Michael Carbajales-Dale

Can we afford storage? A dynamic net energy analysis of renewable electricity generation supported by energy storage

Global wind power and photovoltaic (PV) installed capacities are growing at very high rates (20% per year and 60% per year, respectively). These technologies require large, ‘up-front’ energetic investments. Conceptually, as these industries grow, some proportion of their electrical output is ‘re-invested’ to support manufacture and deployment of new generation capacity. As variable and intermittent, renewable generation capacity increases grid penetration, electrical energy storage will become an ever more important load-balancing technology. These storage technologies are currently expensive and energy intensive to deploy. We explore the impact on net energy production when wind and PV must ‘pay’ the energetic cost of storage deployment. We present the net energy trajectory of these two industries (wind and PV), disaggregated into eight distinct technologies—wind: on-shore and off-shore; PV: single-crystal (sc-), multi-crystalline (mc-), amorphous (a-) and ribbon silicon (Si), cadmium telluride (CdTe), and copper indium gallium (di)selenide (CIGS). The results show that both on-shore and off-shore wind can support the deployment of a very large amount of storage, over 300 hours of geologic storage in the case of on-shore wind. On the other hand, solar PV, which is already energetically expensive compared to wind power, can only ‘afford’ about 24 hours of storage before the industry operates at an energy deficit. The analysis highlights the societal benefits of electricity generation–storage combinations with low energetic costs.

Energy Return on Investment (EROI) of Solar PV: An Attempt at Reconciliation [Point of View]

Examines the importance of energy return on investment (EROI) as a useful metric for assessing long-term viability of energy-dependent systems. Here, focuses on the methods, applications, and analyses for determining EROI for solar power and solar energy technologies.

Disease risk & landscape attributes of tick-borne Borrelia pathogens in the San Francisco Bay Area, California

Habitat heterogeneity influences pathogen ecology by affecting vector abundance and the reservoir host communities. We investigated spatial patterns of disease risk for two human pathogens in the Borrelia genus–B. burgdorferi and B. miyamotoi–that are transmitted by the western black-legged tick, Ixodes pacificus. We collected ticks (349 nymphs, 273 adults) at 20 sites in the San Francisco Bay Area, California, USA. Tick abundance, pathogen prevalence and density of infected nymphs varied widely across sites and habitat type, though nymphal western black-legged ticks were more frequently found, and were more abundant in coast live oak forest and desert/semi-desert scrub (dominated by California sagebrush) habitats. We observed Borrelia infections in ticks at all sites where we able to collect >10 ticks. The recently recognized human pathogen, B. miyamotoi, was observed at a higher prevalence (13/349 nymphs = 3.7%, 95% CI = 2.0–6.3; 5/273 adults = 1.8%, 95% CI = 0.6–4.2) than recent studies from nearby locations (Alameda County, east of the San Francisco Bay), demonstrating that tick-borne disease risk and ecology can vary substantially at small geographic scales, with consequences for public health and disease diagnosis.

Food–energy–water metrics across scales: project to system level

Although much theoretical work has been put into stressing the importance of understanding the food–energy–water nexus, if this burgeoning focus of inquiry is to have any impact on development pathways, we must advance metrics to guide policy planning and action. In this paper, we outline a framework for establishing such a suite of indicators based on system science and life cycle assessment. We identify a number of considerations that should be addressed including the following: (a) scope, ranging from project level (for example, a thermoelectric power plant) through higher system network levels (industry to national to global-level analysis), and (b) the category of the metric, which is defined by two dimensions, (i) intrinsic vs. extrinsic and (ii) absolute vs. relative units, whether the metric indicates an absolute value (for example m3 of freshwater consumption or kWh of electricity used by a power plant) or a value relative to an industry/policy performance benchmark or some environmental indicator (e.g., available water within the basin in which our power plant is located). By understanding the scope and category of metrics derived from economic, life cycle, or other modeling and accounting methods, we understand how various stakeholders are motivated to focus on certain metrics over others. This understanding in turn creates the means to translate between metrics and models for food–energy–water planning and stakeholder collaboration. It should be noted that the primary objective of this paper is to spur discussion, rather than to flesh out a fully formed theoretical framework. We hope, however, that our efforts may prove to be of some use in the crucial discussion of food–energy–water nexus issues.

Assessing the photovoltaic technology landscape: efficiency and energy return on investment (EROI)

This study builds on previous meta-analyses of photovoltaic (PV) systems to assess the tradeoff between efficiency and energy inputs (i.e. cumulative energy demand, CED) in the energetic performance (as measured by energy return on investment (EROI)) of PV technologies under both high-cost and low-cost balance of system scenarios. This study focuses on three existing technology groups (wafer, thin film, and organic). We find that earlier projections of third-generation (high-efficiency, low-cost), thin-film technologies have not yet emerged, since “third-generation” technologies currently have low-cost but also low-efficiency. However, we also find that the best advances in energetic performance to date come from thin film technology.

