methanol. If
CO2 is recuperated for free, and optimized, about 10 kWh of electricity is
needed to produce 1 liter of methanol. Can one still fly 10000 km/year? It
needs 44 m2 of PV roof4 if conversion and airplanes are
optimized*. People think they could do the same with cars, however it would be
wrong to “waste” all PV surface to move the today heavy cars. So airplane
mobility is still possible if the personal vehicle mobility is optimized, and
also space heating/cooling. A fourth question could be, will we have enough
electricity in the middle of the winter? The first idea is to import it from
more sunny countries where mainly electricity is needed in summer for air
conditioning. However, transporting it could be much more expensive than
generating it. The cheapest recent bid was 0.0179 $/kWh in large scale in UAE
[6]. If a good technology from PV to methanol is developed it can be cheaper
than the today production from natural gas. The summer electricity from
oversized panels in Europe could also deliver a part for the winter. Today most
of PV roofs are a “patchwork” of some panels. At the actual price/m2,
the whole roof can be PV: south, east, west and even north. The north roof
plane produces as much as south in cloudy weather, and so equalizes the
production, with is an advantage for the coupled converters and grid. If a DC
technology is used instead of DC/AC, converters will be cheaper. A lot of
appliances can be used during day and store themselves (electric boilers,
laptop, electric vehicles). So using PV at home and at the job to charge. In
the paragraphs before, mainly PV was emphasized, but hydro, wind, tidal,
geothermal can help the renewable energy mix, they will be more expensive than
pure solar, but cheaper than stored solar. It is under discussion but if
biomass heating can be good for the country side, and if optimized at the city
border, for district heating and carbon dioxide reuse.
Not
that the IT sector might remain
with a big relative part. There is some job to do: all household instruments
have energy labels, but why not routers? It is a shame, this should change.
Television sets have a stand-by of 0.1W and WIFI 9W? So one Wi-Fi has a
stand-by of 90 TV sets and takes as much power as and a+++ fridge? It is stated
that “All sectors need to contribute to the low-carbon transition”, so without
exception [1].
Conclusion
At a first sight, 20% CO2 or even
net-zero in 2050 seems an almost impossible task. However, if the best available
technologies of today are combined, it seems more feasible than ever. Not
forgetting that it will take time and effort to develop and implement these
techniques. One should not be happy with small improvements, but rather think
in a technology in large steps that gradually penetrates the society. It is
even possible at an affordable cost, but it might be a slightly different
living style, but where the major part of activities is still possible. The
problem will be to convince the society that “business as usual” and some small
changes are not enough.