by Dan Layug, CFA and Army Major Nicholas Ng
The climate impact of US Army installations
The US Army is the US government’s largest emitter of Greenhouse Gasses (“GHG”). In 2020, the Army purchased over $740M of electricity from electric grids. This electricity added 4.1 million metric tons of carbon dioxide as well as methane, nitrous oxide, and other GHGs into the atmosphere.[i] This indicates that the grids they source from have an average carbon intensity estimated at 0.5868 tons of CO2e per MWh. This is ~35% more emissions per energy unit of energy than the US grid as a whole.[ii]
Climate strategy of the US Army
In recent years, the military branch has increased its efforts to address its carbon footprint. Earlier this year, the Army released the United States Army Climate Strategy which contains the following goals or end state:
- Achieve 50% reduction in Army net GHG pollution by 2030, compared to 2005 levels;
- Attain net-zero Army GHG emissions by 2050; and
- Proactively consider the security implications of climate change in strategy, planning, acquisition, supply chain, and programming documents and processes.
The Army plans to achieve its ambitious strategy through three lines of effort which include 1) Installations, 2) Acquisition & 3) Logistics and Training. Each line of effort has a strategic outcome followed by a set of intermediate objectives.
For the Installations line of effort (LOE1), the strategy contains several ambitious objectives, including:
- Installing a microgrid within every base by 2035;
- Fielding an all-electric light-duty non-tactical vehicle fleet by 2027; and
- Providing 100% carbon-pollution-free electricity for Army installations’ needs by 2030.[iii]
To achieve this strategy, the Army will need to overcome challenges in energy storage, procurement, and sustainability of the new electric vehicles (EVs). For more information, find the full US Army Climate Strategy in this link.
The typical military installation
According to the US Army’s climate strategy, there are over 130 Army installations around the world.[iv] Army bases vary greatly by size –from as small as a few buildings within a compound to large installations of over 200,000 people, of which a fraction are uniformed personnel. Many of the middle to large-sized bases have similar types of electricity load profiles. This includes:
- A commercial and industrial customer base (C&I) of office buildings, labs and workshops;
- A Network Enterprise Center (NECs) which functions as the data center of the installation;
- Services like commissaries, exchanges, gas stations, and training facilities; and
- Residential housing for on-base personnel.
According a Noblis report, the average military base has a load profile that peaks at 50MW and has a critical load of 20MW. This report indicated that stationary energy storage with a duration of at least 16 hours would be required for a military microgrid to be fully reliant on on-site variable renewable energy (“VRE”).[v]
With such diverse electricity usage on military installations, the Army could take into consideration a few trends as it implements its climate strategy.
Recent trends: VRE + Storage costs dropping over the past 10yrs
Variable renewables and storage projects have increased rapidly in the past decade, mainly due to decreasing capex costs required for photovoltaic (PV) systems. Solar and onshore wind capex costs have decreased 80% and 45%, respectively, over the past 10 years and are expected to drop further in the next 10 years.[vi] The Levelized Cost of Storage (“LCOS”) of lithium-ion technology has also dropped ~82.9% per MWh in the same period.[vii]
Li-ion Battery Energy Storage System (“BESS”) capex are expected to increase in the short term due to the sector competing for li-ion supply with the electric vehicle industry, which provides battery manufacturers larger order quantities and better margins.
Fortunately, the improving economics of Long Duration Energy Storage (“LDES”) systems with durations of ~16 hours are expected to pick up the demand for stationary energy storage. Furthermore, flow battery (an LDES technology) costs are expected to decrease by 10%-11% annually.[viii]
Adding to the attractiveness of green minigrids, fossil fuel costs have increased drastically in 2022 with little signs of relief. This includes prices for natural gas, coal, diesel, and gasoline. Because of this, the price of electricity sourced from the US grid has also increased since ~80% of the energy mix is made up of fossil fuel-based energy generation.[ix] With the backdrop of stabilizing defense spending due to the reduction of contingency overseas operations, this creates urgency for the Army to meet its Net Zero objectives while providing power reliability and energy security for the force.
Recommendations: Meeting the US Army’s Intermediate Climate Objectives for Installations
- Baseload renewable minigrid
A low carbon solution is a minigrid made up of grid-connected Solar PV or Wind generation coupled with flow BESS. The hybrid system would be able to provide dispatchable energy for all the electricity requirements of a military base. This minigrid, with generation distributed around the base, could be connected to the existing distribution system for buildings and the fuel stations for electric vehicles. Existing diesel back-up gensets can be kept in place for redundancy, but used only in extreme events.
Electricity sourced exclusively from the main grid emits 53k tons of CO2e annually per base and costs ~$0.10 per kWh. An all-diesel minigrid would emit 79k tons of CO2e annually per base at a significant premium depending on the price of diesel fuel. On an apples-to-apples comparison, a green minigrid would “emit” only 6% of the CO2e (primarily from manufacturing of the solar+storage system) at a small incremental premium when compared with sourcing exclusively from the main grid.
Given the favorable economics and emissions levels, solar+storage minigrids should be the recommended choice for the Army to simultaneously meet LOE1 — Objective 1.1 (Installing a microgrid in every installation by 2035), LOE1 — Objective 1.2 (Achieve on-site carbon pollution-free power generation for Army critical missions on all installations by 2040), and LOE1 — Objective 1.3 (Provide 100% carbon-pollution-free electricity by 2030). See previous article on baseload renewables around the world for more information.
