How much land is needed to run the world on solar power? (Solar Energy Course 2020 Part 4 of 12)

How much land is needed to run the world on solar power? (Solar Energy Course 2020 Part 4 of 12)


How much land would we need to run the world
on solar power? We’ll answer this question using
– a back-of-the-envelope calculation – the results of a study carried out by a
renewable energy organization – and an estimate by the US Department of
Energy for a solar-powered USA. This video is part of iPolytek’s online course
on solar energy. iPolytek, Professional Development Courses
for Engineers. The Earth receives 174 petawatts (PW) from
the sun in the upper atmosphere. This equates to 340 W/m2.
– 29 % is reflected back to space – 48 % reaches the surface of the planet
– The remaining 23% are absorbed in the atmosphere. The solar energy available for electricity
production at the Earth’s surface varies across the planet. It is affected by factors such as :
– latitude, – season,
– cloud cover – atmospheric conditions (dust,
water vapour, etc) The figure above shows the amount of terrestrial
irradiance falling on a surface that is horizontal to the surface of the Earth. This is known
as the Global Horizontal Irradiance (GHI). This type of energy could potentially be captured
by PV technology. GHI maps allow you to determine the daily
and annual average amount of solar energy falling in your location in terms of kWh/m2. It is hard to imagine how big this amount
of energy is. To help us understand it, let’s use the world’s
Total Primary Energy Supply (TPES) as a point of reference. Primary Energy is the energy embodied in natural
resources (e.g., coal, crude oil, natural gas, uranium) before
being modified in any way by humans. The TPES is the total combined energy available
from all resources worldwide: – coal,
– oil, – natural gas,
– biofuels, – nuclear and,
– hydropower. Let’s take the TPES of 2014 as an example. The Total primary energy supply in that year
was 13 700 Mtoe or 159 Peta Watt-hour. – 31% of that energy was supplied by oil
– 29% by coal – 21% by natural gas
– 10% by biofuels – 5% by nuclear
– 2% by hydro and – 2% by other sources We will see that the global TPES is only a
fraction of the energy we receive from the sun on an annual basis. If the global TPES were to be supplied entirely
from sunlight, a certain amount of land would be needed for the solar modules. The size of that area would largely depend
on the efficiency of the solar cells used. If we assume a conservative photovoltaic efficiency
of 8 %, we can show that six locations in the world, working together, would be capable
of supplying the world’s TPES of 159 PWh from the sun. The names of these deserts, their sizes, their
annual global horizontal irradiation and the land areas required for these theoretical
PV installations are listed in the Table below. This rough calculation shows that the 159
PWh of energy can be collected in these deserts without exceeding
their land areas. This map shows roughly where these deserts
are located. This theoretical calculation gives us an appreciation
for the amount of solar energy that is available for the production of electricity. It shows that, in theory, the global TPES
could be replaced entirely with solar energy using only six unpopulated locations in the
world. This type of calculation has been done by
numerous organisations with the same result. There is enough energy in sunlight to power
the world using today’s solar panels. Land Art Generator, an organization whose
goal is to promote renewable energy, did this calculation by:
– Assuming a solar panel efficiency of 20% (like today’s solar modules)
– Accounting for local electricity consumption and solar irradiation. They concluded that:
– an area roughly equivalent to the size of Spain would be sufficient to supply the world’s energy needs. The total area that would be required in 2030
(represented by a large square in the legend above) is distributed on the map according
to the energy consumption and solar irradiation found in these different places. The areas shown on the map are determined
by assuming an efficiency of 20% for the solar energy collection devices at solar
irradiation of 2000 hours/year at 1000 Watts/m2. Although, only a few squares are shown on
the map, in practice, their areas would be distributed in many facilities to localize
production. Amazingly, the Saharan desert (which represents
25% of the total area required in 2030) could power all
of Europe and North Africa. The areas shown could collectively supply
all global energy needs including all industrial consumption and all forms of transport. Finally, this calculation is based on statistics
published by the U.S. Department of Energy which predict that the global energy demand in 2030
(678 quadruillion Btu) will exceed that of 2008 by 44%. In 2008 the US Department of Energy published
a report entitled, “Land-use requirements and the per-capita
solar footprint for photovoltaic generation in the United States”. In it, the National Renewable Energy Laboratory
(NREL) set out to estimate the land area required to supply all end-use electricity from solar photovoltaics (PV) in the USA. They concluded that the overall average solar
electric footprint was 181 m2 per person. This ranged from 50 to over 450 m2 per person
depending on the scenario and state being studied. Based on this, they calculated the LAND AREA
REQUIRED TO SUPPLY ALL END-USE ELECTRICITY FROM SOLAR PV in the United States was 0.6% of the country’s total land area. In 2013, the NREL published the follow-up
report “Land-Use Requirements for Solar Power Plants in the United States”. In a news release, the authors stated, “The numbers aren’t good news or bad news.
It’s just that there was not an understanding of actual land-use requirements
before this work. However, we were happy to find out that many
of the solar land use ranges and estimates used in the literature are very
close to actual solar land use requirements that we found.” From this we can conclude that the 0.6% total land area estimated by the previous report to be a pretty close to the truth. We see now that solar power could grow to
become a big part of our energy future. So, let’s learn more about this technology. How does a solar cell produce electricity? Find out in our next video! Thanks for watching and see you soon.

Leave a Reply

Your email address will not be published. Required fields are marked *