POWER October 2020 - 36

POWER-TO-X
A High Energy Potential:
Power-to-Heat
Though a lesser discussed power-to-x solution, power-to-heat technologies are
already mature, commercially available, and market competitive. And they are
already making an impact on the power sector.
Sonal Patel
M
uch discussion over the past
year has been centered on
power-to-gas (PTG), and particularly,
on power-to-hydrogen, or powerto-methane.
While these technologies'
potential to make a major dent in power
transitions remain laudable, their widespread
uptake isn't projected for a decade
or more.
A specific " power-to-x " prospect that
industry observers point to that could
yield more immediate decarbonization
benefits is " power-to-heat. " Often embedded
within a larger conversation about
electrification of buildings and space
heating, power-to-heat (sometimes abbreviated
as P2H or PTH) simply defines
a process whereby generated power is
used for heating and cooling applications,
typically through heat pumps or boilers.
The emphasis on P2H of late, however,
typically also integrates the use of renewable
power, smart load management, and
thermal storage systems, and the term is
being increasingly used to describe a flexible
coupling of power and heat sectors.
The reason for this, as the International
Energy Agency (IEA) explains, is
that heat accounted for half of global final
energy consumption in 2019, but only
10% was produced using " modern renewable
energy " (which excludes traditional
uses of biomass). According to the
International Renewable Energy Agency
(IRENA), in the U.S., more than 60% of
annual heating and cooling requirements
were met by fossil fuel-based sources,
such as natural gas, propane, and fuel
oil in 2018, and in Europe, about 75% of
annual heating and cooling requirements
were met by fossil fuels in 2019, while
only 19% was generated from renewable
energy. While some heating and
virtually all cooling is electric, renewable
P2H refers to the use of renewable power
to generate economically justifiable
demand for heating or cooling for buildings
or industrial processes.
This, it notes, is typically accomplished
36
with electric boilers, which use power
to heat water, which is then circulated
through pipes or disseminated with fan
coils to provide space heating, or stored in
hot water tanks for later use. Heat pumps,
on the other hand, rely on a 160-year-old
concept that uses electricity " to transfer
heat from the surrounding heat sources
(air, water, ground) to buildings. "
The Allure of Heat Pumps
Because heat pumps can fulfill both
heating and cooling requirements-
typically, by using about 66% to 80%
of energy in the ambient air, water, or
ground, and a smaller 20% to 33% from
electricity to drive the process-they
are widely seen as playing a critical role
in the electrification of buildings and
industry sectors. The European Technology
and Innovation Platform on Renewable
Heating and Cooling (RHC), for
example, envisions 100% renewable-
based heating and cooling is possible
on the continent by 2050 if a strong
integration with the power sector is established
using heat pumps and thermal
energy storage, along with the wide uptake
of smart energy systems.
According to the IEA, increased uptake
of heat pumps is already underway.
In 2019, nearly 20 million households
purchased heat pumps, up from 14 million
in 2010, though most of this growth
was from higher sales of reversible units
that can also provide air conditioning,
which reflects rising cooling demand. In
Europe, heat pump sales increased 25%
over the past two years, with high numbers
of air-source heat pumps sold but
steeper growth in heat pump water heaters.
Market research firms are also notably
bullish on an expanding heat pump
market. Allied Market Research, for example,
predicts the global heat pump
market size, which was valued at $55.2
billion in 2018, will nearly double to $99.6
billion by 2026.
The allure of heat pumps as a critical
P2H component lies in its high efficienwww.powermag.com
cies,
notes the RHC. " One unit of electricity
can provide between three and
five units of heat (in very specific designs
even six to seven units are possible). At
the same time, such a system provides
an additional two to four units of cooling,
making overall [heating and cooling] efficiencies
of between five to eight possible, "
it explains. " In more practical terms,
exchanging a fossil boiler with a HP [heat
pump] saves about 50% of primary energy,
while exchanging a direct electric
heating system with a HP frees 2/3 to
3/4 of final/primary energy used. "
Despite their obvious energy efficiency
benefits, meanwhile, the IEA suggests
wider uptake of heat pumps could necessitate
a massive ramp up of power generation,
adding a new burden to some
already heaving, aging grids around the
world. " For example, if heating in all buildings
in Europe was switched to electricity
using heat pumps, peak winter electricity
demand would increase by more than
60%, " it projected under its highly optimistic
2018 " Future is Electric " scenario.
Power-to-Heat Already Reshaping the
Power Sector
Still, as so many case studies of late have
shown, P2H is starting to show tangible
benefits for energy transition strategies.
IRENA notes this is happening on two
broad scales (Figure 1). One is through
centralized heating systems, such as " district
heating or cooling networks, " where
large-scale electric boilers and heat
pumps are supplied with power directly
from the main grid, or via combined heat
and power plants. The other case is in decentralized
heating systems, such as in industry,
which use small-scale heat pumps
or electric boilers for heating or cooling
that are powered by the grid, or directly,
such as with rooftop solar, behind-the-meter
batteries, and other storage system.
Moderating Renewable Energy Curtailment.
As renewables ramp up boosted
by incentives and market value, P2H
is starting to provide a new mechanism
POWER | October 2020
http://www.powermag.com
POWER October 2020

Table of Contents for the Digital Edition of POWER October 2020