2. Low-carbon buildings within installations
Decarbonizing buildings and vehicles requires an electricity grid powered by renewables, which is not sustainable without energy storage. An energy storage system would enable cost-effective deep decarbonization of minigrid systems that rely heavily on variable renewables, without sacrificing system reliability. In addition to allowing for variable energy usage throughout the day, the flow battery also has fast-response capability to react to daily/weekly variability and regulate frequency and voltage. This system set-up also gives the base the flexibility to switch between grid-mode and island mode depending on the cost at any given time.
Existing buildings can reduce their climate impact by investing in activities and utilizing rooftops for solar PV. New-build construction can also take advantage of low-carbon concrete. The Network Enterprise Centers (NECs), like a private data center, at large bases need to run 24x7. These buildings offer a strong opportunity to lower base-wide carbon footprint. A 20MW NEC with rooftop solar could offset 24k tons of CO2e over a 25yr life. Using low-carbon concrete instead of regular concrete could reduce construction-related emissions by 960k tons of CO2e.
Clean energy procurement is the best option to lower carbon footprint on an overall level for a military base.
For an installation with critical load of 20MW, sourcing energy from a solar PV + flow battery minigrid could offset 2.6m tons of CO2e per Army installation over a 25yr life. Furthermore, the returns for the above three activities would be net present value positive (NPV+) investments for the Army.
Additionally, most investments in energy efficiency also offer a vast, low-cost, high-return solution. Energy efficiency has a negative abatement cost which means these low-carbon options are lower cost than business-as-usual options per kg of CO2 emitted. Efficiency is an important resource that can help reduce GHG emissions while the Army builds up clean energy supply.
These activities would allow the Army to achieve LOE1 — Objective 1.5 (Achieve 50% reduction in GHG emissions from all Army buildings by 2032).
3. Retrofitting traditional gas stations with stationary ESS
In addition to electric vehicle (EV) adoption by military families, the Army’s goal is to field an all-electric light-duty non-tactical vehicle fleet by 2027. Due to EV adoption, on-base gas stations may soon face lower demand for petroleum products. This could result in multiple unutilized underground storage tanks. These make gas stations ideal locations to meet the charging requirements of the personally-owned and the Army-owned EV fleet.
As flow battery systems are modular, smaller versions of the ESS can be utilized. Redox flow batteries allow for the flexibility to install both slow chargers and fast chargers. To complete the retrofit, one need only renovate an empty underground tank at gas stations to store electrolyte instead of gasoline/diesel. This would enable Army installations to meet LOE1 — Objective 1.7 (Field an all-electric light-duty non-tactical vehicle fleet by 2027).
Additionally, e-buses can be utilized as circulators around the bases or as transport vehicles bringing soldiers to training sites. See previous article on the total cost of ownership of e-buses vs diesel buses.
For the remaining emissions (Scope 2 and Scope 3), the Army could purchase Carbon Emissions Reductions to be able to attain LOE1 — Objective 1.6 (Net-zero GHG emissions from Army Installations by 2045).
Establishing the Army’s Climate Strategy is definitely a large first step to reaching the Department of Defense and US Government targets for carbon emissions reductions. Execution of the strategy will be a true test of the Army’s ability to overcome a decades-old dependency on fossil fuels and the local grid where installations are located. The recommendations highlighted above present several ways to leverage the latest renewable energy technologies to achieve the intermediate outcomes for LOE1 — Installations. In the long run, it will take a concerted effort by everyone involved including policy guidance from the Pentagon, sustainably conscious acquisition decisions at each echelon and a culture change within the Army commanders and formations to successfully reach net-zero.
[i] Department of the Army, Office of the Assistant Secretary of the Army for Installations, Energy and Environment (February 2022). “US Army Climate Strategy.” https://www.army.mil/e2/downloads/rv7/about/2022_army_climate_strategy.pdf
[ii] US Energy Information Agency. “Frequently Asked Questions.” https://www.eia.gov/tools/faqs/faq.php?id=74&t=11#:~:text=In%202020%2C%20total%20U.S.%20electricity,CO2%20emissions%20per%20kWh.
[iii] Department of the Army, Office of the Assistant Secretary of the Army for Installations, Energy and Environment (February 2022). “US Army Climate Strategy.” https://www.army.mil/e2/downloads/rv7/about/2022_army_climate_strategy.pdf
[iv] Department of the Army, Office of the Assistant Secretary of the Army for Installations, Energy and Environment (February 2022). “US Army Climate Strategy.” https://www.army.mil/e2/downloads/rv7/about/2022_army_climate_strategy.pdf
[v] Noblis (January 2017). “Power Begins at Home: Assured Energy for U.S. Military Bases.” https://www.pewtrusts.org/~/media/assets/2017/01/ce_power_begins_at_home_assured_energy_for_us_military_bases.pdf
[vii] BloombergNEF energy storage database
[viii] LDES Council and McKinsey (May 2022). “A path towards full grid decarbonization with 24/7 clean Power Purchase Agreements.” https://www.mckinsey.com/industries/electric-power-and-natural-gas/our-insights/decarbonizing-the-grid-with-24-7-clean-power-purchase-agreements
[ix] US Energy Information Agency. “US Energy Facts Explained.” https://www.eia.gov/energyexplained/us-energy-facts/
Disclaimer: This post reflects personal views of the authors and not those of the US Military, the US Army, any other member of the US Armed Forces, International Finance Corporation, World Bank, or any other member of the World Bank Group