Life Cycle Assessment: Meta-analysis of Cumulative Energy Demand for Wind Energy Technologies

Abstract Global installed capacity of renewable energy technologies and especially wind energy is growing rapidly. The ability of these technologies to enable a rapid transition to a low-carbon energy system is highly dependent on the energy that must be used over their life cycle; materials extraction and processing, component manufacture and installation, operation, and end-of-life. This chapter presents the results of a meta-analyses of life-cycle assessments (LCA) of energy use by wind turbines. The chapter presents these findings as energetic analogies with financial cost parameters for assessing energy technologies.

Introduction: The End of an Era

We are entering a new era in which biophysical limits related to natural resource extraction rates and the biospheres waste assimilation capacity are becoming binding constraints on mature economies. Unfortunately, the data needed for policy-makers to understand and manage economic growth in the new era are not universally available. In this chapter, we discuss the problems that arise from relying solely on the Solow growth model to describe an economy that is, in reality, deeply interconnected with the biosphere. We point out that mainstream economists forecast low growth rates for mature economies for the foreseeable future, because traditional drivers of economic growth (growth rates of capital and labor productivity) have plateaued. Unfortunately, mainstream policy recommendations to reinvigorate growth, based on the Solow growth model, ignore three critical realities: the economy is tightly coupled to the biosphere, there exist real and binding physical and technological limits to the rate at which materials and energy can be extracted from the biosphere, and today’s emplacement of manufactured capital locks in tomorrow’s material and energy demands from the biosphere. As such, mainstream policy recommendations are likely to fail in the long run: today’s expansion of the stock of capital in the economy in the hopes of enhancing consumption can contribute to the slowdown of economic growth by bringing us ever-closer to biophysical limits. The chapter ends by noting that we need a new way to understand our economy, and we suggest that detailed information about materials, energy, embodied energy, and energy intensity be routinely gathered and analyzed and disseminated from a centralized location to provide markets and policymakers with more-complete knowledge of the biophysical economy.

Stocks and Flows of Economic Value

To quantify financial activities and interdependencies within an economy, economists account for flows of economic value among sectors of the economy. In this chapter, we utilize the prevailing subjective theory of value to develop a framework for value accounting that is consistent with the materials, energy, and embodied energy accounting frameworks presented in prior chapters. We note that important and essential material exchanges between the economy and the biosphere (including energy extraction from the biosphere and waste assimilation by the biosphere) take place outside of the market, and, as such, they are not included in national accounts and have no economic value. We point to the UN System of Environmental Economic Accounts (SEEA) or the US Integrated Environmental Economic Satellite Accounts (IEESA) as the way forward to including some of these essential extra-market transactions in national accounting. Similar to previous chapters, a series of increasingly-disaggregated model economies is used to develop our value accounting framework. Value flows for the US auto industry are presented, and concerns are raised about recent changes to include intangible assets, such as software and intellectual property, as capital stock.

Accounting for the Wealth of Nations

Mainstream economic models, which typically exclude physical transactions between the economy and the biosphere, are incomplete: wastes, pollution, natural resource extraction, and use of ecosystem services are not included. When economic policy is informed by these incomplete models, unexpected negative outcomes can arise. In this chapter, we suggest that the reason for the incompleteness of mainstream economic models is that we incorrectly understand the economy through the outdated metaphor of the economy as a machine. We describe three eras of thinking about the economy, its relationship to the biosphere, and the metaphors that emerged during each era. We argue that as the world enters the age of resource depletion, it is time for a new metaphor: the economy is society’s \emph{metabolism}. We describe the metabolic processes of anabolism, catabolism, and autophagy and draw analogies to key economic processes: capital formation, energy production, and recycling. Based on the machine metaphor, today’s economic policies are unable to address important issues such as appropriate levels and types of capital formation, efficient energy production, wise use of recycling, and the appropriate scale of the economy relative to the biosphere. The problem is compounded by today’s national accounting, which fails to count many beneficial activities in GDP, simply because because GDP measures only what is produced. Thus, wise and beneficial long-term decisions that would that preserve or enhance natural capital (such as refraining from clearcutting forests) might, ultimately, reduce GDP. We conclude that navigating through the age of resource depletion will require expanded national accounting that captures robust, annual data on the entire portfolio of a nation’s wealth (manufactured and natural capital) in addition to data on national income (GDP). The chapter ends with a description of the structure of the rest of the book.

Stocks and Flows of Embodied Energy

In addition to materials and direct energy, accounting for embodied energy is essential to understand how the biophysical economy operates, because it provides an indication of the distribution of intra-economy energy demand created by consumption of goods and services. Furthermore, the energy embodied in manufactured capital provides, to first approximation, an estimate of the energy required to replace depreciated capital. This chapter begins by developing, for the first time in the literature, a rigorous, thermodynamically-based definition of embodied energy. We then show that energy embodied in the products of an economic sector is the sum of all direct energy consumed along the supply chain, including all upstream processing stages. We note that waste heat from a sector is additive to the energy embodied within products of a sector, thereby providing the mechanism for accumulating embodied energy along the manufacturing supply chain. Equations that describe the accumulation and flow of embodied energy through economies are developed through a series of increasingly-disaggregated model economies. Finally, we discuss embodied energy in the context of our running example, the US auto industry. We find that there are very few estimates in the literature of energy embodied within automobiles.