Comparison of lithium-ion battery, lead-acid battery and hydrogen storage for enduser/utility applications: a community optimum approach
David Parra
Prof. Mark Gillott and Prof. Gavin S. Walker
Faculty of Engineering, Energy and Sustainability Division
Background
•
•
•
•
•
UK CO2 emissions must be reduced by 28 % by 2020 (taking 1990 as a reference )[1].
Renewable energy technologies are necessary to achieve this target, but their generation is variable and
mismatches the domestic demand load.
The decarbonisation of the heating sector (Table 1) by using heat pumps and CHP units will modify current
demand profiles and peak demand will increase.
The demand and generation profiles will change at consumption level therefore keeping the system balance
is a key objective.
Is energy storage necessary to achieve these decarbonisation targets? What is the optimum size
of energy storage?
Figure 1: Daily and seasonal mismatch in a single house
Methodology for Evaluating Energy Storage Applications and Financial Benefits for End-user Utility Applications
Applications
Valley time?
no
• Renewable energy
time-shift
• Heat decarbonisation
• Load-shifting
yes
Efficiency >
(valley/peak)
price
SOC>
SOC (min)
no
yes
no
Discharge
no
• Battery
• Water tank
• Hydrogen
no
Assess financial
benefit
Figure 2: Load shifting flow chart
• The size of the
community is varied
to test energy storage
performance
yes
SOC >
SOC (max)
SOC >
SOC (min)
Community approach
• Technology cost and
life
• Tariffs
• Incentives
yes
Charge <
Forecast
Load
Generation
> Load
SOC <
SOC (max)
yes
Load shifting
Generation
yes
Import from
the grid
yes
Suitable
technologies
yes
no
Import
Figure 3: Community approach for obtaining the optimum size
Discharge
yes
no
Charge
Export
Figure 4: PV energy time-shift flow chart
Modelling scenarios: 2010, 2020 and 2050
Year
Electricity
demand
(MWh/year)
Space Heating
demand
(MWh/year)
Domestic hot
water
demand
(MWh/year)
PV energy
penetration
(%)1
Low carbon heat
generators
penetration (%)1
Tariffs2
Energy storage
cost3
Energy
storage life3
2010
11.5
3.9
3.3
1.3
0
Economy 7
Current
technology cost
Current
technology
life
2020
9.4-10.0
3.3
3.3
2.4-7.3
14.2
2050
7.2-8.3
2.4-2.9
3.0-3.3
50.6-56.0
100
4 period
tariff
Target cost
Target life
1: Percentage of houses with a PV array (3 kWp) ;
heat pump, CHP unit or biomass boiler.
2: The electricity tariff in 2020 and 2050 is based on
the prices from the Imbalance market (2011) when
increasing the volatility.
3: The cost and durability of different energy storage
technologies is based on current data (2010) and
future projections (2020 and 2050)
Table 1: Changes in the energy demand and generation according to [2] where the most plausible pathways for achieving 2050’s objectives are defined.
Results: Optimum Community Energy Storage Modelling
2020
2010
a
b
a
Figures 6: a) Prices from the New Electricity Market Agreement (NETA) in
the UK along a day for every day of the year in 2011; b) Lead-acid and
lithium-ion battery efficiency and discharge for a 25 house community when
performing load shifting with a four period tariff derived from NETA prices.
Figures 5: a) Lead-acid and lithium-ion battery efficiency and discharge for a single house when
performing PV energy time-shift or load shifting; b) Lead-acid and lithium-ion battery efficiency and
discharge for a 25 house community when performing load shifting; c) Lead-acid and lithium-ion
battery life when performing load shifting for a 25 house community.
Conclusions
2050
b
a
c
Figures 7: a) Lead-acid and lithium-ion battery efficiency and discharge for a 100 house community
when performing PV energy time-shift considering the heat demand by heat pumps; b) CHP hydrogen
mass consumption and electrolyser hydrogen generation when considering PEM technology as a
function of the size of the community c) CHP hydrogen mass consumption and electrolyser hydrogen
generation when considering PEM technology for a 60 house community.
References
b
c
[1] Low Carbon Transition Plan. Department of Energy and Climate Change .
[2] 2050 Pathways Analysis. Department of energy and Climate Change
• The power rate of the inverter can reduce the impact of a
lithium-ion battery for end-user applications.
• Heat demand increases the energy flow and reduces the life of
lead-acid battery technology.
• As the price of electricity becomes more volatile, the discharge
due to load shifting decreases but the revenue may increase.
• An electrolyser on-site performing PV energy time-shift is able
to supply around 20 % of the CHP hydrogen needs.
• Hydrogen seasonal storage is only feasible in a scenario with
no heat requirements over the summer in 2050 when
performing PV energy time-shift.
• Mid-term seasonal storage could be achieved when performing
PV energy time-shift and load-shifting.
• The combinations of applications will be investigated to
increase the value of energy storage.